Pericytes enveloping the endothelium play an important role in the physiology and pathology of microvessels, especially in vessel maturation and stabilization. However, our understanding of fundamental pericyte biology is limited by the lack of a robust in vitro model system that allows researchers to evaluate the interactions among multiple cell types in perfusable blood vessels. The present work describes a microfluidic platform that can be used to investigate interactions between pericytes and endothelial cells (ECs) during the sprouting, growth, and maturation steps of neovessel formation. A mixture of ECs and pericytes was attached to the side of a pre-patterned three dimensional fibrin matrix and allowed to sprout across the matrix. The effects of intact coverage and EC maturation by the pericytes on the perfused EC network were confirmed using a confocal microscope. Compared with EC monoculture conditions, EC-pericyte co-cultured vessels showed a significant reduction in diameter, increased numbers of junctions and branches and decreased permeability. In response to biochemical factors, ECs and pericytes in the platform showed the similar features with previous reports from in vivo experiments, thus reflect various pathophysiological conditions of in vivo microvessels. Taken together, these results support the physiological relevancy of our three-dimensional microfluidic culture system but also that the system can be used to screen drug effect on EC-pericyte biology.
Although branched WO3 nanostructures have been investigated for electrochromic devices and catalytic electrodes, a detailed study on their structural evolution mechanism has rarely been carried out.
Although many photovoltaic (PV) grade semiconductors are shown to exhibit such a high STH efficiency as photoelectrodes, they are usually unstable during chemical reaction in aqueous solutions. On the other hand, metal oxide semiconductors are highly stable, but have poor optoelectronic properties that lead to a low STH efficiency in general. [4] Hence, a promising approach to a viable PEC device is to enhance the performance of these non-PV photoelectrodes by applying multiple modification strategies. [2] Among metal oxide light absorbers, TiO 2 (E g = 3.2 eV), WO 3 (E g = 2.8 eV), Fe 2 O 3 (E g = 2.0 eV), and BiVO 4 (E g = 2.4 eV) have been extensively studied for last two decades, but their STH efficiency remains still far less than the practical goal of 10%. [3,5] More importantly, their theoretical maximum efficiency calculated from the bandgap energy (E g ) is also below 10% except for Fe 2 O 3 . Iron-containing metal oxides (ferrites) are next generation photoelectrode materials of high potential because of their robustness, abundant availability as natural minerals, and most importantly, narrow band gaps (≈2.1 eV) allowing the theoretical STH efficiency above 13%. [6] Zinc ferrite (ZnFe 2 O 4 , ZFO) possesses these desirable properties as a potential photoanode, but unfortunately it shares the common intrinsic problem of ferrites-a poor charge carrier mobility resulting in the rapid recombination of photogenerated electron-hole pairs. In addition, its low absorption coefficient due to indirect bandgap requires a thick film for a full absorption of incident light, which is also unfavorable for charge transfer. [7] An effective strategy to promote charge transfer and separation in metal oxide light absorbers like ZFO is to adopt an electron transfer layer (ETL), which provides a facile electron transfer pathway while blocking hole transfer, like in Fe
Silicon nanostructures (SiNSs) can provide multifaceted bioapplications; but preserving their subhundred nm size during high‐temperature silica‐to‐silicon conversion is the major bottleneck. The SC‐SSR utilizes an interior metal‐silicide stratum space at a predetermined radial distance inside silica nanosphere to guide the magnesiothermic reduction reaction (MTR)‐mediated synthesis of hollow and porous SiNSs. In depth mechanistic study explores solid‐to‐hollow transformation encompassing predefined radial boundary through the participation of metal‐silicide species directing the in‐situ formed Si‐phase accumulation within the narrow stratum. Evolving thin‐porous Si‐shell remains well protected by the in‐situ segregated MgO emerging as a protective cast against the heat‐induced deformation and interparticle sintering. Retrieved hydrophilic SiNSs (<100 nm) can be conveniently processed in different biomedia as colloidal solutions and endocytosized inside cells as photoluminescence (PL)‐based bioimaging probes. Inside the cell, rattle‐like SiNSs encapsulated with Pd nanocrystals can function as biorthogonal nanoreactors to catalyze intracellular synthesis of probe molecules through C‐C cross coupling reaction.
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