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  • 1. Al-Bataineh, Sameer A.
    et al.
    Luginbuehl, Reto
    Textor, Marcus
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Covalent Immobilization of Antibacterial Furanones via Photochemical Activation of Perfluorophenylazide2009In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 25, no 13, p. 7432-7437Article in journal (Refereed)
    Abstract [en]

    N-(3-Trimethoxysilylpropyl)-4-azido-2,3,5,6-tetrafluorobenzamide (PFPA-silane) was used as a photoactive crosslinker to immobilize antibacterial furanone molecules on silicon oxide surfaces. This immobilization strategy is useful, especially for substrates and molecules that lack reactive functional groups. To this end, cleaned wafers were initially incubated in solutions of different concentrations of PFPA-silane to form a monolayer presenting azido groups on the surface. The functionalized surfaces were then treated with a furanone solution followed by illumination with UV light and extensive rinsing with ethanol to remove noncovalently adhered molecules, In the presented study, we demonstrate the ability to control the surface density of the immobilized furanone molecules by adjusting the concentration of PFPA-silane solution used for surface functionalization using complementary surface analytical techniques. The fluorine in PFPA-silane and the bromine in furanone molecules were convenient markers for the XPS study. The ellipsometric layer thickness of the immobilized furanone molecules on the surface decreased with decreasing PFPA-silane concentration, which correlated with a decline of water contact angle as a sign of film collapse. The intensity of characteristic azide vibration in the MTR IR spectra was monitored as a function of PFPA-silane concentration, and the peak disappeared completely after furanone application followed by UV irradiation. As a complementary technique to XPS, TOF-SIMS provided valuable information on the chemical and molecular structure of the modified surfaces and spatial distribution of the immobilized furanone molecules. Finally, this report presents a convenient, reproducible, and robust strategy to design antibacterial coating based on furanone compounds for applications in human health care.

  • 2. Chada, Sailaja
    et al.
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Self-assembled nanostructures from homopolymer induced by UV and solvent exposure2008In: Soft Matter, ISSN 1744-683X, E-ISSN 1744-6848, Vol. 4, no 11, p. 2164-2167Article in journal (Refereed)
    Abstract [en]

    A simple method for creating self-assembled nanostructures using a single polymer system is reported. When spin-coated polystyrene thin films were irradiated with UV light and treated with toluene, unique nanostructures were observed, evolving from star-shaped networks to arrays of concentric circles. The nanostructure formation is a result of differential responses of crosslinked and oxidized products to the solvent by a combined effect of phase separation and solvent swelling. The nanostructures were observed for polymers of different molecular weights, films of different thicknesses, and on various substrates.

  • 3. Chaudhary, Shilpi
    et al.
    Kamra, Tripta
    Uddin, Khan Mohammad Ahsan
    Snezhkova, Olesia
    Jayawardena, H. Surangi N.
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Montelius, Lars
    Schnadt, Joachim
    Ye, Lei
    Controlled short-linkage assembly of functional nano-objects2014In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 300, p. 22-28Article in journal (Refereed)
    Abstract [en]

    In this work, we report a method that allows the deterministic, photo-controlled covalent assembly of nanoparticles directly on surface. As a model system, we study the conjugation of molecularly imprinted polymer (MIP) nanoparticles on a glass surface and confirm that the immobilized nanoparticles maintain their molecular recognition functionality. The glass slide was first modified with perfluorophenylazide and then used to bind MIP nanoparticles under UV irradiation. After each step the surface was analyzed by water contact angle measurement, fluorescence microscopy, scanning electron microscopy, and/or synchrotron-based X-ray photoelectron spectroscopy. The MIP nanoparticles immobilized on the glass surface remained stable and maintained specific binding for the template molecule, propranolol. The method developed in this work allows MIP nanoparticles to be directly coupled to a flat surface, offering a straightforward means to construct robust chemical sensors. Using the reported photo conjugation method, it is possible to generate patterned assembly of nanoparticles using a photomask. Since perfluorophenylazide-based photochemistry works with all kinds of organic material, the method developed in this work is expected to enable immobilization of not only MIPs but also other kinds of organic and inorganic-organic core-shell particles for various applications involving photon or electron transfer.

  • 4. Chen, Xuan
    et al.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. University of Massachusetts Lowell, United States .
    Glyconanomaterials: Emerging applications in biomedical research2014In: Nano Reseach, ISSN 1998-0124, E-ISSN 1998-0000, Vol. 7, no 10, p. 1381-1403Article, review/survey (Refereed)
    Abstract [en]

    Carbohydrates constitute the most abundant organic matter in nature, serving as structural components and energy sources, and mediating a wide range of cellular activities. The emergence of nanomaterials with distinct optical, magnetic, and electronic properties has witnessed a rapid adoption of these materials for biomedical research and applications. Nanomaterials of various shapes and sizes having large specific surface areas can be used as multivalent scaffolds to present carbohydrate ligands. The resulting glyconanomaterials effectively amplify the glycan-mediated interactions, making it possible to use these materials for sensing, imaging, diagnosis, and therapy. In this review, we summarize the synthetic strategies for the preparation of various glyconanomaterials. Examples are given where these glyconanomaterials have been used in sensing and differentiation of proteins and cells, as well as in imaging glycan-medicated cellular responses.

  • 5. Chen, Y. C.
    et al.
    Barzier, J. J.
    Yan, Mingdi
    Department of Chemistry, PSU, Portland, OR.
    Prahl, S. A.
    Evaluation of molecularly imprinted polyurethane as an optical waveguide for PAH sensing2004In: NANOSENSING: MATERIALS AND DEVICES, 2004, Vol. 5593, p. 513-520Conference paper (Refereed)
    Abstract [en]

    We developed a numerical model for the fluorescence output efficiency of a molecularly imprinted polymer (MIP) waveguide sensing system. A polyurethane waveguide imprinted with a polycyclic aromatic hydrocarbon (PAH) molecule was fabricated using micromolding in capillaries. The coupling of light into a 5 mm long MIP segment was verified by comparing the output transmission signals of a deuterium lamp from the MIP waveguide collected by, an optical fiber with the background lamp signals collected by the same optical fiber. It was found that polyurethane MIP was an effective waveguide but absorbed much shorter wavelengths, especially ill the UV region. thereby the transmission of light appeared orange/red in color. The high background absorption of polyurethane in the spectrometric regions of interest was found to be a critical problem for sensor sensitivity. Our numerical model shows that the fluorescence output is only 2 X 10(-6) of the input excitation for 25 mM anthracene for a 5mm polyurethane waveguide. A 10 fold decrease of background absorption will increase the fluorescence output 250 times.

  • 6. Chen, Y. C.
    et al.
    Brazier, J. J.
    Yan, Mingdi
    Department of Chemistry, Portland State University.
    Bargo, P. R.
    Prahl, S. A.
    Fluorescence-based optical sensor design for molecularly imprinted polymers2004In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 102, no 1, p. 107-116Article in journal (Refereed)
    Abstract [en]

    A Monte Carlo model was developed to analyze the sensitivity and the performance of a fluorescence-based molecularly imprinted polymer (MIP) sensor. The MIP sensor consisted of highly cross-linked polyurethane containing anthracene binding sites coated on a transparent substrate. The optical properties of MlPs, the quantum yields of anthracene within MIPs, and the fluorescence of MlPs were measured. The rebinding capacity of the MIPs was about 1 mumol/g or roughly seven times binding rate of non-imprinted polymers. The MIP fluorescence emission at 404 nm was measured for thicknesses ranging from 100 to 2000 mum containing templated anthracene concentrations ranging from 60 to 600 ppm for excitation at 358 nm. The emission agreed with model predictions within 15%. This sensing system could only distinguish anthracene down to 15 ppm due to fluorescence from the polymer matrix. To make a fluorescence-based MIP sensor that is capable of detecting one part per billion analyte concentration with a 200 mum thick MIP film, our model suggests that imprinted polymers would need to have an absorption coefficient less than 0.001 cm(-1), or have a quantum yield 10(5) times lower than that of the analyte at the detection wavelength.

  • 7. Chen, Y. C.
    et al.
    Wang, Z. M.
    Yan, Mingdi
    Department of Chemistry, Portland State University.
    Prahl, S. A.
    Fluorescence anisotropy studies of molecularly imprinted polymers2006In: Luminescence (Chichester, England Print), ISSN 1522-7235, E-ISSN 1522-7243, Vol. 21, no 1, p. 7-14Article in journal (Refereed)
    Abstract [en]

    A molecularly imprinted polymer (MIP) is a biomimetic material that can be used as a biochemical sensing element. We studied the steady-state and time-resolved fluorescence and fluorescence anisotropy of anthracene-imprinted polyurethane. We compared MIPs with imprinted analytes present, MIPs with the imprinted analytes extracted, MIPs with rebound analytes, non-imprinted control polymers (non-MIPs) and non-MIPs bound with analytes to understand MIP’s binding behaviour. MIPs and non-MIPs had similar steady-state fluorescence anisotropy in the range 0.11-0.24. Anthracene rebound in MIPs and non-MIPs had a fluorescence lifetime of tau = 0.64 ns and a rotational correlation time of 0, = 1.2-1.5 ns, both of which were shorter than that of MIPs with imprinted analytes present (tau = 2.03 ns and phi(F) = 2.7 ns). The steady-state anisotropy of polymer solutions increased exponentially with polymerization time and might be used to characterize the polymerization extent in situ.

  • 8. Chen, Y. C.
    et al.
    Wang, Z. M.
    Yan, Mingdi
    Portland State University.
    Prahl, S. A.
    Steady-state fluorescence anisotropy studies of molecularly imprinted polymer sensors2004In: MOLECULARLY IMPRINTED MATERIALS-2003 / [ed] Kofinas, P; Sellergren, B; Roberts, MJ, Materials Research Society, 2004, Vol. 787, p. 35-39Conference paper (Refereed)
    Abstract [en]

    Molecularly imprinted polymers (MIPs) are used as recognition elements in biochemical sensors. In a fluorescence-based MIP sensor system, it can be difficult to distinguish the analyte fluorescence from the fluorescence of the polymer itself. We studied steady-state fluorescence anisotropy of anthracene imprinted in a polymer (polyurethane) matrix. Vertically polarized excitation light was incident on MIP films coated on silicon wafers; vertically and horizontally polarized emission was measured. We compared the fluorescence anisotropy of MIPs with imprinted molecules, MIPs with the imprinted molecules extracted, MIPs with rebound molecules, and nonimprinted control polymers. It is shown that differences in fluorescence anisotropy between the polymers and imprinted fluorescent molecules may provide a means to discriminate the fluorescence of analyte from that of the background polymer.

  • 9.
    Deng, Lingquan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Norberg, Oscar
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Uppalapati, Suji
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Stereoselective synthesis of light-activatable perfluorophenylazide-conjugated carbohydrates for glycoarray fabrication and evaluation of structural effects on protein binding by SPR imaging2011In: Organic and biomolecular chemistry, ISSN 1477-0520, E-ISSN 1477-0539, Vol. 9, no 9, p. 3188-3198Article in journal (Refereed)
    Abstract [en]

    A series of light-activatable perfluorophenylazide (PFPA)-conjugated carbohydrate structures have been synthesized and applied to glycoarray fabrication. The glycoconjugates were structurally varied with respect to anomeric attachment, S-, and O-linked carbohydrates, respectively, as well as linker structure and length. Efficient stereoselective synthetic routes were developed, leading to the formation of the PFPA-conjugated structures in good yields over few steps. The use of glycosyl thiols as donors proved especially efficient and provided the final compounds in up to 70% total yield with high anomeric purities. PFPA-based photochemistry was subsequently used to generate carbohydrate arrays on a polymeric surface, and surface plasmon resonance imaging (SPRi) was applied for evaluation of carbohydrate-protein interactions using the plant lectin Concanavalin A (Con A) as a probe. The results indicate better performance and equal efficiency of S-and O-linked structures with intermediate linker length.

  • 10.
    Deng, Lingquan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Wang, Xin
    Uppalapati, Suji
    Norberg, Oscar
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Dong, Hai
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Joliton, Adrien
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Stereocontrolled 1-S-glycosylation and comparative binding studies of photoprobe-thiosaccharide conjugates with their O-linked analogs2013In: Pure and Applied Chemistry, ISSN 0033-4545, E-ISSN 1365-3075, Vol. 85, no 9, p. 1789-1801Article in journal (Refereed)
    Abstract [en]

    The use of thioglycosides and other glycan derivatives with anomeric sulfur linkages is gaining increasing interest, both in synthesis and in various biological contexts. Herein, we demonstrate the occurrence and circumvention of anomerization during 1-S-glycosylation reactions, and present highly efficient and stereocontrolled syntheses of a series of photoprobe-thiosaccharide conjugates. Mutarotation of glycosyl thiols proved to be the origin of the anomeric mixtures formed, and kinetic effects could be used to circumvent anomerization. The synthesized carbohydrate conjugates were then evaluated by both solution- and solid-phase-based techniques. Both binding results showed that the S-linked glycosides interact with their cognate lectins comparably to the corresponding O-analogs in the present cases, thus demonstrating the reliability of the solid-support platform built upon our photo-initiated carbohydrate immobilization method for probing protein bindings, and showing the potential of combining these two means for studying carbohydrate-protein inter-actions.

  • 11. Graupner, R K
    et al.
    Yan, Mingdi
    Department of Chemistry, Portland State University.
    Theoretical model for photochemical or thermally activated immobilization of macromolecules2004In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 20, no 20, p. 8675-8680Article in journal (Refereed)
    Abstract [en]

    The covalent immobilization of macromolecules on surfaces and within 3-dimensional networks is quantitatively described using a model based on Poisson statistics. This model determines the immobilized density or layer thickness as a function of molecular weight of the macromolecule or radiant exposure prior to and following the surface deposition of the macromolecule. Measurements of immobilized layer thickness provide first-order rate constants for decomposition of the surface-bound linker molecules and an estimate of the surface-bound linker density. The model predicts the relative density of immunocomplexed antibodies as a function of the irradiation time used to immobilize antigens. By providing the average number of bonds to the immobilized molecule, the model enables studies of the effect of multiple bonds on the activity of biomolecules. Experimental data by the authors and from the literature validate the model.

  • 12.
    Hao, Nanjing
    et al.
    Department of Chemistry, University of Massachusetts, USA.
    Neranon, Kitjanit
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. Department of Chemistry, University of Massachusetts, USA.
    Glyconanomaterials for biosensing applications2016In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 76, no 15, p. 113-130Article in journal (Refereed)
    Abstract [en]

    Nanomaterials constitute a class of structures that have unique physiochemical properties and are excellent scaffolds for presenting carbohydrates, important biomolecules that mediate a wide variety of important biological events. The fabrication of carbohydrate-presenting nanomaterials, glyconanomaterials, is of high interest and utility, combining the features of nanoscale objects with biomolecular recognition. The structures can also produce strong multivalent effects, where the nanomaterial scaffold greatly enhances the relatively weak affinities of single carbohydrate ligands to the corresponding receptors, and effectively amplifies the carbohydrate-mediated interactions. Glyconanomaterials are thus an appealing platform for biosensing applications. In this review, we discuss the chemistry for conjugation of carbohydrates to nanomaterials, summarize strategies, and tabulate examples of applying glyconanomaterials in in vitro and in vivo sensing applications of proteins, microbes, and cells. The limitations and future perspectives of these emerging glyconanomaterials sensing systems are furthermore discussed.

  • 13. Harnish, B.
    et al.
    Robinson, J. T.
    Pei, Zhichao
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    UV-cross-linked poly(vinylpyridine) thin films as reversibly responsive surfaces2005In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 17, no 16, p. 4092-4096Article in journal (Refereed)
    Abstract [en]

    We report that UV-cross-linked poly(4-vinylpyridine) (P4VP) films acted as reversibly responsive coatings that controlled surface wettability and swelling toward external stimuli: solvent and pH. The polymer films were prepared simply by spin-coating a solution of P4VP followed by UV irradiation. These cross-linked films, when treated with chloroform, showed similar to 31% increase in film thickness whereas films extracted with methylene chloride or n-butanol exhibited a slight decrease. The increase in film thickness was due to the protonation of pyridyl groups by hydrogen chloride resulting from the photodegeneration of chloroform. The film expanded to minimize repulsion around the charged centers. This hypothesis was further confirmed by exposing the cross-linked film to hydrogen chloride vapor. The film expanded similar to 37% whereas no thickness increase was observed for films exposed to ammonia or methanol vapors. The extent of swelling was monitored in situ using a quartz crystal microbalance sensor. Large oscillation frequency shifts were detected when the UV-cross-linked P4VP film was exposed to acidic buffer solutions. The changes were rapid, and the effect was reversible.

  • 14. Kamra, Tripta
    et al.
    Xu, Changgang
    Montelius, Lars
    Schnadt, Joachim
    Wijesundera, Samurdhi A.
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. University of Massachusetts Lowell, United States.
    Ye, Lei
    Photoconjugation of Molecularly Imprinted Polymer Nanoparticles for Surface-Enhanced Raman Detection of Propranolol2015In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 7, no 49, p. 27479-27485Article in journal (Refereed)
    Abstract [en]

    We report a simple and versatile method to covalently immobilize molecularly imprinted polymer (MIP) nanoparticles on a Raman active substrate (Klarite) using a disulfide-derivatized perfluorophenylazide (PFPA-disulfide). Gold-coated Klarite was functionalized with PFPA-disulfide via a gold sulfur bond. Upon light radiation, the available azido groups were converted to highly reactive singlet perfluorophenyl nitrene that undergoes a CH insertion reaction and form covalent bonds with the MIP nanoparticles. The resulting surfaces were characterized using scanning electron microscopy and surface enhanced Raman spectroscopy to study the morphology and template affinity of the surfaces, respectively. The Raman measurements clearly show a dose-responsive signal when propranolol binds to the MIP surface. Because the MIP particles were covalently attached to the Raman active substrate, the sensing surface was stable and could be reused after regeneration in acetic acid solution. The MIP-based Raman sensor was used successfully to detect propranolol in urine samples (7.7 X 10(-4) M). Our results show that the high selectivity of MLPs and the fingerprint Raman identification can be integrated into a compact sensing unit using high-efficiency photoconjugation. Thus, the method proposed is reliable, efficient and fast for fabricating label-free chemical sensors.

  • 15.
    Knudsen, Daniel
    et al.
    Portland State Univ, Dept Chem, Portland, OR 97207 USA .
    Harnish, Bernadette
    Toth, Ramona
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Creating Microstructures on Silicon Wafers Using UV-Crosslinked Polystyrene Thin Films2009In: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 49, p. 945-948Article in journal (Refereed)
    Abstract [en]

    We report that UV-crosslinked polystyrene (PS) thin films can be used as an inexpensive wet chemical etch resist to create microstructures on silicon wafers. When spin-coated PS films were irradiated, the polymer undergoes UV-induced crosslinking. Patterned PS films were successfully used as the protective layer withstanding chemical etching with the buffered HF solution. Removal of the polymer films by sonicating in water generated microstructures in silicon wafers. This simple and environmentally friendly procedure employs inexpensive commodity polymer and eliminates the use of organic solvents and harsh conditions in the subsequent development process. POLYM. ENG. SCI., 49:945-948, 2009. (C) 2009 Society of Plastics Engineers

  • 16.
    Kong, Na
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Joen, Seaho
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Covalent Functionalization of Buckminsterfullerene with Perfluorophenyl Azide by Microwave Irradiation, Photochemical or Thermal ActivationManuscript (preprint) (Other academic)
  • 17.
    Kong, Na
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Park, JaeHyeung
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Carbohydrate Functionalization of Few-Layer Graphene through Microwave-Assisted Reaction of Perfluorophenyl AzideManuscript (preprint) (Other academic)
  • 18.
    Kong, Na
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Functionalization of carbon nanomaterials with perfluorophenyl azides and their application in biorecognition2014In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 247Article in journal (Other academic)
  • 19.
    Kong, Na
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Shimpi, Manishkumar R.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Park, Jae Hyeung
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Carbohydrate conjugation through microwave-assisted functionalization of single-walled carbon nanotubes using perfluorophenyl azides2015In: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 405, p. 33-38Article in journal (Refereed)
    Abstract [en]

    Carbohydrate-functionalized single-walled carbon nanotubes (SWNTs) were synthesized using microwave-assisted reaction of perfluorophenyl azide with the nanotubes. The results showed that microwave radiation provides a rapid and effective means to covalently attach carbohydrates to SWNTs, producing carbohydrate-SWNT conjugates for biorecognition. The carbohydrate-functionalized SWNTs were furthermore shown to interact specifically with cognate carbohydrate-specific proteins (lectins), resulting in predicted recognition patterns. The carbohydrate-presenting SWNTs constitute a new platform for sensitive protein-or cell recognition, which pave the way for glycoconjugated carbon nanomaterials in biorecognition applications.

  • 20.
    Kong, Na
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry.
    Shimpi, Manishkumar R.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry.
    Park, Jaehyeung
    Univ Massachusetts, Dept Chem, Lowell, MA 01854 USA..
    Ramström, Olof
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Yan, Mingdi
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry.
    Carbohydrate conjugation through microwave-assisted functionalization of single-walled carbon nanotubes using perfluorophenyl azides (vol 405, pg 33, 2015)2015In: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 412, p. 80-80Article in journal (Refereed)
  • 21.
    Kong, Na
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Shimpi, Manishkumar
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Functionalization of carbohydrate-presenting single-walled carbon nanotubes using microwave-assisted phenylnitrene addition and their biorecognition applications2013In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 245Article in journal (Other academic)
  • 22.
    Kong, Na
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Xie, Sheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Zhou, Juan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Menendez, Margarita
    Solis, Dolores
    Park, JaeHyeung
    Proietti, Giampiero
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. University of Massachusetts Lowell, United States.
    Catalyst-Free Cycloaddition Reaction for the Synthesis of Glyconanoparticles2016In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 8, no 41, p. 28136-28142Article in journal (Refereed)
    Abstract [en]

    A new conjugation method for the immobilization of carbohydrates on nanomaterials was demonstrated simply by mixing perfluorophenyl azide-functionalized silica nanoparticles (SNPs), an amine-derivatized carbohydrate, and phenylacetaldehyde under ambient conditions without any catalyst. The density of carbohydrates on the glyconanoparticles was determined using the quantitative F-19 NMR (F-19 qNMR) technique; for example, the density of D-mannose (Man) on Man-SNPs was 2.5 +/- 0.2 x 10(-16) nmol/nm(2). The glyconanoparticles retained their binding affinity and selectivity toward cognate lectins. The apparent dissociation constant of the glyconanoparticles was measured by a fluorescence competition assay, where the binding affinity of Man-SNPs was almost 4 orders of magnitude higher than that of Man with concanavalin A. Moreover, even with a ligand density of 2.6 times lower than Man-SNPs synthesized by the copper catalyzed azide-alkyne cycloaddition, the binding affinity of Man-SNPs prepared by the current method was more than 4 times higher.

  • 23.
    Kong, Na
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Zhou, Juan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Park, JaeHyeung
    University of Massachusetts, United States .
    Xie, Sheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. University of Massachusetts, United States .
    Metal-Free Carbohydrate Immobilization on Nanoparticles Using Perfluorophenyl Azide-Based Azide-Aldehyde-Amine CycloadditionManuscript (preprint) (Other academic)
  • 24.
    Kong, Na
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Zhou, Juan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Park, JaeHyeung
    University of Massachusetts, United States .
    Xie, Sheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. University of Massachusetts, United States .
    Quantitative Fluorine NMR To Determine Carbohydrate Density on Glyconanomaterials Synthesized from Perfluorophenyl Azide-Functionalized Silica Nanoparticles by Click Reaction2015In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 87, no 18, p. 9451-9458Article in journal (Refereed)
    Abstract [en]

    A quantitative fluorine NMR (F-19 qNMR) method was developed to determine the carbohydrate density on glyconanomaterials. Mannose (Man)- and galactose (Gal)-conjugated silica nanoparticles (SNPs) were synthesized from perfluorophenyl azide (PFPA)-functionalized SNPs and propargylated Man or Gal by copper-catalyzed azide-alkyne cycloaddition (click reaction). After treating PFPA-SNPs or Man-SNPs with hydrofluoric acid followed by lyophilization, the remaining residues were directly subjected to F-19 NMR analysis. The density of PFPA on PFPA-SNP was determined to be 7.7 +/- 0.2 x 10(-16) nmol/nm(2) and Man on Man-SNP to be 6.4 +/- 0.2 x 10(-16) nmol/nm(2) giving a yield of similar to 83% for the click coupling reaction. The apparent dissociation constant (K-d) of Man-SNPs with fluorescein isothiocyanate(FITC)-concanavalin A (Con A) was determined using a fluorescence competition assay to be 0.289 +/- 0.003 mu M, which represents more than 3 orders of magnitude affinity increase compared to free Man with Con A.

  • 25. Kubo, Takuya
    et al.
    Wang, Xin
    Tong, Qi
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Polymer-based photocoupling agent for the efficient immobilization of nanomaterials and small molecules2011In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 27, no 15, p. 9372-9378Article in journal (Refereed)
    Abstract [en]

    A highly efficient photocoupling agent, based on perfluorophenylazide (PFPA)-conjugated polyallylamine (PAAm), was developed for the efficient immobilization of polymers, nanoparticles, graphene, and small molecules. The conjugate, PAAm–PFPA, was synthesized, and the percentage of the photoactive moiety, PFPA, can be controlled by the ratio of the two components in the synthesis. By treating epoxy-functionalized wafers with PAAm–PFPA, photoactive surfaces were generated. Compared with the PFPA surface, these polymer-based photocoupling matrix resulted in significantly enhanced immobilization efficiencies, especially for nanomaterials and small molecules. Thus, polystyrene nanoparticles (PS NPs) and alkyl-functionalized silica nanoparticles (SNPs) were successfully immobilized on the PAAm–PFPA surface, resulting in a high material density. Graphene flakes patterned on the PAAm–PFPA surface showed improved feature resolution in addition to a higher material density compared to that of flakes immobilized on the PFPA surface. Furthermore, 2-O-α-d-mannopyranosyl-d-mannopyranose (Man2) immobilized on the PAAm–PFPA surface exhibited significantly enhanced signals when treated with lectin concanavalin A (Con A).

  • 26. Liu, Li
    et al.
    Engelhard, Mark H.
    Yan, Mingdi
    Portland State University.
    Surface and interface control on photochemically initiated immobilization2006In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 128, no 43, p. 14067-14072Article in journal (Refereed)
    Abstract [en]

    Surface and interface properties are important in controlling the yield and efficiency of the photochemically initiated immobilization. Using a silane-functionalized perfluorophenyl azide (PFPA-silane) as the photoactive cross-linker, the immobilization of polymers was studied by adjusting the density of the surface azido groups. Dilution of the photolinker resulted in a gradual decrease in the density of surface azido groups as well as the thickness of the immobilized film. When a nonphotoactive silane was added to PFPA-silane, the film thickness decreased more rapidly, suggesting that the additive competed with PFPA-silane and effectively reduced the density of the surface azido groups. The effect of surface topography was studied by adding a nonphotoactive silane with either a shorter (n-propyltrimethoxysilane (PTMS)) or a longer spacer (n-octadecyltrimethoxysilane (ODTMS)). In most cases the long chain ODTMS shielded the surface azido groups, resulting in a more rapid decrease in film thickness as compared to PTMS treated under the same conditions. As the density of the surface azido groups decreased, the immobilized polymer changed from smooth films to patched structures and, eventually, single polymer molecules.

  • 27. Liu, Li
    et al.
    Yan, Mingdi
    Portland State University.
    A general approach to the covalent immobilization of single polymers2006In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 45, no 37, p. 6207-6210Article in journal (Refereed)
    Abstract [en]

    Stuck fast: The covalent immobilization of polymeric single molecules is achieved by the photochemically induced C-H/N-H insertion reaction of perfluorophenylazides (see picture). When the concentration of the surface azido groups is decreased, isolated polymeric single molecules are observed. This technique is especially suited for materials that do not possess functional groups and are difficult to be immobilized by other means. (Chemical Equation Presented).

  • 28. Liu, Li-Hong
    et al.
    Dietsch, Herve
    Schurtenberger, Peter
    Yan, Mingdi
    Department of Chemistry, Portland State University.
    Photoinitiated Coupling of Unmodified Monosaccharides to Iron Oxide Nanoparticles for Sensing Proteins and Bacteria2009In: Bioconjugate chemistry, ISSN 1043-1802, E-ISSN 1520-4812, Vol. 20, no 7, p. 1349-1355Article in journal (Refereed)
    Abstract [en]

    We report a versatile approach for the immobilization of unmodified monosaccharides onto iron oxide nanoparticles. Covalent coupling of the carbohydrate onto iron oxide nanoparticle surfaces was accomplished by the CH insertion reaction of photochemically activated phosphate-functionalized perfluorophenylazides (PFPAs), and the resulting glyconanoparticles were characterized by IR, TGA, and TEM. The surface-bound D-mannose showed the recognition ability toward Concanavalin A and Escherichia coli strain ORN178 that possesses mannose-specific receptor sites. Owing to the simplicity and versatility of the technique, together with the magnetic property of iron oxide nanoparticles, the methodology developed in this study serves as a general approach for the preparation of magnetic glyconanoparticles to be used in clinical diagnosis, sensing, and decontamination.

  • 29. Liu, Li-Hong
    et al.
    Lerner, Michael M.
    Yan, Mingdi
    Portland State University.
    Derivitization of Pristine Graphene with Well-Defined Chemical Functionalities2010In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 10, no 9, p. 3754-3756Article in journal (Refereed)
    Abstract [en]

    Covalent functionalization of pristine graphene poses considerable challenges due to the lack of reactive functional groups. Herein, we report a simple and general method to covalently functionalize pristine graphene with well-defined chemical functionalities. It is a solution-based process where solvent-exfoliated graphene was treated with perfluorophenylazide (PFPA) by photochemical or thermal activation. Graphene with well-defined functionalities was synthesized, and the resulting materials were soluble in organic solvents or water depending on the nature of the functional group on PFPA.

  • 30. Liu, Li-Hong
    et al.
    Nandamuri, Gopichand
    Solanki, Raj
    Yan, Mingdi
    Portland State University.
    Electrical Properties of Covalently Immobilized Single-Layer Graphene Devices2011In: Journal of Nanoscience and Nanotechnology, ISSN 1533-4880, E-ISSN 1533-4899, Vol. 11, no 2, p. 1288-1292Article in journal (Refereed)
    Abstract [en]

    Arrays of covalently immobilized and aligned graphene ribbons have been successfully prepared on silicon wafers. The effect of covalent modification on the electrical properties of the single-layer graphene was investigated. The effective electron field mobility of the constructed FETs, measured at 2700 cm(2)V(-1)s(-1), was higher than that for graphene film directly deposited on SiO(2), possibly due to lower phonon scattering from the substrate surface, implying that the field effect mobilities may be enhanced with proper choice of substrates. The contact resistance between Cr electrodes and the single-layer graphene ribbon was determined to be 1.62 k Omega from the TLM structures.

  • 31. Liu, Li-Hong
    et al.
    Yan, Mingdi
    Portland State University.
    Functionalization of pristine graphene with perfluorophenyl azides2011In: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 21, no 10, p. 3273-3276Article in journal (Refereed)
    Abstract [en]

    In this article, we highlight the recent work on the covalent functionalization of pristine graphene with perfluorophenyl azides (PFPAs). Three approaches were developed where PFPAs were employed to derivatize pristine graphene with well-defined functional groups, to fabricate graphene films and ribbons, and to generate patterned graphene structures by photolithography.

  • 32. Liu, Li-Hong
    et al.
    Yan, Mingdi
    Portland State University.
    Perfluorophenyl Azides: New Applications in Surface Functionalization and Nanomaterial Synthesis2010In: Accounts of Chemical Research, ISSN 0001-4842, E-ISSN 1520-4898, Vol. 43, no 11, p. 1434-1443Article, review/survey (Refereed)
    Abstract [en]

    A major challenge in materials science is the ongoing search for coupling agents that are readily synthesized, capable of versatile chemistry, able to easily functionalize materials and surfaces, and efficient in covalently linking organic and inorganic entities. A decade ago, we began a research program investigating perfluorophenylazides (PFPA) as the coupling agents in surface functionalization and nanomaterial synthesis. The p-substituted PFPAs are attractive heterobifunctional coupling agents because of their two distinct and synthetically distinguishable reactive centers: (i) the fluorinated phenylazide, which is capable of forming stable covalent adducts, and (ii) the functional group R, which can be tailored through synthesis. Two approaches have been undertaken for material synthesis and surface functionalization. The first method involves synthesizing PFPA bearing the first molecule or material with a functional linker R and then attaching the resulting PFPA to the second material by activating the azido group. In the second approach, the material surface is first functionalized with PFPA via functional center R, and coupling of the second molecule or material is achieved with the surface azido groups. In this Account, we review the design and protocols of the two approaches, providing examples in which PFPA derivatives were successfully used in material surface functionalization, ligand conjugation, and the synthesis of hybrid nanomaterials. The methods developed have proved to be general and versatile, and they are applicable to a wide range of materials (especially those that lack reactive functional groups or are difficult to derivatize) and to various substrates of polymers, oxides, carbon materials, and metal films. The coupling chemistry can be initiated by light, heat, and electrons. Patterned structures can be generated by selectively activating the areas of interest. Furthermore, the process is easy to perform, and light activation occurs in minutes, greatly facilitating the efficiency of the reaction. PFPAs indeed demonstrate many benefits as versatile surface coupling agents and offer opportunities for further exploration.

  • 33. Liu, Li-Hong
    et al.
    Yan, Mingdi
    Portland State University.
    Simple Method for the Covalent Immobilization of Graphene2009In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 9, no 9, p. 3375-3378Article in journal (Refereed)
    Abstract [en]

    We present a simple and efficient method to immobilize graphene on silicon wafers using perfluorophenylazide (PFPA) as the coupling agent. Graphene sheets were covalently attached to PFPA-functionalized wafer surface by a simple heat treatment under ambient conditions. The formation of single and multiple layers of graphene were confirmed by Raman spectroscopy and optical and atomic force microscopy. Evidence of covalent bond formation between graphene and PFPA decorated silicon wafer was given by X-ray photoelectron spectroscopy and sonication treatment.

  • 34. Liu, Li-Hong
    et al.
    Zorn, Gilad
    Castner, David G.
    Solanki, Raj
    Lerner, Michael M.
    Yan, Mingdi
    Portland State University.
    A simple and scalable route to wafer-size patterned graphene2010In: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 20, no 24, p. 5041-5046Article in journal (Refereed)
    Abstract [en]

    Producing large-scale graphene films with controllable patterns is an essential component of graphene-based nanodevice fabrication. Current methods of graphene pattern preparation involve either high cost, low throughput patterning processes or sophisticated instruments, hindering their large-scale fabrication and practical applications. We report a simple, effective, and reproducible approach for patterning graphene films with controllable feature sizes and shapes. The patterns were generated using a versatile photocoupling chemistry. Features from micrometres to centimetres were fabricated using a conventional photolithography process. This method is simple, general, and applicable to a wide range of substrates including silicon wafers, glass slides, and metal films.

  • 35. Liu, Wei
    et al.
    Chen, Yi
    Yan, Mingdi
    Portland State University.
    Surface plasmon resonance imaging of limited glycoprotein samples2008In: The Analyst, ISSN 0003-2654, E-ISSN 1364-5528, Vol. 133, no 9, p. 1268-1273Article in journal (Refereed)
    Abstract [en]

    A surface plasmon resonance imaging method has been developed for high throughput recognition and determination of low level glycoproteins with limited sample volume at least down to 50 nL. Chicken ovalbumin and immunoglobulin G were chosen as model compounds while bovine serum albumin and lysozyme were used as control. Each protein, at a concentration of 0.0080-1.0 mg mL(-1), was printed on one gold sensing film, and the films were simultaneously reacted with a probe solution and viewed using a laboratory-built surface plasmon resonance imaging system. The imaging signals were dependent on the concentration and the type of analyte, with a limit of detection down to at least 0.5 ng. The glycoproteins dotted at either 1.0 mg mL(-1) or 0.010 mg mL(-1) were easily differentiated from the non-glycoproteins by reaction with 200 nM concanavalin A (con A), giving a limit of recognition down also to 0.5 ng glycoprotein. This imaging method was hence considered a new tool for analyzing glycoproteins.

  • 36.
    Neranon, Kitjanit
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Hao, Nanjing
    University of Massachusetts, United States..
    Chen, Xuan
    University of Massachusetts, United States..
    Manuguri, Sesha
    University of Auckland, Auckland.
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ciprofloxacin-presenting Liposomes for Enhanced Antibacterial ActivityManuscript (preprint) (Other academic)
  • 37.
    Norberg, Oscar
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Fauquet, Germain
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Saur, Ann-Kathrin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Aastrup, Teodor
    Attana AB.
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Synthesis and Binding Affinity Analysis of α1-2- and α1-6-O/S-linked Dimannosides for the Elucidation of Sulfur in Glycosidic Bonds using Quartz Crystal Microbalance SensorsArticle in journal (Other academic)
    Abstract [en]

    Synthetic routes towards α1-2- and α1-6-linked dimannosides with S- or O-glycosidic bonds are presented. A glycosylation method was developed in which a sulfhydryl glycosyl acceptor was coupled to a 1-O-acetyl-glycosyl donor under Lewis acid catalysis. Final debenzylation of the S-linked dimannosides were accomplished through Birch reduction in high yields. The protein recognition properties of the synthesized dimannosides were then evaluated in a competition binding assay with the model lectin Con A, to investigate the effect of sulfur in the glycosidic bonds. Mannose-presenting surfaces were produced according to a previously reported Photo-Click immobilization method and the subsequent binding study was performed in an automated QCM flow through instrumentation. The recorded EC50-values correlated well to previously reported binding affinities for the O-linked dimannosides. Results were in agreement with known binding affinities, where the S-analogs displayed slightly weaker binding and a positive apparent cooperativity.

  • 38.
    Norberg, Oscar
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Lee, Irene H.
    Department of Chemistry, University of Massachusetts.
    Aastrup, Teodor
    Attana AB.
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Photogenerated lectin sensors produced by thiol-ene/yne photo-click chemistry in aqueous solution2012In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 34, no 1, p. 51-56Article in journal (Refereed)
    Abstract [en]

    The photoinitiated radical reactions between thiols and alkenes/alkynes (thiol-ene and thiol-yne chemistry) have been applied to a functionalization methodology to produce carbohydrate-presenting surfaces for analyses of biomolecular interactions. Polymer-coated quartz surfaces were functionalized with alkenes or alkynes in a straightforward photochemical procedure utilizing perfluorophenylazide (PFPA) chemistry. The alkene/alkyne surfaces were subsequently allowed to react with carbohydrate thiols in water under UV-irradiation. The reaction can be carried out in a drop of water directly on the surface without photoinitiator, and any disulfide side products were easily washed away after the functionalization process. The resulting carbohydrate-presenting surfaces were evaluated in real-time studies of protein-carbohydrate interactions using a quartz crystal microbalance (QCM) flow-through system with recurring injections of selected lectins, with intermediate regeneration steps using low pH buffer. The resulting methodology proved fast, efficient and scalable to high-throughput analysis formats, and the produced surfaces showed significant protein binding with expected selectivities of the lectins used in the study.

  • 39.
    Norberg, Oscar
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Wu, Bin
    Thota, Niranjan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Ge, Jian-Tao
    Fauquet, Germain
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Saur, Ann-Kathrin
    Aastrup, Teodor
    Dong, Hai
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry. Department of Chemistry, University of Massachusetts Lowell, 1 University Ave., MA, 01854 Lowell, USA.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry. Department of Chemistry, University of Massachusetts Lowell, 1 University Ave., MA, 01854 Lowell, USA.
    Synthesis and binding affinity analysis of alpha 1-2-and alpha 1-6-O/S-linked dimannosides for the elucidation of sulfur in glycosidic bonds using quartz crystal microbalance sensors2017In: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 452, p. 35-42Article, review/survey (Refereed)
    Abstract [en]

    The role of sulfur in glycosidic bonds has been evaluated using quartz crystal microbalance methodology. Synthetic routes towards alpha 1-2- and alpha 1-6-linked dimannosides with S-or O-glycosidic bonds have been developed, and the recognition properties assessed in competition binding assays with the cognate lectin concanavalin A. Mannose-presenting QCM sensors were produced using photoinitiated, nitrenemediated immobilization methods, and the subsequent binding study was performed in an automated flow-through instrumentation, and correlated with data from isothermal titration calorimetry. The recorded Kd-values corresponded well with reported binding affinities for the O-linked dimannosides with affinities for the alpha 1-2-linked dimannosides in the lower micromolar range. The S-linked analogs showed slightly disparate effects, where the alpha 1-6-linked analog showed weaker affinity than the O-linked dimannoside, as well as positive apparent cooperativity, whereas the alpha 1-2-analog displayed very similar binding compared to the O-linked structure. 

  • 40. Park, Jaehyeung
    et al.
    Jin, Tong
    Liu, Chao
    Li, Gonghu
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. University of Massachusetts, USA.
    Three-Dimensional Graphene-TiO2 Nanocomposite Photocatalyst Synthesized by Covalent Attachment2016In: ACS OMEGA, ISSN 2470-1343, Vol. 1, no 3, p. 351-356Article in journal (Refereed)
    Abstract [en]

    We report the synthesis of a three-dimensional graphene (3DG)-TiO2 nanocomposite by covalently attaching P25 TiO2 nanoparticles onto pristine 3DG through a perfluorophenyl azide-mediated coupling reaction. The TiO2 nanoparticles were robustly attached on the 3DG surface, with minimal particle agglomeration. In photocatalytic CO2 reduction, the 3DG-TiO2 nanocomposite demonstrated excellent activity, about 11 times higher than that of the P25 TiO2 nanoparticles. The enhanced activity can be partially attributed to the highly dispersed state of the P25 TiO2 nanoparticles on the 3DG substrate. This 3DG-based system offers a new platform for fabricating photocatalytic materials with enhanced activities.

  • 41.
    Pei, Yuxin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Yu, Hui
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Pei, Zhichao
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Theurer, Matthias
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ammer, Carolin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    André, Sabine
    Gabius, Hans-Joachim
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Photoderivatized polymer thin films at quartz crystal microbalance surfaces: Sensors for carbohydrate-protein interactions2007In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 79, no 18, p. 6897-6902Article in journal (Refereed)
    Abstract [en]

    Photoderivatized polymer-coated gold surfaces have been developed following a perfluorophenylazide-based double ligation strategy. Gold-plated quartz crystal microbalance (QCM) crystals were initially covalently functionalized with a monolayer of poly(ethylene glycol) (PEG), using photo-or thermolytic nitrene formation and insertion. The polymer surfaces were subsequently used as substrates for photoinsertion of carbohydrate-derivatized photoprobes, yielding different recognition motifs for selective protein binding. The resulting robust and biocompatible sensor surfaces were applied to a flow-through QCM instrument for monitoring lectin-carbohydrate interactions in real time. The results clearly show the predicted lectin selectivity, demonstrating the applicability of the approach.

  • 42.
    Pei, Zhichao
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Yu, Hui
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Theurer, Matthias
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Waldén, Annelie
    KTH, School of Biotechnology (BIO).
    Nilsson, Peter
    KTH, School of Biotechnology (BIO).
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Photogenerated Carbohydrate Microarrays2007In: ChemBioChem (Print), ISSN 1439-4227, E-ISSN 1439-7633, Vol. 8, no 2, p. 166-168Article in journal (Refereed)
    Abstract [en]

    Chemical Equation Presented) Sugars in a row. A new strategy for carbohydrate microarrays based on photochemical ligation of perfluorophenylazide-derivatized carbohydrates to PEO surfaces is presented. It constitutes a controllable and robust method of array fabrication, on the carbohydrate chemistry and on the surface-chemistry levels, and the resulting carbohydrate arrays can be efficiently used to reveal the recognition patterns of carbohydrate-binding proteins.

  • 43.
    Ramström, Olof
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Glyconanomaterials for Combating Bacterial Infections2015In: Chemistry A., ISSN 0947-6539, Vol. 21, no 46, p. 16310-16317Article in journal (Refereed)
    Abstract [en]

    Bacterial infections constitute an increasing problem to human health in response to build-up of resistance to present antibiotics and sluggish development of new pharmaceuticals. However, a means to address this problem is to pinpoint the drug delivery to-and into-the bacteria. This results in a high local concentration of the drug, circumventing the increasingly high doses otherwise necessary. Combined with other effectors, such as covalent attachment to carriers, rendering the drugs less degradable, and the combination with efflux inhibitors, old drugs can be revived. In this context, glyconanomaterials offer exceptional potential, since these materials can be tailored to accommodate different effectors. In this Concept article, we describe the different advantages of glyconanomaterials, and point to their potential in antibiotic "revitalization".

  • 44.
    Ramström, Olof
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Molecular imprinting - An introduction2005In: Molecularly Imprinted Materials: Science and Technology, New York: Taylor & Francis , 2005, p. 1-12Chapter in book (Refereed)
  • 45. Schmid, Daniel
    et al.
    Handge, Ulrich A.
    Gann, John P.
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Caseri, Walter
    Melt elongation of polymer nanocomposites: A method for the controlled production of dichroic films2008In: Macromolecular materials and engineering (Print), ISSN 1438-7492, E-ISSN 1439-2054, Vol. 293, no 6, p. 471-478Article in journal (Refereed)
    Abstract [en]

    A processing method based on stretching of molten polymer nanocomposites was applied to prepare dichroic films. First, dodecanethiol-capped gold particles were embedded in low density polyethylene. The resulting isotropic films were stretched in the melt under uniaxial loading using an elongational rheometer. The melt elongation technique resulted in reproducible characteristics of the optical properties and can be directly transferred to an industrial scale. The organic coating of the metal particles plays an important role in the generation of the dichroism. A reactive surface (adsorbed perfluorophenyl azide) led to strongly agglomerated particles which obviously did not lead to dichroic films.

  • 46. Sundhoro, Madanodaya
    et al.
    Jeon, Seaho
    Park, Jaehyeung
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. Univ Massachusetts Lowell, USA.
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. Univ Massachusetts Lowell, USA.
    Perfluoroaryl Azide Staudinger Reaction: A Fast and Bioorthogonal Reaction2017In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 56, no 40, p. 12117-12121Article in journal (Refereed)
    Abstract [en]

    We report a fast Staudinger reaction between perfluoroaryl azides (PFAAs) and aryl phosphines, which occurs readily under ambient conditions. A rate constant as high as 18m(-1)s(-1) was obtained between methyl 4-azido-2,3,5,6-tetrafluorobenzoate and methyl 2-(diphenylphosphanyl)benzoate in CD3CN/D2O. Furthermore, the iminophosphorane product was stable toward hydrolysis and aza-phosphonium ylide reactions. This PFAA Staudinger reaction proved to be an excellent bioothorgonal reaction. PFAA-derivatized mannosamine and galactosamine were successfully transformed into cell-surface glycans and efficiently labeled with phosphine-derivatized fluorophore-conjugated bovine serum albumin.

  • 47. Sundhoro, Madanodaya
    et al.
    Park, Jaehyeung
    Jayawardana, Kalana W.
    Chen, Xuan
    Jayawardena, H. Surangi N.
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Poly(HEMA-co-HEMA-PFPA): Synthesis and preparation of stable micelles encapsulating imaging nanoparticles2017In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 500, p. 1-8Article in journal (Refereed)
    Abstract [en]

    We report the preparation of stable micelles from random copolymers of 2-hydroxyethyl methacrylate (HEMA) and perfluorophenyl azide (PFPA)-derivatized HEMA (HEMA-PFPA). The copolymers were synthesized by RAFT polymerization at room temperature under mild conditions without affecting the azide functionality. Upon addition of water to the copolymer solution in DMSO, the random copolymers self assembled into micelles even at the percentage of HEMA-PFPA as low as 4.5%. The size of the micelles can be controlled by the molecular weight and the concentration of the copolymer, and the percentage of HEMA-PFPA in the copolymer. In addition, iron oxide nanoparticles and quantum dots were successfully encapsulated into the micelles with high encapsulation efficiency (similar to 80%). These nanoparticles, which were hydrophobic and formed agglomerates in water, became fully dispersed after encapsulating into the micelles. The micelles were stable and the size remained unchanged for at least 6 months.

  • 48. Tyagi, Anuradha
    et al.
    Wang, Xin
    Deng, Lingquan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Photogenerated carbohydrate microarrays to study carbohydrate-protein interactions using surface plasmon resonance imaging2010In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 26, no 2, p. 344-350Article in journal (Refereed)
    Abstract [en]

    A photochemical strategy to generate carbohydrate microarrays on flat sensor surfaces, and to study the protein-binding effects of these arrays by surface plasmon resonance imaging is described. The approach was validated using a panel of carbohydrate-binding proteins. The coupling agents, thiol-functionalized perfluorophenyl azides, allow the covalent attachment of underivatized carbohydrates to gold surfaces by a fast photochemical reaction. Carbohydrate microarrays composed of 3,6-di-O-(alpha-D-mannopyranosyl)-D-mannopyranose (Man3), 2-O-alpha-D-mannopyranosyl-D-mannopyranose (Man2), D-mannose (Man), D-glucose (Glc), and D-galactose (Gal) were constructed, and the binding studies were carried out in real-time using surface plasmon resonance imaging. Results showed that the immobilized carbohydrate ligands retained their binding affinities with lectins, the rank order of which was consistent with that of the free ligands in solution. The detection limit of Man3, Man2, Man, and Glc with the lectin Concanavalin A was measured to be 0.29 nM, 0.18 nM, 0.61 nM, and 3.1 nM, respectively. In addition, soybean agglutinin and Griffonia simplicifolia lectin II were tested on the array, and the results were consistent with the binding selectivity of these lectins with the carbohydrate ligands.

  • 49. Uppalapati, Suji
    et al.
    Chada, Sailaja
    Engelhard, Mark H.
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Photochemical Reactions of Poly(4-vinylphenol) Thin Films2010In: Macromolecular Chemistry and Physics, ISSN 1022-1352, E-ISSN 1521-3935, Vol. 211, no 4, p. 461-470Article in journal (Refereed)
    Abstract [en]

    The mechanism involved in the photochemical immobilization of poly (4-vinylphenol) (PVP) thin. films was investigated. The films were fabricated by a simple procedure of UV irradiation and solvent extraction. A combination of ellipsometry, IR, and high-resolution X-ray photoelectron spectroscopy (XPS) was used to provide detailed and quantitative analysis of the composition of the photochemical reaction products. Upon irradiation at 260 nm, benzyl and phenoxy radicals are generated in the polymer. In the absence of oxygen, PVP films crosslinked via the combination of the benzyl radicals or phenoxy radicals. At lower irradiation doses, the photochemical process was dominated by cross-linking of the polymer backbone via the combination of benzyl radicals. At higher exposure doses, cross-linked quinoid structures were generated, and the concentration increased with the irradiation time. No oxidation or degradation products were observed. In the presence of oxygen, additional reactions of oxidation and degradation occurred. At lower doses, oxidation at the benzyl position produced the ketone structure evidenced by the drastic increase in the 0 content in the irradiated films. As the irradiation doses increased, further oxidation at the methylene position occurred, and in addition, volatile and degradation products were also generated. This photochemical process was successfully employed to fabricate patterned PVP structures.

  • 50.
    Uppalapati, Suji
    et al.
    University of Massachusetts Lowell, United States.
    Kong, Na
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Norberg, Oscar
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. University of Massachusetts Lowell, United States.
    Ionization of covalent immobilized poly(4-vinylphenol) monolayers measured by ellipsometry, QCM and SPR2015In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 343, p. 166-171Article in journal (Refereed)
    Abstract [en]

    Covalently immobilized poly(4-vinylphenol) (PVP) monolayer films were fabricated by spin coating PVP on perfluorophenyl azide (PFPA)-functionalized surfaces followed by UV irradiation. The pH-responsive behavior of these PVP ultrathin films was evaluated by ellipsometry, quartz crystal microbalance (QCM) and surface plasmon resonance (SPR). By monitoring the responses of these films to pH in situ, the ionization constant of the monolayer thin films was obtained. The apparent plc, value of these covalently immobilized PVP monolayers, 13.4 by SPR, was 3 units higher than that of the free polymer in aqueous solution.

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