| 1. |
- Bansal, Akshaya, et al.
(författare)
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Quasi-Continuous Wave Near-Infrared Excitation of Upconversion Nanoparticles for Optogenetic Manipulation of C. elegans
- 2016
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Ingår i: Small. - : Wiley. - 1613-6810 .- 1613-6829. ; 12:13, s. 1732-1743
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Tidskriftsartikel (refereegranskat)abstract
- Optogenetics is an emerging powerful tool to investigate workings of the nervous system. However, the use of low tissue penetrating visible light limits its therapeutic potential. Employing deep penetrating near-infrared (NIR) light for optogenetics would be beneficial but it cannot be used directly. This issue can be tackled with upconversion nanoparticles (UCNs) acting as nanotransducers emitting at shorter wavelengths extending to the UV range upon NIR light excitation. Although attractive, implementation of such NIR-optogenetics is hindered by the low UCN emission intensity that necessitates high NIR excitation intensities, resulting in overheating issues. A novel quasi-continuous wave (quasi-CW) excitation approach is developed that significantly enhances multiphoton emissions from UCNs, and for the first time NIR light-triggered optogenetic manipulations are implemented in vitro and in C. elegans. The approach developed here enables the activation of channelrhodopsin-2 with a significantly lower excitation power and UCN concentration along with negligible phototoxicity as seen with CW excitation, paving the way for therapeutic optogenetics.
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| 2. |
- Björk, Per, et al.
(författare)
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Oligothiophene Assemblies Defined by DNA Interaction : From Single Chains to Disordered Clusters
- 2009
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Ingår i: SMALL. - : Wiley. - 1613-6810 .- 1613-6829. ; 5:1, s. 96-103
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Tidskriftsartikel (refereegranskat)abstract
- The organization of conjugated polyelectrolytes (CPEs) interacting with biomolecules sets conditions for the biodetection of biological processes and identity, through the use of optical emission from the CPE. Herein, a well-defined CPE and its binding to DNA is studied. By using dynamic light scattering and circular dichroism spectroscopy, it is shown that the CPE forms a multimolecule ensemble in aqueous solution that is more than doubled it? size when interacting with a small DNA chain, while single chains are evident in ethanol. The related changes in the fluorescence spectra upon polymer aggregation are assigned to oscillator strength redistribution between vibronic transitions in weakly coupled H-aggregates. An enhanced single-molecule spectroscopy technique that allows full control of excitation and emission light polarization is applied to combed and decorated;,DNA chains. It is found that the organization of combed CPE-lambda DNA complexes (when dry on the surface) allows considerable variation of CPE distances and direction relative to the DNA chain. By analysis of the polarization data. energy transfer between the polymer chains in individual complexes is confirmed and their sizes estimated.
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| 3. |
- Bordag, Michael, et al.
(författare)
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Shear stress measurements on InAs nanowires by AFM manipulation
- 2007
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Ingår i: Small. - Weinheim : Wiley-VCH Verlagsgesellschaft. - 1613-6810 .- 1613-6829. ; 3:8, s. 1398-1401
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Tidskriftsartikel (refereegranskat)abstract
- On an upward curve? The curvature of an elastically deformed nanowire pinned to a flat surface contains information about the maximum static friction force, and hence the shear stress, between the nanowire and the surface. Here, InAs nanowires are bent in a controlled manner using the tip of an atomic force microscope (see image). The shear stress can be obtained from a simple analysis according to the standard theory of elasticity.
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| 4. |
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| 5. |
- Cautela, J., et al.
(författare)
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Sphere–Tubule Superstructures through Supramolecular and Supracolloidal Assembly Pathways
- 2018
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Ingår i: Small. - : Wiley. - 1613-6810 .- 1613-6829. ; 14:50
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Tidskriftsartikel (refereegranskat)abstract
- While colloids have been widely employed as models for atoms and molecules, the current study proposes to extend their use as building blocks for supracolloidal frameworks. Hereby, the self-assembly between highly anisotropic supramolecular microtubules and soft spherical fluorescent microgels is explored using confocal laser scanning microscopy. The influence of the particle size and charge with respect to the catanionic tubule composition, which consists of two oppositely charged bile salt derivatives, is investigated. Under certain conditions, microgel particles are found to specifically interact with the extremities of the tubular aggregates and hierarchically self-assemble into various superstructures varying from virus-like assemblies to supracolloidal networks. The reported approach is envisioned to open new self-assembly routes toward ordered hybrid superstructures where the spherical colloids act as responsive linkers of tubular structures.
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| 6. |
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| 7. |
- Conache, Gabriela, et al.
(författare)
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Friction measurements of InAs nanowires on Silicon nitride by AFM manipulation
- 2009
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Ingår i: Small. - Weinheim, Germany : Wiley-VCH Verlagsgesellschaft. - 1613-6810 .- 1613-6829. ; 5:2, s. 203-207
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Tidskriftsartikel (refereegranskat)abstract
- A study was conducted to perform friction measurements of InAs nanowires (NW) on silicon nitride (Si 3N 4) through atomic force microscopy (AFM) manipulation. The investigations revealed the friction force per unit length for sliding and static friction over a range of nanowire diameters. It was found that there is a significant difference between the coefficients of the two sliding modes for large wires. It was also found that the difference between the two sliding modes disappears at smaller diameters and the sliding friction becomes equal with the static friction. The AFM investigations were performed on a Nanoscope IIIa Dimension 3100, using rectangular cantilevers, with a nominal spring constant of 30 N m -1. The nanowires were manipulated, using the 'Retrace Lift' mode of the AFM controller. The friction force per unit length was gathered from the local curvature of the NWs, using standard elasticity theory.
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| 8. |
- Do, Xuan Huy, et al.
(författare)
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Membrane Assemblies with Soft Protective Layers : Dense and Gel-Type Polybenzimidazole Membranes and Their Use in Vanadium Redox Flow Batteries
- 2022
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Ingår i: Small. - : Wiley. - 1613-6810 .- 1613-6829. ; 18:50
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Tidskriftsartikel (refereegranskat)abstract
- Polybenzimidazole (PBI) membranes show excellent chemical stability and low vanadium crossover in vanadium redox flow batteries (VRFBs), but their high resistance is challenging. This work introduces a concept, membrane assemblies of a highly selective 2 µm thin PBI membrane between two 60 µm thick highly conductive PBI gel membranes, which act as soft protective layers against external mechanical forces and astray carbon fibers from the electrode. The soft layers are produced by casting phosphoric acid solutions of commercial PBI powder into membranes and exchanging the absorbed acid into sulfuric acid. A conductivity of 565 mS cm−1 is achieved. A stability test indicates that gel mPBI and dense PBI-OO have higher stability than dense mPBI and dense py-PBI, and gel/PBI-OO/gel is successfully tested for 1070 cycles (ca. 1000 h) at 100 mA cm−2 in the VRFB. The initial energy efficiency (EE) for the first 50 cycles is 90.5 ± 0.2%, and after a power outage stabilized at 86.3 ± 0.5% for the following 500 cycles. The initial EE is one of the highest published so far, and the materials cost for a membrane assembly is 12.35 U.S. dollars at a production volume of 5000 m2, which makes these membranes very attractive for commercialization.
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| 9. |
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| 10. |
- Hebisch, Elke, et al.
(författare)
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Nanostraw-Assisted Cellular Injection of Fluorescent Nanodiamonds via Direct Membrane Opening
- 2021
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Ingår i: Small. - : Wiley. - 1613-6810 .- 1613-6829. ; 17:7
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Tidskriftsartikel (refereegranskat)abstract
- Due to their stable fluorescence, biocompatibility, and amenability to functionalization, fluorescent nanodiamonds (FND) are promising materials for long term cell labeling and tracking. However, transporting them to the cytosol remains a major challenge, due to low internalization efficiencies and endosomal entrapment. Here, nanostraws in combination with low voltage electroporation pulses are used to achieve direct delivery of FND to the cytosol. The nanostraw delivery leads to efficient and rapid FND transport into cells compared to when incubating cells in a FND-containing medium. Moreover, whereas all internalized FND delivered by incubation end up in lysosomes, a significantly larger proportion of nanostraw-injected FND are in the cytosol, which opens up for using FND as cellular probes. Furthermore, in order to answer the long-standing question in the field of nano-biology regarding the state of the cell membrane on hollow nanostructures, live cell stimulated emission depletion (STED) microscopy is performed to image directly the state of the membrane on nanostraws. The time-lapse STED images reveal that the cell membrane opens entirely on top of nanostraws upon application of gentle electrical pulses, which supports the hypothesis that many FND are delivered directly to the cytosol, avoiding endocytosis and lysosomal entrapment.
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