Photoactive poly(3-hexylthiophene) nanoweb for optoelectrical stimulation to enhance neurogenesis of human stem cells

Optoelectrical manipulation has recently gained attention for cellular engineering; however, few material platforms can be used to efficiently regulate stem cell behaviors via optoelectrical stimulation. In this study, we developed nanoweb substrates composed of photoactive polymer poly(3-hexylthiophene) (P3HT) to enhance the neurogenesis of human fetal neural stem cells (hfNSCs) through photo-induced electrical stimulation. Methods: The photoactive nanoweb substrates were fabricated by self-assembled one-dimensional (1D) P3HT nanostructures (nanofibrils and nanorods). The hfNSCs cultured on the P3HT nanoweb substrates were optically stimulated with a green light (539 nm) and then differentiation of hfNSCs on the substrates with light stimulation was examined. The utility of the nanoweb substrates for optogenetic application was tested with photo-responsive hfNSCs engineered by polymer nanoparticle-mediated transfection of an engineered chimeric opsin variant (C1V1)-encoding gene. Results: The nanoweb substrates provided not only topographical stimulation for activating focal adhesion signaling of hfNSCs, but also generated optoelectrical stimulation via photochemical and charge-transfer reactions upon exposure to 539 nm wavelength light, leading to significantly enhanced neuronal differentiation of hfNSCs. The optoelectrically stimulated hfNSCs exhibited mature neuronal phenotypes with highly extended neurite formation and functional neuron-like electrophysiological features of sodium currents and action potentials. Optoelectrical stimulation with 539 nm light simultaneously activated both C1V1-modified hfNSCs and nanoweb substrates, which upregulated the expression and activation of voltage-gated ion channels in hfNSCs and further increased the effect of photoactive substrates on neuronal differentiation of hfNSCs. Conclusion: The photoactive nanoweb substrates developed in this study may serve as platforms for producing stem cell therapeutics with enhanced neurogenesis and neuromodulation via optoelectrical control of stem cells. © Ivyspring International Publisher1111sciescopu

Sub-THz characterisation of multi-walled carbon nanotube thin films using vector network analyser

A vector network analyser is used to study the electrical properties of multi-walled carbon nanotube (MWCNT) thin films deposited on a fused quartz substrate in the sub-terahertz (THz) frequency ranges of 220-325 GHz (WR3.4) and 325-500 GHz (WR2.2). The experiment is performed in free space. The complex permittivity of the MWCNT thin films is extracted using the Nicholson-Ross-Weir method. The refractive index and conductivity are then determined from the extracted permittivity. The method is validated by comparison with values obtained using THz time-domain spectroscopy

Inhibition of Notch1 induces population and suppressive activity of regulatory T cell in inflammatory arthritis

10.7150/thno.26093Theranostics8174795-480

Solidification in spray forming

Solidification in spray forming takes place in two distinct steps: typically half of the alloy latent heat is removed rapidly from the droplet spray created by gas atomization; the droplets are then constituted into a billet at deposition where the remaining liquid fraction solidifies relatively slowly. However, within the droplet spray, individual droplets have different thermal and solidification histories and depositing droplets may be solid, mushy, or liquid. Despite many studies of solidification behavior in spray forming, uncertainties and some misconceptions remain on how the solidification conditions in the spray and billet interact to give rise to the characteristic spray-formed microstructure comprising refined, polygonal/equiaxed primary grains with low levels of microsegregation. This article presents a simple numerical model for the spray-formed grain size arising from the deposition of the various droplets in the spray and combines insights provided by the model with previous investigations of the phenomena occurring during and immediately after deposition to propose a comprehensive description of the important solidification behavior during spray forming. Remelting, grain multiplication, thermal and elemental equilibration, and microstructural coarsening are proposed to play a critical role in the evolution of the spray-formed microstructure