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| 2. |
- Abdi-Jalebi, Mojtaba, et al.
(författare)
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Dedoping of Lead Halide Perovskites Incorporating Monovalent Cations
- 2018
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 12:7, s. 7301-7311
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Tidskriftsartikel (refereegranskat)abstract
- We report significant improvements in the optoelectronic properties of lead halide perovskites with the addition of monovalent ions with ionic radii close to Pb2+. We investigate the chemical distribution and electronic structure of solution processed CH3NH3PbI3 perovskite structures containing Na+, Cu+, and Ag+, which are lower valence metal ions than Pb2+ but have similar ionic radii. Synchrotron X-ray diffraction reveals a pronounced shift in the main perovskite peaks for the monovalent cation-based films, suggesting incorporation of these cations into the perovskite lattice as well as a preferential crystal growth in Ag+ containing perovskite structures. Furthermore, the synchrotron X-ray photoelectron measurements show a significant change in the valence band position for Cu- and Ag-doped films, although the perovskite bandgap remains the same, indicating a shift in the Fermi level position toward the middle of the bandgap. Such a shift infers that incorporation of these monovalent cations dedope the n-type perovskite films when formed without added cations. This dedoping effect leads to cleaner bandgaps as reflected by the lower energetic disorder in the monovalent cation-doped perovskite thin films as compared to pristine films. We also find that in contrast to Ag+ and Cu+, Na+ locates mainly at the grain boundaries and surfaces. Our theoretical calculations confirm the observed shifts in X-ray diffraction peaks and Fermi level as well as absence of intrabandgap states upon energetically favorable doping of perovskite lattice by the monovalent cations. We also model a significant change in the local structure, chemical bonding of metal-halide, and the electronic structure in the doped perovskites. In summary, our work highlights the local chemistry and influence of monovalent cation dopants on crystallization and the electronic structure in the doped perovskite thin films.
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| 3. |
- Abou-Hamad, Edy, et al.
(författare)
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Molecular dynamics and phase transition in one-dimensional crystal of C60 encapsulated inside single wall carbon nanotubes
- 2009
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Ingår i: ACS Nano. - Washington, DC 20036 USA : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 3:12, s. 3878-3883
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Tidskriftsartikel (refereegranskat)abstract
- One-dimensional crystals of 25% 13C-enriched C60 encapsulated inside highly magnetically purified SWNTs were investigated by following the temperature dependence of the 13C NMR line shapes and the relaxation rates from 300 K down to 5 K. High-resolution MAS techniques reveal that 32% of the encapsulated molecules, so-called the C60α, are blocked at room temperature and 68%, labeled C60β, are shown to reversly undergo molecular reorientational dynamics. Contrary to previous NMR studies, spin−lattice relaxation time reveals a phase transition at 100 K associated with the changes in the nature of the C60β dynamics. Above the transition, the C60β exhibits continuous rotational diffusion; below the transition, C60β executes uniaxial hindered rotations most likely along the nanotubes axis and freeze out below 25 K. The associated activation energies of these two dynamical regimes are measured to be 6 times lower than in fcc-C60, suggesting a quiet smooth orientational dependence of the interaction between C60β molecules and the inner surface of the nanotubes.
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| 4. |
- Acimovic, Srdjan, 1982, et al.
(författare)
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Antibody−antigen interaction dynamics revealed by analysis of single-molecule equilibrium fluctuations on individual plasmonic nanoparticle biosensors
- 2018
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-086X .- 1936-0851. ; 12:10, s. 9958-9965
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Tidskriftsartikel (refereegranskat)abstract
- Antibody−antigen interactions are complex events central to immune response, in vivo and in vitro diagnostics, and development of therapeutic substances. We developed an ultrastable single-molecule localized surface plasmon resonance (LSPR) sensing platform optimized for studying antibody−antigen interaction kinetics over very long time scales. The setup allowed us to perform equilibrium fluctuations analysis of the PEG/anti-PEG interaction. By time and frequency domain analysis, we demonstrate that reversible adsorption of monovalently bound anti-PEG antibodies is the dominant factor affecting the LSPR fluctuations. The results suggest that equilibrium fluctuation analysis can be an alternative to established methods for determination of interaction rates. In particular, the methodology is suited to analyze molecular systems whose properties change during the initial interaction phases, for example, due to mass transport limitations or, as demonstrated here, because the effective association rate constant varies with surface concentration of adsorbed molecules.
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| 5. |
- Afewerki, Samson, et al.
(författare)
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Combined Catalysis : A Powerful Strategy for Engineering Multifunctional Sustainable Lignin-Based Materials
- 2023
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 17:8, s. 7093-7108
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Tidskriftsartikel (refereegranskat)abstract
- The production and engineering of sustainable materials through green chemistry will have a major role in our mission of transitioning to a more sustainable society. Here, combined catalysis, which is the integration of two or more catalytic cycles or activation modes, provides innovative chemical reactions and material properties efficiently, whereas the single catalytic cycle or activation mode alone fails in promoting a successful reaction. Polyphenolic lignin with its distinctive structural functions acts as an important template to create materials with versatile properties, such as being tough, antimicrobial, self-healing, adhesive, and environmentally adaptable. Sustainable lignin-based materials are generated by merging the catalytic cycle of the quinone-catechol redox reaction with free radical polymerization or oxidative decarboxylation reaction, which explores a wide range of metallic nanoparticles and metal ions as the catalysts. In this review, we present the recent work on engineering lignin-based multifunctional materials devised through combined catalysis. Despite the fruitful employment of this concept to material design and the fact that engineering has provided multifaceted materials able to solve a broad spectrum of challenges, we envision further exploration and expansion of this important concept in material science beyond the catalytic processes mentioned above. This could be accomplished by taking inspiration from organic synthesis where this concept has been successfully developed and implemented.
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| 6. |
- Afewerki, Samson, et al.
(författare)
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Combined Catalysis for Engineering Bioinspired, Lignin-Based, Long-Lasting, Adhesive, Self-Mending, Antimicrobial Hydrogels
- 2020
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 14:12, s. 17004-17017
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Tidskriftsartikel (refereegranskat)abstract
- The engineering of multifunctional biomaterials using a facile sustainable methodology that follows the principles of green chemistry is still largely unexplored but would be very beneficial to the world. Here, the employment of catalytic reactions in combination with biomass-derived starting materials in the design of biomaterials would promote the development of eco-friendly technologies and sustainable materials. Herein, we disclose the combination of two catalytic cycles (combined catalysis) comprising oxidative decarboxylation and quinone-catechol redox catalysis for engineering lignin-based multifunctional antimicrobial hydrogels. The bioinspired design mimics the catechol chemistry employed by marine mussels in nature. The resultant multifunctional sustainable hydrogels (1) are robust and elastic, (2) have strong antimicrobial activity, (3) are adhesive to skin tissue and various other surfaces, and (4) are able to self-mend. A systematic characterization was carried out to fully elucidate and understand the facile and efficient catalytic strategy and the subsequent multifunctional materials. Electron paramagnetic resonance analysis confirmed the long-lasting quinone-catechol redox environment within the hydrogel system. Initial in vitro biocompatibility studies demonstrated the low toxicity of the hydrogels. This proof-of-concept strategy could be developed into an important technological platform for the eco-friendly, bioinspired design of other multifunctional hydrogels and their use in various biomedical and flexible electronic applications.
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| 7. |
- Agnarsson, Björn, 1977, et al.
(författare)
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Evanescent Light-Scattering Microscopy for Label-Free Interfacial Imaging: From Single Sub-100 nm Vesicles to Live Cells
- 2015
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-086X .- 1936-0851. ; 9:12, s. 11849-11862
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Tidskriftsartikel (refereegranskat)abstract
- Advancement in the understanding of biomolecular interactions has benefited greatly from the development of surface-sensitive bioanalytical sensors. To further increase their broad impact, significant efforts are presently being made to enable label-free and specific biomolecule detection with high sensitivity, allowing for quantitative interpretation and general applicability at low cost. In this work, we have addressed this challenge by developing a waveguide chip consisting of a flat silica core embedded in a symmetric organic cladding with a refractive index matching that of water. This is shown to reduce stray light (background) scattering and thereby allow for label-free detection of faint objects, such as individual sub-20 rim gold nanoparticles as well as sub-100 nm lipid vesicles. Measurements and theoretical analysis revealed that light-scattering signals originating from single surface-bound lipid vesicles enable characterization of their sizes without employing fluorescent lipids as labels. The concept is also demonstrated for label-free measurements of protein binding to and enzymatic (phospholipase A2) digestion of individual lipid vesicles, enabling an analysis of the influence on the measured kinetics of the dye-labeling of lipids required in previous assays. Further, diffraction-limited imaging of cells (platelets) binding to a silica surface showed that distinct subcellular features could be visualized and temporally resolved during attachment, activation, and spreading. Taken together, these results underscore the versatility and general applicability of the method, which due to its simplicity and compatibility with conventional microscopy setups may reach a widespread in life science and beyond.
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| 8. |
- Aliakbarinodehi, Nima, 1986, et al.
(författare)
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Interaction Kinetics of Individual mRNA-Containing Lipid Nanoparticles with an Endosomal Membrane Mimic: Dependence on pH, Protein Corona Formation, and Lipoprotein Depletion
- 2022
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-086X .- 1936-0851. ; 16:12, s. 20163-20173
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Tidskriftsartikel (refereegranskat)abstract
- Lipid nanoparticles (LNPs) have emerged as potent carriers for mRNA delivery, but several challenges remain before this approach can offer broad clinical translation of mRNA therapeutics. To improve their efficacy, a better understanding is required regarding how LNPs are trapped and processed at the anionic endosomal membrane prior to mRNA release. We used surface-sensitive fluorescence microscopy with single LNP resolution to investigate the pH dependency of the binding kinetics of ionizable lipid-containing LNPs to a supported endosomal model membrane. A sharp increase of LNP binding was observed when the pH was lowered from 6 to 5, accompanied by stepwise large-scale LNP disintegration. For LNPs preincubated in serum, protein corona formation shifted the onset of LNP binding and subsequent disintegration to lower pH, an effect that was less pronounced for lipoprotein-depleted serum. The LNP binding to the endosomal membrane mimic was observed to eventually become severely limited by suppression of the driving force for the formation of multivalent bonds during LNP attachment or, more specifically, by charge neutralization of anionic lipids in the model membrane due to their association with cationic lipids from earlier attached LNPs upon their disintegration. Cell uptake experiments demonstrated marginal differences in LNP uptake in untreated and lipoprotein-depleted serum, whereas lipoprotein-depleted serum increased mRNA-controlled protein (eGFP) production substantially. This complies with model membrane data and suggests that protein corona formation on the surface of the LNPs influences the nature of the interaction between LNPs and endosomal membranes.
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| 9. |
- Alijani, Hossein, et al.
(författare)
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Acoustomicrofluidic Synthesis of Pristine Ultrathin Ti3C2Tz MXene Nanosheets and Quantum Dots
- 2021
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Ingår i: ACS Nano. - : AMER CHEMICAL SOC. - 1936-0851 .- 1936-086X. ; 15:7, s. 12099-12108
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Tidskriftsartikel (refereegranskat)abstract
- The conversion of layered transition metal carbides and/or nitrides (MXenes) into zero-dimensional structures with thicknesses and lateral dimensions of a few nanometers allows these recently discovered materials with exceptional electronic properties to exploit the additional benefits of quantum confinement, edge effects, and large surface area. Conventional methods for the conversion of MXene nanosheets and quantum dots, however, involve extreme conditions such as high temperatures and/or harsh chemicals that, among other disadvantages, lead to significant degradation of the material as a consequence of their oxidation. Herein, we show that the large surface acceleration.on the order of 10 million gs.produced by high-frequency (10 MHz) nanometer-order electromechanical vibrations on a chipscale piezoelectric substrate is capable of efficiently nebulizing, and consequently dimensionally reducing, a suspension of multilayer Ti3C2Tz (MXene) into predominantly monolayer nanosheets and quantum dots while, importantly, preserving the material from any appreciable oxidation. As an example application, we show that the high-purity MXene quantum dots produced using this room-temperature chemical-free synthesis method exhibit superior performance as electrode materials for electrochemical sensing of hydrogen peroxide compared to the highly oxidized samples obtained through conventional hydrothermal synthesis. The ability to detect concentrations as low as 5 nM is a 10-fold improvement to the best reported performance of Ti3C2Tz MXene electrochemical sensors to date.
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| 10. |
- Alizadehgiashi, Moien, et al.
(författare)
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Multifunctional 3D-Printed Wound Dressings
- 2021
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 15:7, s. 12375-12387
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Tidskriftsartikel (refereegranskat)abstract
- Personalized wound dressings provide enhanced healing for different wound types; however multicomponent wound dressings with discretely controllable delivery of different biologically active agents are yet to be developed. Here we report 3D-printed multicomponent biocomposite hydrogel wound dressings that have been selectively loaded with small molecules, metal nanoparticles, and proteins for independently controlled release at the wound site. Hydrogel wound dressings carrying antibacterial silver nanoparticles and vascular endothelial growth factor with predetermined release profiles were utilized to study the physiological response of the wound in a mouse model. Compared to controls, the application of dressings resulted in improvement in granulation tissue formation and differential levels of vascular density, dependent on the release profile of the growth factor. Our study demonstrates the versatility of the 3D-printed hydrogel dressings that can yield varied physiological responses in vivo and can further be adapted for personalized treatment of various wound types.
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