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Li, X., Baryshnikov, G. V., Deng, C., Bao, X., Wu, B., Zhou, Y., . . . Zhu, L. (2019). A three-dimensional ratiometric sensing strategy on unimolecular fluorescence-thermally activated delayed fluorescence dual emission. Nature Communications, 10, Article ID 731.
Open this publication in new window or tab >>A three-dimensional ratiometric sensing strategy on unimolecular fluorescence-thermally activated delayed fluorescence dual emission
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2019 (English)In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 10, article id 731Article in journal (Refereed) Published
Abstract [en]

Visualized sensing through fluorescence signals is a powerful method for chemical and physical detection. However, the utilization of fluorescent molecular probes still suffers from lack of precise signal self-calibration in practical use. Here we show that fluorescence and thermally activated delayed fluorescence can be simultaneously produced at the single-molecular level. The thermally activated delayed fluorescence serves as a sensing signal with its wavelength and lifetime both altered correlating to polarity, whereas the fluorescence always remains unchanged as an internal reference. Upon the establishment of a three-dimensional working curve upon the ratiometric wavelength and photoluminescence lifetime vs. polarity, disturbance factors during a relevant sensing process can be largely minimized by such a multiple self-calibration. This strategy was further applied into a precise detection of the microenvironmental polarity variation in complex phospholipid systems, towards providing new insights for convenient and accurate diagnosis of membrane lesions.

Place, publisher, year, edition, pages
NATURE PUBLISHING GROUP, 2019
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-245138 (URN)10.1038/s41467-019-08684-2 (DOI)000458567500011 ()30760723 (PubMedID)2-s2.0-85061511851 (Scopus ID)
Note

QC 20190313

Available from: 2019-03-13 Created: 2019-03-13 Last updated: 2019-03-13Bibliographically approved
Mudedla, S. K., Natarajan Arul, M., Subramanian, V. & Ågren, H. (2019). Destabilization of amyloid fibrils on interaction with MoS2-based nanomaterials. RSC Advances, 9(3), 1613-1624
Open this publication in new window or tab >>Destabilization of amyloid fibrils on interaction with MoS2-based nanomaterials
2019 (English)In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 9, no 3, p. 1613-1624Article in journal (Refereed) Published
Abstract [en]

The present work is motivated by the established concept that the structure and energetics of biomacromolecules can be modulated by confining their dimensions in the nanoscale. In particular, here we use force-field methods to understand the stability of amyloid fibrils at nanostructured interfaces, which can be useful for the development of new therapeutics for Alzheimer's disease. We explore the binding modes and structural properties of fibrils at the interface of molybdenum disulphide nanotubes and the nanosurface using classical molecular dynamics simulations. We find that in general the MoS2 materials induces disruptions in the structure of the amyloid fibrils where the beta sheet conformation of the fibrils changes to a turned conformation, and it is large in the case of nanotubes in comparison to the nanosurfaces. The intermolecular hydrogen bonds, hydrophilic and hydrophobic contacts between the monomer peptides in the fibril are reduced due to their adsorption onto the MoS2 materials, which results in a destabilization of the fibril. The destabilization of fibril is to some extent compensated for by the van der Waals interactions between the fibril and MoS2. Overall the results indicate that MoS2-based materials can be useful in inhibiting the aggregation of smaller protofibrils to matured fibrils and to bust the already formed fibrils. Therapeutic materials should not exhibit any cross interaction with other off-targets compounds. In order to test whether the MoS2 nanomaterial has any such effect we have studied its interaction with two additional biomacromolecules, the human serum albumin and p53 protein, and we report no significant changes in the secondary structure of these biomolecules. Through molecular docking studies we also established that the drug binding ability of HSA is not altered by its surface binding to MoS2 nanosurface.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2019
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-244120 (URN)10.1039/c8ra10184a (DOI)000457292800050 ()2-s2.0-85060139369 (Scopus ID)
Note

QC 20190219

Available from: 2019-02-19 Created: 2019-02-19 Last updated: 2019-02-19Bibliographically approved
Li, X., Duan, S., Liu, H., Chen, G., Luo, Y. & Ågren, H. (2019). Mechanism for the Extremely Efficient Sensitization of Yb(3+)Luminescence in CsPbCl3 Nanocrystals. Journal of Physical Chemistry Letters, 10(3), 487-492
Open this publication in new window or tab >>Mechanism for the Extremely Efficient Sensitization of Yb(3+)Luminescence in CsPbCl3 Nanocrystals
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2019 (English)In: Journal of Physical Chemistry Letters, ISSN 1948-7185, E-ISSN 1948-7185, Vol. 10, no 3, p. 487-492Article in journal (Refereed) Published
Abstract [en]

Rare earth ion (RE3+)-doped inorganic CsPbX3 (X = Cl or Cl/Br) nanocrystals have been presented as promising materials for applications in solar-energy conversion technology. An extremely efficient sensitization of Yb3+ luminescence in CsPbCl3 nanoparticles (NCs) was very recently demonstrated where quantum cutting is responsible for the performance of photoluminescence quantum yields over 100% (T. J. Milstein, et al. Nano Letters 2018, 18, 3792). In the present work, based on the cubic phase of inorganic perovskite, we seek to obtain atom-level insight into the basic mechanisms behind these observations in order to boost the further development of RE3+-doped CsPbX3 NCs for optoelectronics. In our calculations of cubic crystal structure, we do not find any energy level formed in the middle of the band gap, which disfavors a mechanism of stepwise energy transfer from the perovskite host to two Yb3+ ions. Our work indicates that the configuration with "right-angle" Yb3+-V-Pb-Yb3+ couple is most likely to form in Yb3+-doped CsPbCl3. Associated with this "right-angle" couple, the "right-angle" Pb atom with trapped excited states would localize the photogenerated electrons and act as the energy donor in a quantum cutting process, which achieves simultaneous sensitization of two neighboring Yb3+ ions.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:kth:diva-245142 (URN)10.1021/acs.jpclett.8b03406 (DOI)000458704800026 ()30642182 (PubMedID)
Note

QC 20190313

Available from: 2019-03-13 Created: 2019-03-13 Last updated: 2019-03-13Bibliographically approved
Guanglin, K., Murugan, N. A. & Ågren, H. (2019). Mechanistic Insight into the Binding Profile of DCVJ and alpha-Synuclein Fibril Revealed by Multiscale Simulations. ACS Chemical Neuroscience, 10(1), 610-617
Open this publication in new window or tab >>Mechanistic Insight into the Binding Profile of DCVJ and alpha-Synuclein Fibril Revealed by Multiscale Simulations
2019 (English)In: ACS Chemical Neuroscience, ISSN 1948-7193, E-ISSN 1948-7193, Vol. 10, no 1, p. 610-617Article in journal (Refereed) Published
Abstract [en]

Parkinson's disease (PD) is a serious neuro-degenerative disease and is characterized by abnormal alpha-synuclein (alpha-syn) accumulation in Lewy bodies (LB) and 2 Lewy neurites (LN), which makes alpha-syn an important imaging target for PD. An imaging probe that quantifies fibrillar alpha-syn can enhance the clinical diagnosis of PD and can also be used to evaluate the efficacy of therapeutics aimed at reducing the abnormal aggregation of the alpha-syn fibril in the brain. In this paper, we study the binding profile of fibrillar alpha-syn with a fluorescent probe 4-(dicyanovinyl)julolidine (DCVJ), which is being explored for identifying alpha-syn imaging agents. A multiscale simulation workflow including molecular docking, molecular dynamics, metadynamics, and QM/MM calculations was implemented. We find that DCVJ can bind to multiple sites of alpha-syn which are located either at the surface or in the core. Free energy calculations using implicit solvent models reveal that the most favorable binding mode for DCVJ is associated with the core binding site and is further confirmed by metadyamics simulation. Besides, a dynamic binding pathway is discovered, which reveals that DCVJ binds gradually into the core of the fibril passing through several intermediate states. The conformational arrest of the dicyano vinyl group in the fibrillar environment could explain the reason behind the fibril-specific fluorescence of DCVJ. Furthermore, based on hybrid QM/MM calculations, the molecular geometry of the dicyano vinyl group is found to be environment specific which explains why DCVJ serves as a staining agent for such fibrillar-like environments. Our results could be helpful for elucidating the binding mechanism of imaging tracers with the fibrillar form of alpha-syn and explain their fibrillar-specific optical properties, a knowledge that in turn can be used to guide the design and development of compounds with higher affinity and selectivity for alpha-syn using structure-based strategies.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
Keywords
alpha-Synuclein, DCVJ, imaging agents, molecular docking, binding free energy calculations, metadynamics
National Category
Theoretical Chemistry
Identifiers
urn:nbn:se:kth:diva-243968 (URN)10.1021/acschemneuro.8b00465 (DOI)000456351300062 ()30277753 (PubMedID)2-s2.0-85055257565 (Scopus ID)
Note

QC 20190301

Available from: 2019-03-01 Created: 2019-03-01 Last updated: 2019-03-01Bibliographically approved
Pidluzhna, A., Ivaniuk, K., Stakhira, P., Hotra, Z., Chapran, M., Ulanski, J., . . . Ågren, H. (2019). Multi-channel electroluminescence of CdTe/CdS core-shell quantum dots implemented into a QLED device. Dyes and pigments, 162, 647-653
Open this publication in new window or tab >>Multi-channel electroluminescence of CdTe/CdS core-shell quantum dots implemented into a QLED device
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2019 (English)In: Dyes and pigments, ISSN 0143-7208, E-ISSN 1873-3743, Vol. 162, p. 647-653Article in journal (Refereed) Published
Abstract [en]

CdTe/CdS core-shell quantum dots were synthesized and implemented into a light emitting device resulting in multi-channel electroluminescence with a light-green emission color. The main electroluminescence band at about 530 nm corresponds to the emission by the CdTe core (type I core/shell structure), while the next emission band at 595 nm is assigned to the crossed recombination of electrons from the conduction band of the CdS shell and holes from the valence band of the CdTe core (type II core/shell structure). At the same time, the photoluminescence spectrum of the synthesized CdTe/CdS core-shell quantum dots contains only one emission band distinctive for type II structures. This behavior of CdTe/CdS core-shell quantum dots upon the electroexcitation allows the extension of the electroluminescence spectrum in the optical region in a way that is useful for lighting source applications. Such multi-channel electroluminescence can most probably also be reproduced in related core-shell systems accounting for size-confinement between the core size and shell thickness.

Place, publisher, year, edition, pages
ELSEVIER SCI LTD, 2019
Keywords
Quantum dots, Core-shell structures, Electroluminescence, Photoluminescence, QLED
National Category
Theoretical Chemistry
Identifiers
urn:nbn:se:kth:diva-243931 (URN)10.1016/j.dyepig.2018.10.074 (DOI)000456226500073 ()2-s2.0-85055979450 (Scopus ID)
Note

QC 20190313

Available from: 2019-03-13 Created: 2019-03-13 Last updated: 2019-03-13Bibliographically approved
Lu, Y., Song, H., Li, X., Ågren, H., Liu, Q., Zhang, J., . . . Xie, Y. (2019). Multiply Wrapped Porphyrin Dyes with a Phenothiazine Donor: A High Efficiency of 11.7% Achieved through a Synergetic Coadsorption and Cosensitization Approach. ACS Applied Materials and Interfaces, 11(5), 5046-5054
Open this publication in new window or tab >>Multiply Wrapped Porphyrin Dyes with a Phenothiazine Donor: A High Efficiency of 11.7% Achieved through a Synergetic Coadsorption and Cosensitization Approach
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2019 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 11, no 5, p. 5046-5054Article in journal (Refereed) Published
Abstract [en]

Photocurrent (J) and photovoltage (Vac) are two important parameters for dye-sensitized solar cells (DSSCs) to achieve high power conversion efficiencies (PCEs). Herein, we synthesize four novel porphyrin dyes, XW36 XW39, using an N-phenyl-substituted phenothiazine donor to pursue higher PCE. For XW36 and XW37, the N-phenyl group is wrapped with two ortho-alkoxy chains. In contrast, it is substituted with a para-alkoxy group in XW38 and XW39. The phenothiazine wrapping in XW36 and XW37 induces more serious distortion, which is beneficial for anti-aggregation but unfavorable for the electron transfer from donor to a porphyrin framework. Thus, individual porphyrin dyes XW36 and XW37 exhibit efficiencies of 9.05 and 9.58%, respectively, lower than those of 9.51 and 10.0% achieved for XW38 and XW39, respectively. Besides, the introduction of a methyl group into a benzoic acid acceptor unit is conducive to anti-aggregation and thus improves the V-oc and efficiencies. Therefore, higher efficiencies were achieved for XW37 and XW39, compared with XW36 and XW38, respectively. Interestingly, although the individual XW36 dye shows a lowest efficiency among the four dyes, a highest efficiency of 11.7% was obtained for XW36 on the basis of synergetic adsorption with chenodeoxycholic acid and PT-C6 because of simultaneously improved J and Voc, which may be ascribed to the lowest dye-loading amount of XW36 among all of these porphyrin dyes, with the largest vacancy area left on the TiO2 surface available for cosensitizer PT-C6, resulting in a highest J. The high efficiency of 11.7% is one of the highest efficiencies using I-/I-3(-) electrolytes in DSSCs. These results provide an effective strategy for developing efficient DSSCs by the targeted coadsorption and cosensitization of porphyrin sensitizers optimized through introducing a bis(ortho-alkoxy)-wrapped phenyl group into the phenothiazine donor and/or methyl groups into the benzoic acid acceptor unit.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
Keywords
phenothiazine, porphyrin, wrapped structure, coadsorption, cosensitization
National Category
Other Chemistry Topics
Identifiers
urn:nbn:se:kth:diva-245144 (URN)10.1021/acsami.8b19077 (DOI)000458347900036 ()30644719 (PubMedID)
Note

QC 20190313

Available from: 2019-03-13 Created: 2019-03-13 Last updated: 2019-03-13Bibliographically approved
Li, X., Duan, S., Liu, H., Chen, G., Luo, Y. & Ågren, H. (2019). On the Mechanism for the Extremely Efficient Sensitization of Yb3+ Luminescence in CsPbCl3 Nanocrystals. The Journal of Physical Chemistry Letters, 10(3), 487-492
Open this publication in new window or tab >>On the Mechanism for the Extremely Efficient Sensitization of Yb3+ Luminescence in CsPbCl3 Nanocrystals
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2019 (English)In: The Journal of Physical Chemistry Letters, Vol. 10, no 3, p. 487-492Article in journal (Refereed) Published
Abstract [en]

Rare earth ion (RE3+)-doped inorganic CsPbX3 (X = Cl or Cl/Br) nanocrystals have been presented as promising materials for applications in solar-energy conversion technology. An extremely efficient sensitization of Yb3+ luminescence in CsPbCl3 nanoparticles (NCs) was very recently demonstrated where quantum cutting is responsible for the performance of photoluminescence quantum yields over 100% (T. J. Milstein, et al. Nano Letters 2018, 18, 3792). In the present work, based on the cubic phase of inorganic perovskite, we seek to obtain atom-level insight into the basic mechanisms behind these observations in order to boost the further development of RE3+-doped CsPbX3 NCs for optoelectronics. In our calculations of cubic crystal structure, we do not find any energy level formed in the middle of the band gap, which disfavors a mechanism of stepwise energy transfer from the perovskite host to two Yb3+ ions. Our work indicates that the configuration with "right-angle" Yb3+-V-Pb-Yb3+ couple is most likely to form in Yb3+-doped CsPbCl3. Associated with this "right-angle" couple, the "right-angle" Pb atom with trapped excited states would localize the photogenerated electrons and act as the energy donor in a quantum cutting process, which achieves simultaneous sensitization of two neighboring Yb3+ ions.

National Category
Nano Technology
Identifiers
urn:nbn:se:kth:diva-246213 (URN)10.1021/acs.jpclett.8b03406 (DOI)000458704800026 ()2-s2.0-85061130625 (Scopus ID)
Note

QC 20190318

Available from: 2019-03-16 Created: 2019-03-16 Last updated: 2019-03-18Bibliographically approved
Karaush, N. N., Baryshnikov, G. V., Ågren, H. & Minaev, B. F. (2018). A theoretical study of new representatives of closed- and open-circle benzofuran and benzocyclopentadienone oligomers. New Journal of Chemistry, 42(14), 11493-11505
Open this publication in new window or tab >>A theoretical study of new representatives of closed- and open-circle benzofuran and benzocyclopentadienone oligomers
2018 (English)In: New Journal of Chemistry, ISSN 1144-0546, E-ISSN 1369-9261, Vol. 42, no 14, p. 11493-11505Article in journal (Refereed) Published
Abstract [en]

Owing to their potential use as materials for strong optical rotation, circular dichroism and circularly polarized luminescence, the structure and energetic stability of novel closed- and open-circle benzofuran and benzocyclopentadienone oligomers have been studied computationally using the DFT method. It is found that an extension of the macrocycle size (n = 10-30) for the closed-circle species leads to a gradual transformation of their structure from saddle- to helical- and then to a wing-like shape. At the same time, the smaller closed-circle representatives with n = 4 and 6 exhibit a bowl-shaped structure due to the high energy strain of their molecular structures. Application of the NICS (nucleus-independent chemical shift) criterion to the here studied open-circle benzofuran and benzocyclopentadienone species with planar linear, planar fan-shape and helical molecular topology indicates that for the planar benzofuran series the inner benzene ring is more aromatic than the outer hexagons, while the aromaticity of the outer and inner furan rings is insensitive to the molecular size variations. The replacement of the aromatic furan rings by antiaromatic cyclopentadienone fragments for the planar linear species leads to a decrease of aromaticity of the benzene rings from the edge to the center of the benzocyclopentadienone chain. On the other hand, for the planar fan-shape benzocyclopentadienone series a zigzag trend in the NICS values is observed for the benzene rings. Loss of planarity only slightly affects the aromaticity of the helical open-circle benzofuran and benzocyclopentadienone oligomers. We propose that an increase of the NICS indices for the outer and inner rings of the macromolecular helical species is due to the magnetic couplings between the superimposed benzene and furan/cyclopentadienone rings.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2018
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-232758 (URN)10.1039/c8nj00601f (DOI)000438394800034 ()2-s2.0-85049737696 (Scopus ID)
Funder
Swedish National Infrastructure for Computing (SNIC)Carl Tryggers foundation , CTS 17:514
Note

QC 20180803

Available from: 2018-08-03 Created: 2018-08-03 Last updated: 2018-08-03Bibliographically approved
Zhou, Y., Baryshnikov, G. V., Li, X., Zhu, M., Ågren, H. & Zhu, L. (2018). Anti-Kasha's Rule Emissive Switching Induced by Intermolecular H-Bonding. Chemistry of Materials, 30(21), 8008-8016
Open this publication in new window or tab >>Anti-Kasha's Rule Emissive Switching Induced by Intermolecular H-Bonding
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2018 (English)In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 30, no 21, p. 8008-8016Article in journal (Refereed) Published
Abstract [en]

The exploration of emission pathways from high-excited states in organic luminogens has recently become prosperous owing to improved possibilities to study so-called anti-Kasha's rule emission with the potential of improving the luminescent quantum efficiency. However, emission pathway switching among different high-excited states has rarely been addressed through external control. We here present a rational design and synthesis of a novel azulene-based emitter to achieve a responsive control of its anti-Kasha's rule emissive switching. The emitter initially gives rise to an S-3-to-S-0 dominant emission as indicated by our experimental and theoretical studies. On this basis, it can be toggled into an S-2-to-S-0 dominant emission upon the H-bond formation between the triformyl groups and water molecules. Such a process, which originates from the H-bonding regulated distribution of excited state energy, is accompanied by a remarkable fluorescent color conversion and a significant improvement of the fluorescent quantum yield in the azulene family. Moreover, a reversible emissive switching in doped films was observed to depend on a solid-state H-bond tuning process with moisture sensitivity. These results may provide new insight for building advanced chemical systems for visualized sensing with high distinguishability.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2018
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-240002 (URN)10.1021/acs.chemmater.8b03699 (DOI)000450696100068 ()2-s2.0-85055633460 (Scopus ID)
Funder
Carl Tryggers foundation , CTS 16:536 17:514
Note

QC 20181210

Available from: 2018-12-10 Created: 2018-12-10 Last updated: 2018-12-10Bibliographically approved
Natarajan Arul, M., Nordberg, A. & Ågren, H. (2018). Different Positron Emission Tomography Tau Tracers Bind to Multiple Binding Sites on the Tau Fibril: Insight from Computational Modeling. ACS Chemical Neuroscience, 9(7), 1757-1767
Open this publication in new window or tab >>Different Positron Emission Tomography Tau Tracers Bind to Multiple Binding Sites on the Tau Fibril: Insight from Computational Modeling
2018 (English)In: ACS Chemical Neuroscience, ISSN 1948-7193, E-ISSN 1948-7193, Vol. 9, no 7, p. 1757-1767Article in journal (Refereed) Published
Abstract [en]

Using the recently reported cryo-EM structure for the tau fibril [Fitzpatrick et al. (2017) Nature 547, 185-190], which is a potential target concerning Alzheimer's disease, we present the first molecular modeling studies on its interaction with various positron emission tomography (PET) tracers. Experimentally, based on the binding assay studies, at least three different high affinity binding sites have been reported for tracers in the tau fibril. Herein, through integrated modeling using molecular docking, molecular dynamics, and binding free energy calculations, we provide insight into the binding patterns of various tracers to the tau fibril. We suggest that there are four different high affinity binding sites available for many of the studied tracers showing varying binding affinity to different binding sites. Thus, PBB3 binds most strongly to site 4, and interestingly, this site is not a preferable site for any other tracers. For THIC5351, our data show that it strongly binds to sites 3 and 1, the former one being more preferable. We also find that MK6240 and T807 bind to site 1 specifically. The modeling data also give some insight into whether a tracer bound to a specific site can be replaced by others or not. For example, the displacement of T807 by PBB3 as reported experimentally can also be explained and attributed to the larger binding affinity of the latter compound in all binding sites. The binding free energy results explain very well the small binding affinity of THK523 compared to all the aryl quinoline moieties containing THK tracers. The ability of certain tau tracers, like FDDNP and THK523, to bind to amyloid fibrils has also been investigated. Furthermore, such off-target interaction of tau tracers with amyloid beta fibrils has been validated using a quantum mechanical fragmentation approach.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2018
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-232912 (URN)10.1021/acschemneuro.8b00093 (DOI)000439531400024 ()29630333 (PubMedID)2-s2.0-85050285842 (Scopus ID)
Note

QC 20180808

Available from: 2018-08-08 Created: 2018-08-08 Last updated: 2018-11-13Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-1763-9383

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