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  • 1. Afonso, Damien
    et al.
    Valetti, Sabrina
    Fraix, Aurore
    Bascetta, Claudia
    Petralia, Salvatore
    Conoci, Sabrina
    Feiler, Adam
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Sortino, Salvatore
    Multivalent mesoporous silica nanoparticles photo-delivering nitric oxide with carbon dots as fluorescence reporters2017In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 9, no 36, p. 13404-13408Article in journal (Refereed)
    Abstract [en]

    Amino-terminated mesoporous silica nanoparticles embedding carbon dots (MSCD) formed by calcination were functionalized with a nitric oxide (NO) photodonor (1) to give a robust MSCD-1 conjugate. The intense fluorescence of MSCDs was strongly quenched in MSCD-1 by effective energy transfer. Visible light excitation of MSCD-1 liberates NO, suppresses the energy transfer mechanism and leads to concomitant fluorescence restoration of the MSCD scaffold, which acts as an optical reporter for the released NO. The MSCD-1 hybrid is also able to encapsulate the highly hydrophobic photosensitizer temoporfin, preserving the fluorescence reporting function.

  • 2.
    Banuazizi, Seyed Amir Hossein
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Sani, Sohrab R.
    Eklund, Anders
    KTH, School of Information and Communication Technology (ICT), Electronics, Integrated devices and circuits.
    Naiini, Maziar M.
    KTH, School of Information and Communication Technology (ICT), Electronics, Integrated devices and circuits.
    Mohseni, Seyed Majid
    Chung, Sunjae
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics. Univ Gothenburg, Sweden.
    Durrenfeld, Philipp
    Malm, B. Gunnar
    KTH, School of Information and Communication Technology (ICT), Electronics, Integrated devices and circuits.
    Åkerman, Johan
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics. Univ Gothenburg, Sweden.
    Order of magnitude improvement of nano-contact spin torque nano-oscillator performance2017In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 9, no 5, p. 1896-1900Article in journal (Refereed)
    Abstract [en]

    Spin torque nano-oscillators (STNO) represent a unique class of nano-scale microwave signal generators and offer a combination of intriguing properties, such as nano sized footprint, ultrafast modulation rates, and highly tunable microwave frequencies from 100 MHz to close to 100 GHz. However, their low output power and relatively high threshold current still limit their applicability and must be improved. In this study, we investigate the influence of the bottom Cu electrode thickness (t(Cu)) in nano-contact STNOs based on Co/Cu/NiFe GMR stacks and with nano-contact diameters ranging from 60 to 500 nm. Increasing t(Cu) from 10 to 70 nm results in a 40% reduction of the threshold current, an order of magnitude higher microwave output power, and close to two orders of magnitude better power conversion efficiency. Numerical simulations of the current distribution suggest that these dramatic improvements originate from a strongly reduced lateral current spread in the magneto-dynamically active region.

  • 3.
    Cava, Carlos Eduardo
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Multiscale Materials Modelling.
    Persson, Clas
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Multiscale Materials Modelling.
    Zarbin, Aldo J.G.
    Roman, Lucimara Stolz
    Resistive switching in iron-oxide-filled carbon nanotubes2014In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 6, no 1, p. 378-384Article in journal (Refereed)
    Abstract [en]

    Iron-oxide-filled carbon nanotubes have an intriguing charge bipolarization behaviour which allows the material to be applied in resistive memory devices. Raman analysis conducted with an electric field applied in situ shows the Kohn anomalies and a strong modification of the electronic properties related with the applied voltage intensity. As well as, the ID/IG ratio indicated the reversibility of this process. The electric characterization indicated an electronic transport governed by two main kind of charge hopping, one between the filling and nanotube and other between the nanotube shells.

  • 4.
    Chen, Xi
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Chen, Yiting
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Dai, Jin
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Yan, Min
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Zhao, Ding
    Li, Qiang
    Qiu, Min
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Ordered Au nanocrystals on a substrate formed by light-induced rapid annealing2014In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 6, no 3, p. 1756-1762Article in journal (Refereed)
    Abstract [en]

    Light-induced rapid annealing (LIRA) is a widely used method to modify the morphology and crystallinity of noble metal nanoparticles, and the nanoparticles generally evolve into nanospheres. It is rather challenging to form faceted Au nanocrystals on a substrate using LIRA. Here the formation of spatially ordered Au nanocrystals using a continuous wave infrared laser is reported, assisted by a metamaterial perfect absorber. Faceted Au nanocrystals in truncated-octahedral or multi-twinned geometries can be obtained. The evolution of morphology and crystallinity of the Au nanoparticles during laser annealing is also revealed, where the crystal grain growth and the surface melting are shown to play key roles in nanocrystal formation. The evolution of morphology also gives the freedom of tuning the absorption spectrum of the metamaterial absorber. These findings provide a novel way for tailoring the morphology and crystallinity of metallic nanoparticles and may pave the way to fabricate refined nano-devices in many potential applications for optics, electronics, catalysis, surface-chemistry and biology.

  • 5.
    Chen, Zhi-Hui
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics. Taiyuan University of Technology, China; Beijing University of Posts and Telecommunications, China .
    Wang, Yang
    KTH, School of Biotechnology (BIO), Industrial Biotechnology.
    Yang, Yibiao
    Qiao, Na
    Wang, Yuncai
    Yu, Zhongyuan
    Enhanced normal-direction excitation and emission of dual-emitting quantum dots on a cascaded photonic crystal surface2014In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 6, no 24, p. 14708-14715Article in journal (Refereed)
    Abstract [en]

    Large normal-direction excitation and emission of dual-emitting quantum dots (QDs) are essential for practical application of QD sensors based on the ratiometric fluorescence response. We have numerically demonstrated an all-dielectric four-layer cascaded photonic crystal (CPC) structure (alternating TiO2 and SiO2/SU8 layers with two dimensional nanoscale patterns in each layer) which is capable of providing normal-direction high Q-factor leaky modes at excitation wavelengths of QDs and two low Q-factor leaky modes coinciding with the two emission peaks of a dual-emitting QD. Normal-direction excitation and far-field emission of the dual-emitting QDs are enhanced significantly when QDs are distributed on/in the top TiO2 layer of the CPC structure, especially in the spatial distribution areas of the resonant leaky modes. QDs can be positioned differently depending on the applications. Positioning QDs on the top TiO2 layer will improve the signal-to-noise ratios of QD biomedical/chemical/temperature sensors, while embedding QDs in the top TiO2 layer will increase the light extraction from the QD light emitting device, making our CPC a versatile optical coupling structure. Our CPC-QD structure is experimentally feasible and robust against the parameter perturbation in real fabrication.

  • 6.
    Delekta, Szymon Sollami
    et al.
    KTH, School of Information and Communication Technology (ICT), Electronics, Integrated devices and circuits.
    Smith, Anderson David
    KTH, School of Information and Communication Technology (ICT), Electronics.
    Li, Jiantong
    KTH, School of Information and Communication Technology (ICT), Electronics, Integrated devices and circuits.
    Östling, Mikael
    KTH, School of Information and Communication Technology (ICT), Electronics, Integrated devices and circuits.
    Inkjet printed highly transparent and flexible graphene micro-supercapacitors2017In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 9, no 21, p. 6998-7005Article in journal (Refereed)
    Abstract [en]

    Modern energy storage devices for portable and wearable technologies must fulfill a number of requirements, such as small size, flexibility, thinness, reliability, transparency, manufacturing simplicity and performance, in order to be competitive in an ever expanding market. To this end, a comprehensive inkjet printing process is developed for the scalable and low-cost fabrication of transparent and flexible micro-supercapacitors. These solid-state devices, with printed thin films of graphene flakes as interdigitated electrodes, exhibit excellent performance versus transparency (ranging from a single-electrode areal capacitance of 16 mu F cm(-2) at transmittance of 90% to a capacitance of 99 mu F cm(-2) at transmittance of 71%). Also, transparent and flexible devices are fabricated, showing negligible capacitance degradation during bending. The ease of manufacturing coupled with their great capacitive properties opens up new potential applications for energy storage devices ranging from portable solar cells to wearable sensors.

  • 7.
    Dias, Jorge T.
    et al.
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Lama, Lara
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Gantelius, Jesper
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Andersson-Svahn, Helene
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Minimizing antibody cross-reactivity in multiplex detection of biomarkers in paper-based point-of-care assays2016In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 8, no 15, p. 8195-8201Article in journal (Refereed)
    Abstract [en]

    Highly multiplexed immunoassays could allow convenient screening of hundreds or thousands of protein biomarkers simultaneously in a clinical sample such as serum or plasma, potentially allowing improved diagnostic accuracy and clinical management of many conditions such as autoimmune disorders, infections, and several cancers. Currently, antibody microarray-based tests are limited in part due to cross reactivity from detection antibody reagents. Here we present a strategy that reduces the cross-reactivity between nanoparticle-bound reporter antibodies through the application of ultrasound energy. By this concept, it was possible to achieve a sensitivity 10(3)-fold (5 pg mL(-1)) lower than when no ultrasound was applied (50 ng mL(-1)) for the simultaneous detection of three different antigens. The detection limits and variability achieved with this technique rival those obtained with other types of multiplex sandwich assays.

  • 8. Dürrenfeld, P.
    et al.
    Awad, A. A.
    Houshang, A.
    Dumas, R. K.
    Åkerman, Jonas
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    A 20 nm spin Hall nano-oscillator2017In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 9, no 3, p. 1285-1291Article in journal (Refereed)
    Abstract [en]

    Spin Hall nano-oscillators (SHNOs) are an emerging class of pure spin current driven microwave signal generators. Through the fabrication of 20 nm nano-constrictions in Pt/NiFe bilayers, we demonstrate that SHNOs can be scaled down to truly nanoscopic dimensions, with the added benefit of ultra-low operating currents and improved power conversion efficiency. The lateral confinement leads to a strong shape anisotropy field as well as an additional demagnetizing field whose reduction with increasing auto-oscillation amplitude can yield a positive current tunability contrary to the negative tunability commonly observed for localized excitations in extended magnetic layers. Micromagnetic simulations corroborate the experimental findings and suggest that the active magnetodynamic area resides up to 100 nm outside of the nano-constriction. 

  • 9.
    Engström, Joakim
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology.
    Benselfelt, Tobias
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology.
    Wågberg, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    D'Agosto, Franck
    Université de Lyon, Univ Lyon 1, CPE Lyon, CNRS UMR 5265, C2P2 (Chemistry, Catalysis, Polymers & Processes), LCPP, 69616 Villeurbanne, France .
    Lansalot, Muriel
    Université de Lyon, Univ Lyon 1, CPE Lyon, CNRS UMR 5265, C2P2 (Chemistry, Catalysis, Polymers & Processes), LCPP, 69616 Villeurbanne, France .
    Carlmark, Anna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology. RISE.
    Malmström, Eva
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology.
    Tailoring adhesion of anionic surfaces using cationic PISA-latexes – towards tough nanocellulose materials in the wet state2019In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372Article in journal (Refereed)
    Abstract [en]

    Cationic latexes with Tgs ranging between −40 °C and 120 °C were synthesised using n-butyl acrylate (BA) and/or methyl methacrylate (MMA) as the core polymers. Reversible addition–fragmentation chain transfer (RAFT) combined with polymerisation-induced self-assembly (PISA) allowed for in situ chain-extension of a cationic macromolecular RAFT agent (macroRAFT) of poly(N-[3-(dimethylamino)propyl] methacrylamide) (PDMAPMA), used as stabiliser in so-called surfactant-free emulsion polymerisation. The resulting narrowly distributed nanosized latexes adsorbed readily onto silica surfaces and to model surfaces of cellulose nanofibrils, as demonstrated by quartz crystal microbalance with dissipation monitoring (QCM-D) measurements. Adsorption to anionic surfaces increased when increasing ionic strength to 10 mM, indicating the influence of the polyelectrolyte effect exerted by the corona. The polyelectrolyte corona affected the interactions in the wet state, the stability of the latex and re-dispersibility after drying. The QCM-D measurements showed that a lower Tg of the core results in a more strongly interacting adsorbed layer at the solid–liquid interface, despite a comparable adsorbed mass, indicating structural differences of the investigated latexes in the wet state. The two latexes with Tg below room temperature (i.e. PBATg-40 and P(BA-co-MMA)Tg3) exhibited film formation in the wet state, as shown by AFM colloidal probe measurements. It was observed that P(BA-co-MMA)Tg3 latex resulted in the largest pull-off force, above 200 m Nm−1 after 120 s in contact. The strongest wet adhesion was achieved with PDMAPMA-stabilized latexes soft enough to allow for interparticle diffusion of polymer chains, and stiff enough to create a strong adhesive joint. Fundamental understanding of interfacial properties of latexes and cellulose enables controlled and predictive strategies to produce strong and tough materials with high nanocellulose content, both in the wet and dry state.

  • 10. Gan, Zhixing
    et al.
    Xu, Hao
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Hao, Yanling
    Mechanism for excitation-dependent photoluminescence from graphene quantum dots and other graphene oxide derivates: consensus, debates and challenges2016In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 8, no 15, p. 7794-7807Article, review/survey (Refereed)
    Abstract [en]

    Luminescent nanomaterials, with wide applications in biosensing, bioimaging, illumination and display techniques, have been consistently garnering enormous research attention. In particular, those with wavelength-controllable emissions could be highly beneficial. Carbon nanostructures, including graphene quantum dots (GQDs) and other graphene oxide derivates (GODs), with excitation-dependent photoluminescence (PL), which means their fluorescence color could be tuned simply by changing the excitation wavelength, have attracted lots of interest. However the intrinsic mechanism for the excitation-dependent PL is still obscure and fiercely debated presently. In this review, we attempt to summarize the latest efforts to explore the mechanism, including the quantum confinement effect, surface traps model, giant red-edge effect, edge states model and electronegativity of heteroatom model, as well as the newly developed synergistic model, to seek some clues to unravel the mechanism. Meanwhile the controversial difficulties for each model are further discussed. Besides this, the challenges and potential influences of the synthetic methodology and development of the materials are illustrated extensively to elicit more thought and constructive attempts toward their application.

  • 11.
    Ghanadpour, Maryam
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Wicklein, Bernd
    Carosio, Federico
    Wågberg, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    All-natural and highly flame-resistant freeze-cast foams based on phosphorylated cellulose nanofibrils2018In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 10, no 8, p. 4085-4095Article in journal (Refereed)
    Abstract [en]

    Pure cellulosic foams suffer from low thermal stability and high flammability, limiting their fields of application. Here, light-weight and flame-resistant nanostructured foams are produced by combining cellulose nanofibrils prepared from phosphorylated pulp fibers (P-CNF) with microfibrous sepiolite clay using the freeze-casting technique. The resultant nanocomposite foams show excellent flame-retardant properties such as self-extinguishing behavior and extremely low heat release rates in addition to high flame penetration resistance attributed mainly to the intrinsic charring ability of the phosphorylated fibrils and the capability of sepiolite to form heat-protective intumescent-like barrier on the surface of the material. Investigation of the chemical structure of the charred residue by FTIR and solid state NMR spectroscopy reveals the extensive graphitization of the carbohydrate as a result of dephosphorylation of the modified cellulose and further dehydration due to acidic catalytic effects. Originating from the nanoscale dimensions of sepiolite particles, their high specific surface area and stiffness as well as its close interaction with the phosphorylated fibrils, the incorporation of clay nanorods also significantly improves the mechanical strength and stiffness of the nanocomposite foams. The novel foams prepared in this study are expected to have great potential for application in sustainable building construction.

  • 12.
    Guex, Leonard Gaston
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Sacchi, B.
    Peuvot, Kevin F.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Andersson, Richard L.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Pourrahimi, Amir Masoud
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Ström, Valter
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Farris, S.
    Olsson, Richard T.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Experimental review: chemical reduction of graphene oxide (GO) to reduced graphene oxide (rGO) by aqueous chemistry2017In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 9, no 27, p. 9562-9571Article, review/survey (Refereed)
    Abstract [en]

    The electrical conductivity of reduced graphene oxide (rGO) obtained from graphene oxide (GO) using sodium borohydride (NaBH4) as a reducing agent has been investigated as a function of time (2 min to 24 h) and temperature (20 degrees C to 80 degrees C). Using a 300 mM aqueous NaBH4 solution at 80 degrees C, reduction of GO occurred to a large extent during the first 10 min, which yielded a conductivity increase of 5 orders of magnitude to 10 S m(-1). During the residual 1400 min of reaction, the reduction rate decreased significantly, eventually resulting in a rGO conductivity of 1500 S m(-1). High resolution XPS measurements showed that C/O increased from 2.2 for the GO to 6.9 for the rGO at the longest reaction times, due to the elimination of oxygen. The steep increase in conductivity recorded during the first 8-12 min of reaction was mainly due to the reduction of C-O (e.g., hydroxyl and epoxy) groups, suggesting the preferential attack of the reducing agent on C-O rather than C=O groups. In addition, the specular variation of the percentage content of C-O bond functionalities with the sum of Csp(2) and Csp(3) indicated that the reduction of epoxy or hydroxyl groups had a greater impact on the restoration of the conductive nature of the graphite structure in rGO. These findings were reflected in the dramatic change in the structural stability of the rGO nanofoams produced by freeze-drying. The reduction protocol in this study allowed to achieve the highest conductivity values reported so far for the aqueous reduction of graphene oxide mediated by sodium borohydride. The 4-probe sheet resistivity approach used to measure the electrical conductivity is also, for the first time, presented in detail for filtrate sheet assemblies' of stacked GO/rGO sheets.

  • 13. Hakonen, Aron
    et al.
    Rindzevicius, Tomas
    Schmidt, Michael Stenbæk
    Andersson, Per Ola
    Juhlin, Lars
    Svedendahl, Mikael
    Boisen, Anja
    Käll, Mikael
    Detection of nerve gases using surface-enhanced Raman scattering substrates with high droplet adhesion.2016In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 8, no 3Article in journal (Refereed)
    Abstract [en]

    Threats from chemical warfare agents, commonly known as nerve gases, constitute a serious security issue of increasing global concern because of surging terrorist activity worldwide. However, nerve gases are difficult to detect using current analytical tools and outside dedicated laboratories. Here we demonstrate that surface-enhanced Raman scattering (SERS) can be used for sensitive detection of femtomol quantities of two nerve gases, VX and Tabun, using a handheld Raman device and SERS substrates consisting of flexible gold-covered Si nanopillars. The substrate surface exhibits high droplet adhesion and nanopillar clustering due to elasto-capillary forces, resulting in enrichment of target molecules in plasmonic hot-spots with high Raman enhancement. The results may pave the way for strategic life-saving SERS detection of chemical warfare agents in the field.

  • 14. Hakonen, Aron
    et al.
    Svedendahl, Mikael
    Ogier, Robin
    Yang, Zhong-Jian
    Lodewijks, Kristof
    Verre, Ruggero
    Shegai, Timur
    Andersson, Per Ola
    Käll, Mikael
    Dimer-on-mirror SERS substrates with attogram sensitivity fabricated by colloidal lithography.2015In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 7, no 21Article in journal (Refereed)
    Abstract [en]

    Nanoplasmonic substrates with optimized field-enhancement properties are a key component in the continued development of surface-enhanced Raman scattering (SERS) molecular analysis but are challenging to produce inexpensively in large scale. We used a facile and cost-effective bottom-up technique, colloidal hole-mask lithography, to produce macroscopic dimer-on-mirror gold nanostructures. The optimized structures exhibit excellent SERS performance, as exemplified by detection of 2.5 and 50 attograms of BPE, a common SERS probe, using Raman microscopy and a simple handheld device, respectively. The corresponding Raman enhancement factor is of the order 10(11), which compares favourably to previously reported record performance values.

  • 15.
    Hamedi, Mahiar
    et al.
    Linköping University, Sweden.
    Wigenius, Jens
    Tai, Feng-I
    Björk, Per
    Aili, Daniel
    Polypeptide-guided assembly of conducting polymer nanocomposites2010In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 2, no 10, p. 2058-2061Article in journal (Refereed)
    Abstract [en]

    A strategy for fabrication of electroactive nanocomposites with nanoscale organization, based on self-assembly, is reported. Gold nanoparticles are assembled by a polypeptide folding-dependent bridging. The polypeptides are further utilized to recruit and associate with a water soluble conducting polymer. The polymer is homogenously incorporated into the nanocomposite, forming conducting pathways which make the composite material highly conducting.

  • 16. Hao, Shuwei
    et al.
    Shang, Yunfei
    Li, Deyang
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Yang, Chunhui
    Chen, Guanying
    Enhancing dye-sensitized solar cell efficiency through broadband near-infrared upconverting nanoparticles2017In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 9, no 20, p. 6711-6715Article in journal (Refereed)
    Abstract [en]

    The inability to utilize near infrared (NIR) light has posed a stringent limitation for the efficiencies of most single-junction photovoltaic cells such as dye-sensitized solar cells (DSSCs). Here, we describe a strategy to alleviate the NIR light harvesting problem by upconverting non-responsive NIR light in a broad spectral range (over 190 nm, 670-860 nm) to narrow solar-cell-responsive visible emissions through incorporated dye-sensitized upconversion nanoparticles (DSUCNPs). Unlike typically reported UCNPs with narrow and low NIR absorption, the organic dyes (IR783) anchored on the DSUCNP surface were able to harvest NIR photons broadly and efficiently, and then transfer the harvested energy to the inorganic UCNPs (typically reported), entailing an efficient visible upconversion. We show that the incorporation of DSUCNPs into the TiO2 photoanode of a DSSC is able to elevate its efficiency from 7.573% to 8.568%, enhancing the power conversion efficiency by about 13.1%. We quantified that among the relative efficiency increase, 7.1% arose from the contribution of broad-band upconversion in DSUCNPs (about similar to 3.4 times higher than the highest previously reported value of similar to 2.1%), and 6.0% mainly from the scattering effect of DSUCNPs. Our strategy has immediate implications for the use of DSUCNPs to improve the performance of other types of photovoltaic devices.

  • 17.
    Hjalmarsson, Nicklas
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Wallinder, Daniel
    Glavatskih, Sergei
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.). Univ Ghent, Dept Mech Construct & Prod, B-9052 Zwijnaarde, Belgium.
    Atkin, Rob
    Aastrup, Teodor
    Rutland, Mark W.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. SP Technical Research Institute Sweden, Stockholm, Sweden.
    Weighing the surface charge of an ionic liquid2015In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 7, no 38, p. 16039-16045Article in journal (Refereed)
    Abstract [en]

    Electrochemical quartz crystal microbalance has been used to measure changes in the composition of the capacitive electrical double layer for 1-ethyl-3-methylimidazolium tris(pentafluoroethyl)-trifluorophosphate, an ionic liquid, in contact with a gold electrode surface as a function of potential. The mass difference between the cation and anion means that the technique can effectively "weigh" the surface charge accurately with high temporal resolution. This reveals quantitatively how changing the potential alters the ratio of cations and anions associated with the electrode surface, and thus the charge per unit area, as well as the kinetics associated with these interfacial processes. The measurements reveal that it is diffusion of co-ions into the interfacial region rather than expulsion of counterions that controls the relaxation. The measured potential dependent double layer capacitance experimentally validates recent theoretical predictions for counterion overscreening (low potentials) and crowding (high potentials) at electrode surfaces. This new capacity to quantitatively measure ion composition is critical for ionic liquid applications ranging from batteries, capacitors and electrodeposition through to boundary layer structure in tribology, and more broadly provides new insight into interfacial processes in concentrated electrolyte solutions.

  • 18. Hohn, N.
    et al.
    Schlosser, S. J.
    Bießmann, L.
    Grott, S.
    Xia, S.
    Wang, K.
    Schwartzkopf, M.
    Roth, Stephan V.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites. Deutsches Elektronen-Synchrotron, Germany.
    Müller-Buschbaum, P.
    Readily available titania nanostructuring routines based on mobility and polarity controlled phase separation of an amphiphilic diblock copolymer2018In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 10, no 11, p. 5325-5334Article in journal (Refereed)
    Abstract [en]

    The amphiphilic diblock copolymer polystyrene-block-polyethylene oxide is combined with sol-gel chemistry to control the structure formation of blade-coated foam-like titania thin films. The influence of evaporation time before immersion into a poor solvent bath and polarity of the poor solvent bath are studied. Resulting morphological changes are quantified by scanning electron microscopy (SEM) and grazing incidence small angle X-ray scattering (GISAXS) measurements. SEM images surface structures while GISAXS accesses inner film structures. Due to the correlation of evaporation time and mobility of the polymer template during the phase separation process, a decrease in the distances of neighboring titania nanostructures from 50 nm to 22 nm is achieved. Furthermore, through an increase of polarity of an immersion bath the energetic incompatibility of the hydrophobic block and the solvent can be enhanced, leading to an increase of titania nanostructure distances from 35 nm to 55 nm. Thus, a simple approach is presented to control titania nanostructure in foam-like films prepared via blade coating, which enables an easy upscaling of film preparation.

  • 19. Huang, Kai
    et al.
    Liu, Haichun
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Kraft, Marco
    Shikha, Swati
    Zheng, Xiang
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Würth, Christian
    Resch-Genger, Ute
    Zhang, Yong
    Protected excitation-energy reservoir for efficient upconversion luminescence2017In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 10, no 1, p. 250-259Article in journal (Refereed)
    Abstract [en]

    Lanthanide-doped upconversion nanoparticles (UCNPs) are of great interest for biomedical applications. Currently, the applicability of UCNP bionanotechnology is hampered by the general low luminescence intensity of UCNPs and inefficient energy transfer from UCNPs to surface-bound chromophores used e.g. for photodynamic therapy or analyte sensing. In this work, we address the low efficiency issue by developing versatile core-shell nanostructures, where high-concentration sensitizers and activators are confined in the core- and shell region, representatively for hexagonal NaYF4:Yb, Er UCNPs. After doping concentration optimization, the sensitizer-rich core, is able to harvest/accumulate more excitation energy and generate almost one order of magnitude higher luminescence intensity than conventional homogeneously doped nanostructures. At the same time, the activator ions located in the shell enable a ~6 times more efficient resonant energy transfer from UCNPs to surface-bound acceptor dye molecules due to the short distance between donor-acceptor pairs. Our work provides new insights into the rational design of UCNPs and will greatly increase the general applicability of upconversion nanotechnologies.

  • 20. Jafri, S. H. M.
    et al.
    Lofas, H.
    Fransson, J.
    Blom, T.
    Grigoriev, A.
    Wallner, A.
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Ottosson, H.
    Leifer, K.
    Identification of vibrational signatures from short chains of interlinked molecule-nanoparticle junctions obtained by inelastic electron tunnelling spectroscopy2013In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 5, no 11, p. 4673-4677Article in journal (Refereed)
    Abstract [en]

    Short chains containing a series of metal-molecule-nanoparticle nanojunctions are a nano-material system with the potential to give electrical signatures close to those from single molecule experiments while enabling us to build portable devices on a chip. Inelastic electron tunnelling spectroscopy (IETS) measurements provide one of the most characteristic electrical signals of single and few molecules. In interlinked molecule-nanoparticle (NP) chains containing typically 5-7 molecules in a chain, the spectrum is expected to be a superposition of the vibrational signatures of individual molecules. We have established a stable and reproducible molecule-AuNP multi-junction by placing a few 1,8-octanedithiol (ODT) molecules onto a versatile and portable nanoparticle-nanoelectrode platform and measured for the first time vibrational molecular signatures at complex and coupled few-molecule-NP junctions. From quantum transport calculations, we model the IETS spectra and identify vibrational modes as well as the number of molecules contributing to the electron transport in the measured spectra.

  • 21. Kang, Yu
    et al.
    Zhang, Zhisen
    Shi, Hui
    Zhang, Junqiao
    Liang, Lijun
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. Zhejiang University, China .
    Wang, Qi
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Tu, Yaoquan
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Na+ and K+ ion selectivity by size-controlled biomimetic graphene nanopores2014In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 6, no 18, p. 10666-10672Article in journal (Refereed)
    Abstract [en]

    Because biological ionic channels play a key role in cellular transport phenomena, they have attracted extensive research interest for the design of biomimetic nanopores with high permeability and selectivity in a variety of technical applications. Inspired by the structure of K+ channel proteins, we designed a series of oxygen doped graphene nanopores of different sizes by molecular dynamics simulations to discriminate between K+ and Na+ channel transport. The results from free energy calculations indicate that the ion selectivity of such biomimetic graphene nanopores can be simply controlled by the size of the nanopore; compared to K+, the smaller radius of Na+ leads to a significantly higher free energy barrier in the nanopore of a certain size. Our results suggest that graphene nanopores with a distance of about 3.9 A between two neighboring oxygen atoms could constitute a promising candidate to obtain excellent ion selectivity for Na+ and K+ ions.

  • 22.
    Kousal, Jaroslav
    et al.
    Charles Univ Prague, Dept Macromol Phys, Fac Math & Phys, V Holesovickach 2, Prague 18000, Czech Republic..
    Shelemin, Artem
    Charles Univ Prague, Dept Macromol Phys, Fac Math & Phys, V Holesovickach 2, Prague 18000, Czech Republic..
    Schwartzkopf, Matthias
    Deutsches Elektronen Synchrotron DESY, Notkestr 85, D-22607 Hamburg, Germany..
    Polonskyi, Oleksandr
    Univ Kiel, Chair Multicomponent Mat, Fac Engn, Kiel, Germany..
    Hanus, Jan
    Charles Univ Prague, Dept Macromol Phys, Fac Math & Phys, V Holesovickach 2, Prague 18000, Czech Republic..
    Solar, Pavel
    Charles Univ Prague, Dept Macromol Phys, Fac Math & Phys, V Holesovickach 2, Prague 18000, Czech Republic..
    Vaidulych, Mykhailo
    Charles Univ Prague, Dept Macromol Phys, Fac Math & Phys, V Holesovickach 2, Prague 18000, Czech Republic..
    Nikitin, Daniil
    Charles Univ Prague, Dept Macromol Phys, Fac Math & Phys, V Holesovickach 2, Prague 18000, Czech Republic..
    Pleskunov, Pavel
    Charles Univ Prague, Dept Macromol Phys, Fac Math & Phys, V Holesovickach 2, Prague 18000, Czech Republic..
    Krtous, Zdenek
    Charles Univ Prague, Dept Macromol Phys, Fac Math & Phys, V Holesovickach 2, Prague 18000, Czech Republic..
    Strunskus, Thomas
    Univ Kiel, Chair Multicomponent Mat, Fac Engn, Kiel, Germany..
    Faupel, Franz
    Univ Kiel, Chair Multicomponent Mat, Fac Engn, Kiel, Germany..
    Roth, Stephan V.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. Deutsches Elektronen Synchrotron DESY, Notkestr 85, D-22607 Hamburg, Germany..
    Biederman, Hynek
    Charles Univ Prague, Dept Macromol Phys, Fac Math & Phys, V Holesovickach 2, Prague 18000, Czech Republic..
    Choukourov, Andrei
    Charles Univ Prague, Dept Macromol Phys, Fac Math & Phys, V Holesovickach 2, Prague 18000, Czech Republic..
    Magnetron-sputtered copper nanoparticles: lost in gas aggregation and found by in situ X-ray scattering2018In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 10, no 38, p. 18275-18281Article in journal (Refereed)
    Abstract [en]

    Magnetron discharge in a cold buffer gas represents a liquid-free approach to the synthesis of metal nanoparticles (NPs) with tailored structure, chemical composition and size. Despite a large number of metal NPs that were successfully produced by this method, the knowledge of the mechanisms of their nucleation and growth in the discharge is still limited, mainly because of the lack of in situ experimental data. In this work, we present the results of in situ Small Angle X-ray Scattering measurements performed in the vicinity of a Cu magnetron target with Ar used as a buffer gas. Condensation of atomic metal vapours is found to occur mainly at several mm distance from the target plane. The NPs are found to be captured preferentially within a region circumscribed by the magnetron plasma ring. In this capture zone, the NPs grow to the size of 90 nm whereas smaller ones sized 10-20 nm may escape and constitute a NP beam. Time-resolved measurements of the discharge indicate that the electrostatic force acting on the charged NPs may be largely responsible for their capturing nearby the magnetron.

  • 23.
    Li, Jiantong
    et al.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Östling, Mikael
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Conductivity scaling in supercritical percolation of nanoparticles: not a power law2015In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 7, no 8, p. 3424-3428Article in journal (Refereed)
    Abstract [en]

    The power-law behavior widely observed in supercritical percolation systems of conductive nanoparticles may merely be a phenomenological approximation to the true scaling law not yet discovered. In this work, we derive a comprehensive yet simple scaling law and verify its extensive applicability to various experimental and numerical systems. In contrast to the power law which lacks theoretical backing, the new scaling law is explanatory and predictive, and thereby helpful to gain more new insights into percolation systems of conductive nanoparticles.

  • 24. Li, Xiao-Fei
    et al.
    Lian, Ke-Yan
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Qiu, Qi
    Luo, Yi
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Half-filled energy bands induced negative differential resistance in nitrogen-doped graphene2015In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 7, no 9, p. 4156-4162Article in journal (Refereed)
    Abstract [en]

    Nitrogen-doping brings novel properties and promising applications into graphene, but the underlying mechanism is still in debate. To determine the key factor in motivating the negative differential resistance (NDR) behaviour of nitrogen-doped graphene, the electronic structure and transport properties of an 11-dimer wide nitrogen-doped armchair graphene nanoribbon (N-AGNR) were systematically studied by first principles calculations. Both the effect of interaction between N-dopants and the effect of doping-sublattice on the NDR were examined for the first time. Taking into account the two effects, N-AGNR becomes metallic or semiconducting depending on the doping configuration, and its Fermi level varies in a large range. NDR was firmly verified not to be intrinsic for N-AGNRs. However, it is totally determined by whether nitrogen-doping induces half-filled energy bands (HFEBs) because it is HFEBs that cross the Fermi level and determine the transport properties of N-AGNR under low biases. With the bias increasing, the transmission spectrum near the Fermi level showed a flag shape, and therefore, the corresponding transport channel is totally suppressed at a certain bias, resulting in the NDR behaviour with a configuration-dependent peak-to-valley current ratio (PVCR) up to 10(4). Our findings give new insights into the microscopic mechanism of chemical doping induced NDR behaviour and will be useful in building NDR-based nanodevices in the future.

  • 25. Lim, Chang-Keun
    et al.
    Li, Xin
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Li, Yue
    Drew, Kurt L. M.
    Palafox-Hernandez, J. Pablo
    Tang, Zhenghua
    Baev, Alexander
    Kuzmin, Andrey N.
    Knecht, Marc R.
    Walsh, Tiffany R.
    Swihart, Mark T.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Prasad, Paras N.
    Plasmon-enhanced two-photon-induced isomerization for highly-localized light-based actuation of inorganic/organic interfaces2016In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 8, no 7, p. 4194-4202Article in journal (Refereed)
    Abstract [en]

    Two-photon initiated photo-isomerization of an azobenzene moiety adsorbed on silver nanoparticles (Ag NPs) is demonstrated. The azobenzene is linked to a materials-binding peptide that brings it into intimate contact with the Ag NP surface, producing a dramatic enhancement of its two-photon absorbance. An integrated modeling approach, combining advanced conformational sampling with Quantum Mechanics/Capacitance Molecular Mechanics and response theory, shows that charge transfer and image charges in the Ag NP generate local fields that enhance two-photon absorption of the cis isomer, but not the trans isomer, of adsorbed molecules. Moreover, dramatic local field enhancement is expected near the localized surface plasmon resonance (LSPR) wavelength, and the LSPR band of the Ag NPs overlaps the azobenzene absorbance that triggers cis to trans switching. As a result, the Ag NPs enable two-photon initiated cis to trans isomerization, but not trans to cis isomerization. Confocal anti-Stokes fluorescence imaging shows that this effect is not due to local heating, while the quadratic dependence of switching rate on laser intensity is consistent with a two-photon process. Highly localized two-photon initiated switching could allow local manipulation near the focal point of a laser within a 3D nanoparticle assembly, which cannot be achieved using linear optical processes.

  • 26.
    Liu, Haichun
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Jayakumar, Muthu K. G.
    Huang, Kai
    Wang, Zi
    Zheng, Xiang
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Zhang, Yong
    Phase angle encoded upconversion luminescent nanocrystals for multiplexing applications2017In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 9, no 4, p. 1676-1686Article in journal (Refereed)
    Abstract [en]

    Lanthanide-doped upconversion nanoparticles (UCNPs) are increasingly used as luminescent candidates in multiplexed applications due to their excellent optical properties. Inthepast,several encodingidentities havebeen proposedforUCNPs,includingemissioncolour,intensity ratio between different emissionbands, colourspatial distribution, and luminescencelifetime.In this paper, a new optical encoding dimension for upconversion nanomaterials is developed by exploring their luminescence kinetics, i.e., the phase angle of upconversion luminescence in response to a harmonic-wave excitation. Our theoretical derivation shows that the phase angle is governed jointly by the rise and decay times, characterizing the upconversion luminescence kinetics. Experimentally, a full set of methods are developed to manage the upconversion luminescence kinetics, through which the rise and decay times can be manipulated dependently or independently. Furthermore,a large phase-angle space is achieved in which tens of unique codes can be potentially generated in the same colour channel. Our work greatly extends the multiplexing capacity of UCNPs,and offers newopportunities for their applicationsin a wide range such as microarray assays, bioimaging, anti-counterfeiting, deep tissue multiplexed labelling/detectionand high-density data storage.In addition, the development of thisluminescence kinetics-based optical encoding strategy is also instructive for developing multiplexing techniques using other cascade luminescent systems that inherently lack multi-spectral channels, such as triplet-triplet annihilation molecule pairs.

  • 27.
    Liu, Wen
    et al.
    Zhejiang Univ, Ctr Opt & Electromagnet Res, State Key Lab Modern Opt Instrumentat, Hangzhou 310058, Zhejiang, Peoples R China..
    Wang, Yalun
    Zhejiang Univ, Ctr Opt & Electromagnet Res, State Key Lab Modern Opt Instrumentat, Hangzhou 310058, Zhejiang, Peoples R China..
    Han, Xiao
    Jilin Univ, State Key Lab Supramol Struct & Mat, Changchun 130012, Jilin, Peoples R China..
    Lu, Ping
    Jilin Univ, State Key Lab Supramol Struct & Mat, Changchun 130012, Jilin, Peoples R China..
    Zhu, Liang
    Zhejiang Univ, Interdisciplinary Inst Neurosci & Technol, Hangzhou 310058, Zhejiang, Peoples R China..
    Sun, Chaowei
    Zhejiang Univ, Ctr Opt & Electromagnet Res, State Key Lab Modern Opt Instrumentat, Hangzhou 310058, Zhejiang, Peoples R China..
    Qian, Jun
    Zhejiang Univ, Ctr Opt & Electromagnet Res, State Key Lab Modern Opt Instrumentat, Hangzhou 310058, Zhejiang, Peoples R China..
    He, Sailing
    KTH, School of Electrical Engineering and Computer Science (EECS), Electromagnetic Engineering. Zhejiang Univ, Ctr Opt & Electromagnet Res, State Key Lab Modern Opt Instrumentat, Hangzhou 310058, Zhejiang, Peoples R China.
    Fluorescence resonance energy transfer (FRET) based nanoparticles composed of AIE luminogens and NIR dyes with enhanced three-photon near-infrared emission for in vivo brain angiography2018In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 10, no 21, p. 10025-10032Article in journal (Refereed)
    Abstract [en]

    Near-infrared (NIR) fluorescence is very important for high-contrast biological imaging of high-scattering tissues such as brain tissue. Unfortunately, commercial NIR dyes are excited usually by visible light, and their multi-photon absorption (MPA) cross-sections are small. Here, we design new co-encapsulated NIR nanoparticles (NPs) with a large three-photon (3PA) absorption cross-section. A form of aggregation-induced emission (AIE) luminogen (AIEgen), 2,3-bis(4-(diphenylamino)-[1,1-biphenyl]-4-yl) fumaronitrile (TPATCN), is introduced as the donor, and a form of NIR dye, silicon 2,3-naphthalocyanine bis-(trihexylsilyloxide) (NIR775), is adopted as the acceptor. Under the excitation of a 1550 nm fs laser, TPATCN-NIR775 NPs demonstrated a bright three-photon fluorescence centered at 785 nm. The energy transfer efficiency of the TPATCN-NIR775 NPs was calculated to be as high as 90%, which could be attributed to the good spectral overlap between the emission of TPATCN and the absorption of NIR775. By injection with TPATCN-NIR775 NPs, a vivid 3D reconstruction of mouse brain vasculature was obtained with even small blood vessels clearly visualized. The design strategy used for the co-encapsulated AIE-NIR NPs would be helpful in synthesizing more NIR probes for deep-tissue biological imaging in the future.

  • 28.
    Liu, Yingxin
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. Stockholm Univ, Dept Mat & Environm Chem, S-10691 Stockholm, Sweden..
    Agthe, Michael
    Stockholm Univ, Dept Mat & Environm Chem, S-10691 Stockholm, Sweden.;Univ Hamburg, Ctr Free Electron Laser Sci, D-22761 Hamburg, Germany..
    Salajkova, Michaela
    Univ Oslo, Dept Biosci, N-0371 Oslo, Norway..
    Gordeyeva, Korneliya
    Stockholm Univ, Dept Mat & Environm Chem, S-10691 Stockholm, Sweden..
    Guccini, Valentina
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. Stockholm Univ, Dept Mat & Environm Chem, S-10691 Stockholm, Sweden..
    Fall, Andreas
    Stockholm Univ, Dept Mat & Environm Chem, S-10691 Stockholm, Sweden.;RISE Bioecon, Box 5604, S-11486 Stockholm, Sweden..
    Salazar-Alvarez, German
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. Stockholm Univ, Dept Mat & Environm Chem, S-10691 Stockholm, Sweden..
    Schuetz, Christina
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. Stockholm Univ, Dept Mat & Environm Chem, S-10691 Stockholm, Sweden.;Univ Luxembourg, Phys & Mat Sci Res Unit, L-1511 Luxembourg, Luxembourg..
    Bergstrom, Lennart
    Stockholm Univ, Dept Mat & Environm Chem, S-10691 Stockholm, Sweden..
    Assembly of cellulose nanocrystals in a levitating drop probed by time-resolved small angle X-ray scattering2018In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 10, no 38, p. 18113-18118Article in journal (Refereed)
    Abstract [en]

    Assembly of bio-based nano-sized particles into complex architectures and morphologies is an area of fundamental interest and technical importance. We have investigated the assembly of sulfonated cellulose nanocrystals (CNC) dispersed in a shrinking levitating aqueous drop using time-resolved small angle X-ray scattering (SAXS). Analysis of the scaling of the particle separation distance (d) with particle concentration

  • 29. Lu, Yiping
    et al.
    Gao, Xiaoxia
    Dong, Yong
    Wang, Tongmin
    Chen, Hai-Lin
    Mao, Huahai
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Computational Thermodynamics.
    Zhao, Yonghao
    Jiang, Hui
    Cao, Zhiqiang
    Li, Tingju
    Guo, Sheng
    Preparing bulk ultrafine-microstructure high-entropy alloys via direct solidification2018In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 10, no 4, p. 1912-1919Article in journal (Refereed)
    Abstract [en]

    In the past three decades, nanostructured (NS) and ultrafine-microstructure (UFM) materials have received extensive attention due to their excellent mechanical properties such as high strength. However, preparing low-cost and bulk NS and UFM materials remains to be a challenge, which limits their industrial applications. Here, we report a new strategy to prepare bulk UFM alloys via the direct solidification of high-entropy alloys (HEAs). As a proof of concept, we designed AlCoCrxFeNi (1.8 <= x <= 2.0) HEAs and achieved a complete UFM in bulk materials. The compositional requirements for obtaining the formation of the UFM are highly demanding, necessitating the coupling of near eutectic alloy composition and the high temperature decomposition of supersaturated primary and secondary phases. Our strategy provides a low-cost and highly efficient method to prepare bulk UFM alloys, with great potential to accelerate the engineering application of these materials.

  • 30.
    Monti, Susanna
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Carravetta, Vincenzo
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Decoration of gold nanoparticles with cysteine in solution: reactive molecular dynamics simulations2016In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 8, no 26, p. 12929-12938Article in journal (Refereed)
    Abstract [en]

    The dynamics of gold nanoparticle functionalization by means of adsorption of cysteine molecules in water solution is simulated through classical reactive molecular dynamics simulations based on an accurately parametrized force field. The adsorption modes of the molecules are characterized in detail disclosing the nature of the cysteine-gold interactions and the stability of the final material. The simulation results agree satisfactorily with recent experimental and theoretical data and confirm previous findings for a similar system. The covalent attachments of the molecules to the gold support are all slow physisorptions followed by fast chemisorptions. However, a great variety of binding arrangements can be observed. Interactions with the adsorbate caused surface modulations in terms of adatoms and dislocations which contributed to strengthen the cysteine adsorption.

  • 31. Mukherjee, S. P.
    et al.
    Gliga, A. R.
    Lazzaretto, B.
    Brandner, B.
    Fielden, Matthew
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Vogt, Carmen
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Newman, L.
    Rodrigues, A. F.
    Shao, W.
    Fournier, P. M.
    Toprak, Muhammet Sadaka
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Star, A.
    Kostarelos, K.
    Bhattacharya, K.
    Fadeel, B.
    Graphene oxide is degraded by neutrophils and the degradation products are non-genotoxic2018In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 10, no 3, p. 1180-1188Article in journal (Refereed)
    Abstract [en]

    Neutrophils were previously shown to digest oxidized carbon nanotubes through a myeloperoxidase (MPO)-dependent mechanism, and graphene oxide (GO) was found to undergo degradation when incubated with purified MPO, but there are no studies to date showing degradation of GO by neutrophils. Here we produced endotoxin-free GO by a modified Hummers' method and asked whether primary human neutrophils stimulated to produce neutrophil extracellular traps or activated to undergo degranulation are capable of digesting GO. Biodegradation was assessed using a range of techniques including Raman spectroscopy, transmission electron microscopy, atomic force microscopy, and mass spectrometry. GO sheets of differing lateral dimensions were effectively degraded by neutrophils. As the degradation products could have toxicological implications, we also evaluated the impact of degraded GO on the bronchial epithelial cell line BEAS-2B. MPO-degraded GO was found to be non-cytotoxic and did not elicit any DNA damage. Taken together, these studies have shown that neutrophils can digest GO and that the biodegraded GO is non-toxic for human lung cells.

  • 32. Patra, H. K.
    et al.
    Sharma, Y.
    Islam, M. M.
    Jafari, M. J.
    Natarajan Arul, Murugan
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Kobayashi, H.
    Turner, A. P. F.
    Tiwari, A.
    Inflammation-sensitive in situ smart scaffolding for regenerative medicine2016In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 8, no 39, p. 17213-17222Article in journal (Refereed)
    Abstract [en]

    To cope with the rapid evolution of the tissue engineering field, it is now essential to incorporate the use of on-site responsive scaffolds. Therefore, it is of utmost importance to find new 'Intelligent' biomaterials that can respond to the physicochemical changes in the microenvironment. In this present report, we have developed biocompatible stimuli responsive polyaniline-multiwalled carbon nanotube/poly(N-isopropylacrylamide), (PANI-MWCNT/PNIPAm) composite nanofiber networks and demonstrated the physiological temperature coordinated cell grafting phenomenon on its surface. The composite nanofibers were prepared by a two-step process initiated with an assisted in situ polymerization followed by electrospinning. To obtain a smooth surface in individual nanofibers with the thinnest diameter, the component ratios and electrospinning conditions were optimized. The temperature-gated rearrangements of the molecular structure are characterized by FTIR spectroscopy with simultaneous macromolecular architecture changes reflected on the surface morphology, average diameter and pore size as determined by scanning electron microscopy. The stimuli responsiveness of the nanofibers has first been optimized with computational modeling of temperature sensitive components (coil-like and globular conformations) to tune the mechanism for temperature dependent interaction during in situ scaffolding with the cell membrane. The nanofiber networks show excellent biocompatibility, tested with fibroblasts and also show excellent sensitivity to inflammation to combat loco-regional acidosis that delay the wound healing process by an in vitro model that has been developed for testing the proposed responsiveness of the composite nanofiber networks. Cellular adhesion and detachment are regulated through physiological temperature and show normal proliferation of the grafted cells on the composite nanofibers. Thus, we report for the first time, the development of physiological temperature gated inflammation-sensitive smart biomaterials for advanced tissue regeneration and regenerative medicine.

  • 33. Paul, Neelima
    et al.
    Metwalli, Ezzeldin
    Yao, Yuan
    Schwartzkopf, Matthias
    Yu, Shun
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. Technische Universität München, Germany.
    Roth, Stephan V.
    Mueller-Buschbaum, Peter
    Paul, Amitesh
    Templating growth of gold nanostructures with a CdSe quantum dot array2015In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 7, no 21, p. 9703-9714Article in journal (Refereed)
    Abstract [en]

    In optoelectronic devices based on quantum dot arrays, thin nanolayers of gold are preferred as stable metal contacts and for connecting recombination centers. The optimal morphology requirements are uniform arrays with precisely controlled positions and sizes over a large area with long range ordering since this strongly affects device performance. To understand the development of gold layer nanomorphology, the detailed mechanism of structure formation are probed with time-resolved grazing incidence small-angle X-ray scattering (GISAXS) during gold sputter deposition. Gold is sputtered on a CdSe quantum dot array with a characteristic quantum dot spacing of approximate to 7 nm. In the initial stages of gold nanostructure growth, a preferential deposition of gold on top of quantum dots occurs. Thus, the quantum dots act as nucleation sites for gold growth. In later stages, the gold nanoparticles surrounding the quantum dots undergo a coarsening to form a complete layer comprised of gold-dot clusters. Next, growth proceeds dominantly via vertical growth of gold on these gold-dot clusters to form an gold capping layer. In this capping layer, a shift of the cluster boundaries due to ripening is found. Thus, a templating of gold on a CdSe quantum dot array is feasible at low gold coverage.

  • 34. Qiu, Hailong
    et al.
    Chen, Guanying
    Fan, Rongwei
    Yang, Liming
    Liu, Cheng
    Hao, Shuwei
    Sailor, Michael J.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Yang, Chunhui
    Prasad, Paras N.
    Intense ultraviolet upconversion emission from water-dispersed colloidal YF3:Yb3+/Tm3+ rhombic nanodisks2014In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 6, no 2, p. 753-757Article in journal (Refereed)
    Abstract [en]

    Intense ultraviolet upconversion emission has been observed in water-dispersed uniform rhombic nanodisks (side length of similar to 14 nm and thickness of similar to 2.5 nm) of YF3 co-doped with Yb3+ sensitizer and Tm3+ activator ions, when excited at similar to 980 nm.

  • 35. Shao, Wei
    et al.
    Chen, Guanying
    Ohulchanskyy, Tymish Y.
    Yang, Chunhui
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Prasad, Paras N.
    A core-multiple shell nanostructure enabling concurrent upconversion and quantum cutting for photon management2017In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 9, no 5, p. 1934-1941Article in journal (Refereed)
    Abstract [en]

    Photon management enables the manipulation of the number of input photons by conversion of two or more light quanta into one (upconversion) or vice versa (quantum cutting). Simultaneous realization of both these processes in a single unit provides unique opportunities of efficient utilization of photons throughout a broad spectral range. Yet, concurrent realization of these two parallel optical processes in one single unit remains elusive, limiting its impact on many existing or possible future applications such as for panchromatic photovoltaics. Here, we describe an epitaxial active core/inert shell/active shell/inert shell fluoride nanostructure to implement upconversion and quantum cutting within spatially confined and isolated rare-earth-doped active domains. The core area transforms infrared photons through trivalent erbium (Er3+) ions into three-and two-photon upconverted visible and near infrared luminescence, while the second shell domain splits an excitation photon into two near infrared photons through cooperative quantum cutting from one trivalent terbium ion (Tb3+) to two trivalent ytterbium ions (Yb3+). The inert layer in between the active domains is able to effectively suppress the destructive interference between upconversion and quantum cutting, while the outermost inert shell is able to eliminate surfacerelated quenching. This design enables the colloidal core/multishell nanoparticles to have an upconversion quantum yield of similar to 1.6%, and to have a luminescence yield of the quantum cutting process as high as similar to 130%. This work constitutes a solid step for flexible photon management in a single nanostructure, and has an implication for photonic applications beyond photovoltaics.

  • 36.
    Smirnov, Serguei
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems.
    Anoshkin, Ilya V.
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems.
    Demchenko, Petr
    ITMO University.
    Gomon, Daniel
    ITMO University.
    Lioubtchenko, Dmitri V.
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems.
    Khodzitsky, Mikhail
    ITMO University.
    Oberhammer, Joachim
    KTH, School of Electrical Engineering and Computer Science (EECS), Micro and Nanosystems.
    Optically controlled dielectric properties of single-walled carbon nanotubes for terahertz wave applications2018In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 10, no 26, p. 12291-12296Article in journal (Refereed)
    Abstract [en]

    Materials with tunable dielectric properties are valuable for a wide range of electronic devices, but are often lossy at terahertz frequencies. Here we experimentally report the tuning of the dielectric properties of single-walled carbon nanotubes under light illumination. The effect is demonstrated by measurements of impedance variations at low frequency as well as complex dielectric constant variations in the wide frequency range of 0.1-1 THz by time domain spectroscopy. We show that the dielectric constant is significantly modified for varying light intensities. The effect is also practically applied to phase shifters based on dielectric rod waveguides, loaded with carbon nanotube layers. The carbon nanotubes are used as tunable impedance surface controlled by light illumination, in the frequency range of 75-500 GHz. These results suggest that the effect of dielectric constant tuning with light, accompanied by low transmission losses of the carbon nanotube layer in such an ultra-wide band, may open up new directions for the design and fabrication of novel Terahertz and optoelectronic devices.

  • 37.
    Smith, Anderson D.
    et al.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Elgammal, Karim
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Niklaus, Frank
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Delin, Anna
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF. KTH, School of Electrical Engineering (EES), Micro and Nanosystems. KTH, Centres, SeRC - Swedish e-Science Research Centre.
    Fischer, Andreas C.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Vaziri, Sam
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Forsberg, Fredrik
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Råsander, Mikael
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF. Univ London Imperial Coll Sci Technol & Med, Dept Mat, England.
    Hugosson, Håkan
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Bergqvist, Lars
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF. KTH, Centres, SeRC - Swedish e-Science Research Centre.
    Schröder, Stephan
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Kataria, Satender
    Östling, Mikael
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Lemme, Max C.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits. Univ Siegen, D-57076 Siegen, Germany.
    Resistive graphene humidity sensors with rapid and direct electrical readout2015In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 7, no 45, p. 19099-19109Article in journal (Refereed)
    Abstract [en]

    We demonstrate humidity sensing using a change of the electrical resistance of single-layer chemical vapor deposited (CVD) graphene that is placed on top of a SiO2 layer on a Si wafer. To investigate the selectivity of the sensor towards the most common constituents in air, its signal response was characterized individually for water vapor (H2O), nitrogen (N-2), oxygen (O-2), and argon (Ar). In order to assess the humidity sensing effect for a range from 1% relative humidity (RH) to 96% RH, the devices were characterized both in a vacuum chamber and in a humidity chamber at atmospheric pressure. The measured response and recovery times of the graphene humidity sensors are on the order of several hundred milliseconds. Density functional theory simulations are employed to further investigate the sensitivity of the graphene devices towards water vapor. The interaction between the electrostatic dipole moment of the water and the impurity bands in the SiO(2)d substrate leads to electrostatic doping of the graphene layer. The proposed graphene sensor provides rapid response direct electrical readout and is compatible with back end of the line (BEOL) integration on top of CMOS-based integrated circuits.

  • 38. Sun, Weiwei
    et al.
    Li, Yunguo
    Wang, Baotian
    Jiang, Xue
    Katsnelson, Mikhail I.
    Korzhavyi, Pavel
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Eriksson, Olle
    Di Marco, Igor
    A new 2D monolayer BiXene, M2C (M = Mo, Tc, Os)2016In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 8, no 34, p. 15753-15762Article in journal (Refereed)
    Abstract [en]

    The existence of BiXenes, a new family of 2D monolayers, is hereby predicted. Theoretically, BiXenes have 1H symmetry (P (6) over bar m2) and can be formed from the 4d/5d binary carbides. As the name suggests, they are close relatives of MXenes, which instead have 1T symmetry (P (3) over bar m1). The newly found BiXenes, as well as some new MXenes, are shown to have formation energies close to that of germanene, which suggests that these materials should be possible to be synthesised. Among them, we illustrate that 1H-Tc2C and 1T-Mo2C are dynamically stable at 0 K, while 1H-Mo2C, 1T-Tc2C, 1H-Os2C, and 1T-Rh2C are likely to be stabilised via strain or temperature. In addition, the nature of the chemical bonding is analysed, emphasizing that the covalency between the transition metal ions and carbon is much stronger in BiXenes than in MXenes. The emergence of BiXenes can not only open up a new era of conducting 2D monolayers, but also provide good candidates for carrier materials aimed at energy storage and spintronic devices that have already been unveiled in MXenes.

  • 39.
    Träger, Andrea
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Pendergraph, Samuel A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Pettersson, Torbjörn
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Halthur, Tobias
    Nylander, Tommy
    Carlmark, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Strong and tuneable wet adhesion with rationally designed layer-by-layer assembled triblock copolymer films2016In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 8, no 42, p. 18204-18211Article in journal (Refereed)
    Abstract [en]

    this study the wet adhesion between Layer-by-Layer (LbL) assembled films of triblock copolymer micelles was investigated. Through the LbL assembly of triblock copolymer micelles with hydrophobic, low glass transition temperature (T-g) middle blocks and ionic outer blocks, a network of energy dissipating polymer chains with electrostatic interactions serving as crosslinks can be built. Four triblock copolymers were synthesized through Atom Transfer Radical Polymerisation (ATRP). One pair had a poly(2-ethyl-hexyl methacrylate) middle block with cationic or anionic outer blocks. The other pair contained the same ionic outer blocks but poly(n-butyl methacrylate) as the middle block. The wet adhesion was evaluated with colloidal probe AFM. To our knowledge, wet adhesion of the magnitude measured in this study has not previously been measured on any polymer system with this technique. We are convinced that this type of block copolymer system grants the ability to control the geometry and adhesive strength in a number of nano-and macroscale applications.

  • 40.
    Vaziri, Sam
    et al.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Belete, M.
    Dentoni Litta, Eugenio
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Smith, Anderson D.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Lupina, G.
    Lemme, Max C.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits. University of Siegen, Germany.
    Östling, Mikael
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Bilayer insulator tunnel barriers for graphene-based vertical hot-electron transistors2015In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 7, no 30, p. 13096-13104Article in journal (Refereed)
    Abstract [en]

    Vertical graphene-based device concepts that rely on quantum mechanical tunneling are intensely being discussed in the literature for applications in electronics and optoelectronics. In this work, the carrier transport mechanisms in semiconductor-insulator-graphene (SIG) capacitors are investigated with respect to their suitability as electron emitters in vertical graphene base transistors (GBTs). Several dielectric materials as tunnel barriers are compared, including dielectric double layers. Using bilayer dielectrics, we experimentally demonstrate significant improvements in the electron injection current by promoting Fowler-Nordheim tunneling (FNT) and step tunneling (ST) while suppressing defect mediated carrier transport. High injected tunneling current densities approaching 103 A cm(-2) (limited by series resistance), and excellent current-voltage nonlinearity and asymmetry are achieved using a 1 nm thick high quality dielectric, thulium silicate (TmSiO), as the first insulator layer, and titanium dioxide (TiO2) as a high electron affinity second layer insulator. We also confirm the feasibility and effectiveness of our approach in a full GBT structure which shows dramatic improvement in the collector on-state current density with respect to the previously reported GBTs. The device design and the fabrication scheme have been selected with future CMOS process compatibility in mind. This work proposes a bilayer tunnel barrier approach as a promising candidate to be used in high performance vertical graphene-based tunneling devices.

  • 41. Verre, R
    et al.
    Maccaferri, N
    Fleischer, K
    Svedendahl, Mikael
    Chalmers University of Technology, Sweden.
    Odebo Länk, N.
    Dmitriev, A.
    Vavassori, P.
    Shvets, I. V.
    Käll, M.
    Polarization conversion-based molecular sensing using anisotropic plasmonic metasurfaces2016In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 8, no 20, p. 10576-10581Article in journal (Refereed)
    Abstract [en]

    Anisotropic media induce changes in the polarization state of transmitted and reflected light. Here we combine this effect with the refractive index sensitivity typical of plasmonic nanoparticles to experimentally demonstrate self-referenced single wavelength refractometric sensing based on polarization conversion. We fabricated anisotropic plasmonic metasurfaces composed of gold dimers and, as a proof of principle, measured the changes in the rotation of light polarization induced by biomolecular adsorption with a surface sensitivity of 0.2 ng cm(-2). We demonstrate the possibility of miniaturized sensing and we show that experimental results can be reproduced by analytical theory. Various ways to increase the sensitivity and applicability of the sensing scheme are discussed.

  • 42.
    Wåhlander, Martin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Nilsson, Fritjof
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Carlmark, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Gedde, Ulf W
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Edmondson, Steve
    School of Materials, University of Manchester.
    Malmström, Eva
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Correction: Hydrophobic matrix-free graphene-oxide composites with isotropic and nematic states2016In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 8, p. 13522-13522Article in journal (Refereed)
    Abstract [en]

    Correction in Figure 8 for ‘Hydrophobic matrix-free graphene-oxide composites with isotropic and nematic states’ by Martin Wåhlander, et al., Nanoscale, 2016, DOI: 10.1039/c6nr01502f

  • 43.
    Wåhlander, Martin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Nilsson, Fritjof
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Carlmark, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Gedde, Ulf W
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Edmondson, Steve
    Malmström, Eva
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Hydrophobic matrix-free graphene-oxide composites with isotropic and nematic states2016In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 8, p. 14730-14745Article in journal (Refereed)
    Abstract [en]

    We demonstrate a novel route to synthesise hydrophobic matrix-free composites of polymer-grafted graphene oxide (GO) showing isotropic or nematic alignment and shape-memory effects. For the first time, a cationic macroinitiator (MI) has been immobilised on anionic GO and subsequently grafted with hydrophobic polymer grafts. Dense grafts of PBA, PBMA and PMMA with a wide range of average graft lengths (MW: 1–440 kDa) were polymerised by surface-initiated controlled radical precipitation polymerisation from the statistical MI. The surface modification is designed similarly to bimodal graft systems, where the cationic MI generates nanoparticle repulsion, similar to dense short grafts, while the long grafts offer miscibility in non-polar environments and cohesion. The state-of-the-art dispersions of grafted GO were in the isotropic state. Transparent and translucent matrix-free GO-composites could be melt-processed directly using only grafted GO. After processing, birefringence due to nematic alignment of grafted GO was observed as a single giant Maltese cross, 3.4 cm across. Permeability models for composites containing aligned 2D-fillers were developed, which were compared with the experimental oxygen permeability data and found to be consistent with isotropic or nematic states. The storage modulus of the matrix-free GO-composites increased with GO content (50% increase at 0.67 wt%), while the significant increases in the thermal stability (up to 130 °C) and the glass transition temperature (up to 17 °C) were dependent on graft length. The tuneable matrix-free GO-composites with rapid thermo-responsive shape-memory effects are promising candidates for a vast range of applications, especially selective membranes and sensors.

  • 44.
    Xia, Senlin
    et al.
    Tech Univ Munich, Lehrstuhl Funkt Mat, Phys Dept, James Franck Str 1, D-85748 Garching, Germany..
    Song, Lin
    Tech Univ Munich, Lehrstuhl Funkt Mat, Phys Dept, James Franck Str 1, D-85748 Garching, Germany..
    Koerstgens, Volker
    Tech Univ Munich, Lehrstuhl Funkt Mat, Phys Dept, James Franck Str 1, D-85748 Garching, Germany..
    Opel, Matthias
    Bayerische Akad Wissensch, Walther Meissner Inst, Walther Meissner Str 8, D-85748 Garching, Germany..
    Schwartzkopf, Matthias
    Deutsch Elekt Synchrotron DESY, Notkestr 85, D-22603 Hamburg, Germany..
    Roth, Stephan V.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. Deutsch Elekt Synchrotron DESY, Notkestr 85, D-22603 Hamburg, Germany.
    Mueller-Buschbaum, Peter
    Tech Univ Munich, Lehrstuhl Funkt Mat, Phys Dept, James Franck Str 1, D-85748 Garching, Germany..
    Magnetic nanoparticle-containing soft-hard diblock copolymer films with high order2018In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 10, no 25, p. 11930-11941Article in journal (Refereed)
    Abstract [en]

    For sensor applications, superparamagnetic anisotropy is an indispensable property, which is typically achieved by employing an external field to guide the arrangement of magnetic nanoparticles (NPs). In the present investigation, the diblock copolymer polystyrene-block-poly(N-isopropylacrylamide) (PS-b-PNIPAM) is printed as a template to localize magnetic iron oxide NPs without any external field. Via microphase separation, cylindrical nanostructures of PS in a PNIPAM matrix are obtained, aligned perpendicular to the substrate. Since the magnetite NPs (Fe3O4) are functionalized with hydrophobic organic chains showing affinity to the PS blocks, they can selectively aggregate inside the PS cylinders. Moreover, solvent vapor annealing allows the achievement of nanostructures inside the hybrid system with a very high order, even at a high NP loading. Therefore, NPs can accumulate within PS domains to form perpendicularly aligned aggregates with high periodicity. The magnetic properties of the hybrid films are determined at various temperatures in two orthogonal directions (with PS cylinders vertical and parallel to the applied magnetic field). All hybrid films show superparamagnetism and a remarkable magnetic anisotropy is achieved at certain NP concentrations. This investigation shows a facile route to prepare superparamagnetic films with magnetic anisotropy and offers a novel possibility to future magnetic sensor fabrication.

  • 45.
    Xie, Zhen
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Theoretical Chemistry and Biology. Shandong Normal Univ, Sch Phys & Elect, Shandong Prov Key Lab Med Phys & Image Proc Techo, Jinan 250014, Shandong, Peoples R China.
    Duan, Sai
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Theoretical Chemistry and Biology.
    Tian, Guangjun
    Yanshan Univ, Coll Sci, Qinhuangdao 066004, Peoples R China..
    Wang, Chuan-Kui
    Shandong Normal Univ, Sch Phys & Elect, Shandong Prov Key Lab Med Phys & Image Proc Techo, Jinan 250014, Shandong, Peoples R China..
    Luo, Yi
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Theoretical Chemistry and Biology. Univ Sci & Technol China, Hefei Natl Lab Phys Sci Microscale, Hefei 230026, Anhui, Peoples R China..
    Theoretical modeling of tip-enhanced resonance Raman images of switchable azobenzene molecules on Au(111)2018In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 10, no 25, p. 11850-11860Article in journal (Refereed)
    Abstract [en]

    With a highly localized plasmonic field, tip-enhanced Raman spectroscopy (TERS) images have reached atomic-scale resolution, providing an optical means to explore the structure of a single molecule. We have applied the recently developed theoretical method to simulate the TERS images of trans and cis azobenzene as well as its derivatives on Au(111). Our theoretical results reveal that when the first excited state is resonantly excited, TERS images from a highly confined plasmonic field can effectively distinguish the isomer configurations of the adsorbates. The decay of the plasmonic field along the surface normal can be further used to distinguish different nonplanar cis configurations. Moreover, subtle characteristics of different molecular configurations can also be identified from the TERS images of other resonant excited states with a super-high confined plasmonic field. These findings serve as good references for future TERS experiments on molecular isomers.

  • 46. Xie, Zhen
    et al.
    Duan, Sai
    Wang, Chuan-Kui
    Luo, Yi
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. University of Science and Technology of China.
    Lighting up long-range charge-transfer states by a localized plasmonic field2017In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 9, no 46, p. 18189-18193Article in journal (Refereed)
    Abstract [en]

    The long-range charge-transfer states in a donor-acceptor system exhibit well separated electron-hole pairs, but are often difficult to achieve by optical means owing to a very small overlap between the wave functions of the donor and acceptor. We have found that the introduction of a spatially confined plasmon can enhance the transition probability to the long-range charge-transfer states as it can effectively break the intrinsic symmetry selection rule imposed on the system. Meanwhile, the intensity borrowed from local excitations could also be selectively promoted, allowing the manipulation of the excited quantum states. In addition, our calculations reveal that the donor and acceptor moieties can be unambiguously visualized in real space by tip-enhanced resonance Raman images. These findings can benefit light-harvesting and also be readily extended to diverse optical processes.

  • 47. Xu, Xiaobao
    et al.
    Zhang, Bingyan
    Cui, Jin
    Xiong, Dehua
    Shen, Yan
    Chen, Wei
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Cheng, Yibing
    Wang, Mingkui
    Efficient p-type dye-sensitized solar cells based on disulfide/thiolate electrolytes2013In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 5, no 17, p. 7963-7969Article in journal (Refereed)
    Abstract [en]

    Herein, an organic redox couple 1-methy-1H-tetrazole-5-thiolate (T-) and its disulfide dimer (T-2) redox shuttle, as an electrolyte, is introduced in a p-type dye-sensitized solar cell (DSC) on the basis of an organic dye (P1) sensitizer and nanocrystal CuCrO2 electrode. Using this iodide-free transparent redox electrolyte in conjunction with the sensitized heterojunction, we achieve a high open-circuit voltage of over 300 mV. An optimal efficiency of 0.23% is obtained using a CoS counter electrode and an optimized electrolyte composition under AM 1.5 G 100 mW cm(-2) light illumination which, to the best of our knowledge, represents the highest efficiency that has so far been reported for p-type DSCs using organic redox couples.

  • 48. Yang, Quanling
    et al.
    Saito, Tsuguyuki
    Berglund, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites.
    Isogai, Akira
    Cellulose nanofibrils improve the properties of all-cellulose composites by the nano-reinforcement mechanism and nanofibril-induced crystallization2015In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 7, no 42, p. 17957-17963Article in journal (Refereed)
    Abstract [en]

    All-cellulose nanocomposite films containing crystalline TEMPO-oxidized cellulose nanofibrils (TOCNs) of 0-1 wt% were fabricated by mixing aqueous TOCN dispersions with alkali/urea/cellulose (AUC) solutions at room temperature. The mixtures were cast on glass plates, soaked in an acid solution, and the regenerated gel-like films were washed with water and then dried. The TOCN did not form agglomerates in the composites, and had the structure of TOCN-COOH, forming hydrogen bonds with the hydroxyl groups of the regenerated cellulose molecules. X-ray diffraction analysis revealed that the matrix cellulose molecules increased the cellulose II crystal size upon incorporation of TOCN. As a result, the TOCN/AUC composite films had high Young's modulus, tensile strength, thermal stability and oxygen-barrier properties. The TOCN/AUC composite films are promising all-cellulose nanocomposites for versatile applications as new bio-based materials.

  • 49.
    Yuan, Sijian
    et al.
    Fudan Univ, Ctr Micronano Syst, State Key Lab ASIC & Syst, SIST, Shanghai 200433, Peoples R China..
    Wang, Jiao
    Fudan Univ, Ctr Micronano Syst, State Key Lab ASIC & Syst, SIST, Shanghai 200433, Peoples R China..
    Yang, Kunlong
    KTH, School of Electrical Engineering and Computer Science (EECS). IPack VINN Excellence Ctr, Royal Inst Technol KTH, S-16440 Stockholm, Sweden..
    Wang, Pengfei
    Fudan Univ, Ctr Micronano Syst, State Key Lab ASIC & Syst, SIST, Shanghai 200433, Peoples R China..
    Zhang, Xin
    Fudan Univ, Ctr Micronano Syst, State Key Lab ASIC & Syst, SIST, Shanghai 200433, Peoples R China..
    Zhan, Yiqiang
    Fudan Univ, Ctr Micronano Syst, State Key Lab ASIC & Syst, SIST, Shanghai 200433, Peoples R China..
    Zheng, Li-rong
    KTH. Fudan Univ, Ctr Micronano Syst, State Key Lab ASIC & Syst, SIST, Shanghai 200433, Peoples R China.;IPack VINN Excellence Ctr, Royal Inst Technol KTH, S-16440 Stockholm, Sweden..
    High efficiency MAPbI(3-x)Cl(x) perovskite solar cell via interfacial passivation2018In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 10, no 40, p. 18909-18914Article in journal (Refereed)
    Abstract [en]

    The trap states at the interface between perovskite and charge-transport layer have a great influence on the performance of perovskite solar cells. Here, a high efficiency MAPbI(3-x)Cl(x) perovskite solar cell has been demonstrated, by introducing a thin layer of LiF or PbF2 between the SnO2/perovskite. Improved charge collection and reduced interfacial charge recombination are realized, leading to remarkable rises of both open-circuit voltage (V-oc) and short-circuit current (J(sc)). This successful interfacial passivation paved a new way to fabricate high performance perovskite solar cells with large V-oc.

  • 50. Zhang, Lei
    et al.
    Hao, Jiaming
    Ye, Huapeng
    Yeo, Swee Ping
    Qiu, Min
    Zouhdi, Said
    KTH, School of Information and Communication Technology (ICT).
    Qiu, Cheng-Wei
    Theoretical realization of robust broadband transparency in ultrathin seamless nanostructures by dual blackbodies for near infrared light2013In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 5, no 8, p. 3373-3379Article in journal (Refereed)
    Abstract [en]

    We propose a counter-intuitive mechanism of constructing an ultrathin broadband transparent device with two perfect blackbodies. By introducing hybridization of plasmon modes, resonant modes with different symmetries coexist in this system. A broadband transmission spectrum in the near infrared regime is achieved through controlling their coupling strengths, which is governed by the thickness of high refractive index layer. Meanwhile, the transparency bandwidth is found to be tunable in a large range by varying the geometric dimension. More significantly, from the point view of applications, the proposed method of achieving broadband transparency can perfectly tolerate the misalignment and asymmetry of periodic nanoparticles on the top and bottom, which is empowered by the unique dual of coupling-in and coupling-out processes within the pair of blackbodies. Moreover, roughness has little influence on its transmission performance. According to the coupled mode theory, the distinguished transmittance performance is physically interpreted by the radiative decay rate of the entire system. In addition to the feature of uniquely robust broadband transparency, such a ultrathin seamless nanostructure ( in the presence of a uniform silver layer) also provides polarization-independent and angle-independent operations. Therefore, it may power up a wide spectrum of exciting applications in thin film protection, touch screen techniques, absorber-emitter transformation, etc.

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