ABSTRACT
Invited for the cover of this issue are Xiao-Yu Yang and co-workers at Wuhan University of Technology, Heinrich-Heine-Universität Düsseldorf, University of the Witwatersrand, and Ben-Gurion University of the Negev. The image depicts Ti vacancies in TiO2 as powerful drivers of photo- and photo-electrocatalytic seawater splitting for hydrogen production. Read the full text of the article at 10.1002/chem.202101817.
ABSTRACT
Photodriven seawater splitting is considered to be one of the most promising techniques for sustainable hydrogen production. However, the high salinity of seawater would deactivate catalysts and consume the photogenerated carriers. Metal vacancies in metal oxide semiconductors are critical to directed electron transfer and high salinity resistance; they are thus desirable but remain a challenge. We demonstrate a facile controllable calcination approach to synthesize TiO2 nanofibers with rich Ti vacancies with excellent photo/electro performances and long-time stability in photodriven seawater splitting, including photocatalysis and photo-electrocatalysis. Experimental measurements and theoretical calculations reveal the formation of titanium vacancies, as well as unidirectional electron trap and superior H+ adsorption ability for efficient charge transfer and resistance to corrosion by seawater. Therefore, atomic-/nanoscale characteristics and mechanism have been proposed to clarify the generation of titanium vacancies and the corresponding interfacial electron transfer.
ABSTRACT
3D bioprinting technology provides programmable and customizable platforms to engineer cell-laden constructs mimicking human tissues for a wide range of biomedical applications. However, the encapsulated cells are often restricted in spreading and proliferation by dense biomaterial networks from gelation of bioinks. Herein, a cell-benign approach is reported to directly bioprint porous-structured hydrogel constructs by using an aqueous two-phase emulsion bioink. The bioink, which contains two immiscible aqueous phases of cell/gelatin methacryloyl (GelMA) mixture and poly(ethylene oxide) (PEO), is photocrosslinked to fabricate predesigned cell-laden hydrogel constructs by extrusion bioprinting or digital micromirror device-based stereolithographic bioprinting. The porous structure of the 3D-bioprinted hydrogel construct is formed by subsequently removing the PEO phase from the photocrosslinked GelMA hydrogel. Three different cell types (human hepatocellular carcinoma cells, human umbilical vein endothelial cells, and NIH/3T3 mouse embryonic fibroblasts) within the 3D-bioprinted porous hydrogel patterns show enhanced cell viability, spreading, and proliferation compared to the standard (i.e., nonporous) hydrogel constructs. The 3D bioprinting strategy is believed to provide a robust and versatile platform to engineer porous-structured tissue constructs and their models for a variety of applications in tissue engineering, regenerative medicine, drug development, and personalized therapeutics.
ABSTRACT
Polymer materials with electrically conductive properties have good applications in their respective fields because of their special properties. However, they usually exhibited poor mechanical properties and biocompatibility. In this work, we present a simple approach to prepare conductive sodium alginate (SA) and carboxymethyl chitosan (CMCS) polymer hydrogels (SA/CMCS/PPy) that can provide sufficient help for peripheral nerve regeneration. SA/CMCS hydrogel was cross-linked by calcium ions provided by the sustained release system consisting of d-glucono-δ-lactone (GDL) and superfine calcium carbonate (CaCO3), and the conductivity of the hydrogel was provided by doped with polypyrrole (PPy). Gelation time, swelling ratio, porosity and Young's modulus of the conductive SA/CMCS/PPy hydrogel were adjusted by polypyrrole content, and the conductivity of it was within 2.41 × 10-5 to 8.03 × 10-3 S cm-1. The advantages of conductive hydrogels in cell growth were verified by controlling electrical stimulation of cell experiments, and the hydrogels were also used as a filling material for the nerve conduit in animal experiments. The SA/CMCS/PPy conductive hydrogel showed good biocompatibility and repair features as a bioactive biomaterial, we expect this conductive hydrogel will have a good potential in the neural tissue engineering.
ABSTRACT
The use of a nerve conduit provides an opportunity to regulate cytokines, growth factors and neurotrophins in peripheral nerve regeneration and avoid autograft defects. We constructed a poly-D-L-lactide (PDLLA)-based nerve conduit that was modified using poly{(lactic acid)-co-[(glycolic acid)-alt-(L-lysine)]} and ß-tricalcium phosphate. The effectiveness of this bioactive PDLLA-based nerve conduit was compared to that of PDLLA-only conduit in the nerve regeneration following a 10-mm sciatic nerve injury in rats. We observed the nerve morphology in the early period of regeneration, 35 days post injury, using hematoxylin-eosin and methylene blue staining. Compared with the PDLLA conduit, the nerve fibers in the PDLLA-based bioactive nerve conduit were thicker and more regular in size. Muscle fibers in the soleus muscle had greater diameters in the PDLLA bioactive group than in the PDLLA only group. The PDLLA-based bioactive nerve conduit is a promising strategy for repair after sciatic nerve injury.
ABSTRACT
OBJECTIVE: To investigate the effects of matrine on proliferation and telomerase activity of colon cancer SW1116 cells. METHODS: The proliferation inhibitory rate was evaluated by MTT assay. The telomerase activity was analyzed by TRAP-ELISA, and the expression of hTERT mRNA was determined by semi-quantitative RT-PCR. RESULTS: Matrine displayed strong proliferation inhibitory effect in a dose-and-time-dependent manner against SW1116 cells. Compared with control group, the telomerase activity and the expression of hTERT mRNA decreased significantly (P < 0.05 or P < 0.01) in matrine group. CONCLUSION: Matrine can inhibit the telomerase activity by depressing the expression of hTERT in SW1116 cells and inhibiting cell proliferation.
