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Background Hypermethylation of gene promoters has been regarded as an epigenetic regulator for gene inactivation in the development of several diseases. In the current study, we aimed to explore how long noncoding RNA X-inactive specific transcript (lncRNA XIST) function in collagen degradation in chondrocytes of osteoarthritis (OA) after tibial plateau fracture by regulating tissue inhibitor of metalloproteinase-3 (TIMP-3) promoter methylation. Methods In silico analysis was used to screen differentially expressed lncRNAs in cartilage tissues of OA. Chondrocytes were then successfully isolated from normal and OA cartilage tissues and identified, with the expressions of lncRNA XIST and TIMP-3 examined. The methylation levels of TIMP-3 promoter were determined by MS-PCR. The binding of lncRNA XIST to DNA methyltransferase and the binding of TIMP-3 promoter to DNA methyltransferase were determined by a series of experiments, including RIP, RNA pull-down, and ChIP assays. Results The differentially expressed lncRNA XIST was determined in OA. In addition, cartilage tissues of OA showed upregulation of lncRNA XIST and downregulation of TIMP-3. LncRNA XIST was primarily localized in the nucleus and was capable of binding to the promoter of TIMP-3. The silencing of lncRNA XIST decreased the methylation levels of TIMP-3 promoter and increased the expressions of TIMP-3, which consequently inhibited collagen degradation in OA chondrocytes. Furthermore, TIMP-3 over-expression reversed the effect of lncRNA XIST on collagen degradation in OA chondrocytes. Conclusion Collectively, lncRNA XIST raises collagen degradation in OA chondrocytes after tibial plateau fracture by accelerating the methylation of TIMP-3 promoter by recruiting DNA methyltransferase.

A novel Ag3PO4/Nb2O5 fiber composite was fabricated through depositing Ag3PO4 nanoparticles on Nb2O5 fiber surfaces through a facile depositing precipitation approach. The as-prepared Ag3PO4/Nb2O5 photocatalyst was characterized through XRD, SEM, XPS and UV-Vis measurements. SEM results show that biomorphic Nb2O5 fibers have a wrinkled surface and porous walls. The special morphology of the Nb2O5 fibers provided a large amount of voids and interfaces in favor of decorating with Ag3PO4 nanocrystals. The Ag3PO4/Nb2O5 composite photocatalyst exhibits much higher photocatalytic activity for the degradation of rhodamine B than pure Ag3PO4 under simulated sunlight. Such superior photocatalytic activity is mainly attributed to enhanced visible light absorption and effective separation of photogenerated electron–hole pairs derived from the Ag3PO4/Nb2O5 heterojunction. No loss of photocatalytic activity has been observed after four recycles. Moreover, the large size of the Ag3PO4/Nb2O5 composite allows it to be easily separated from the solution.

Visible light driven BiOBr/rod-like BiPO4 composites with different BiOBr to BiPO4 molar ratios were fabricated via a facile deposition-precipitation method. X-ray powder diffraction, field emission scanning electron microscopy, transmission electron microscopy, UV-Vis diffuse reflectance spectroscopy and Brunauer–Emmett–Teller surface area were used to characterize the as-synthesized samples. Results showed that the BiOBr/rod-like BiPO4 composite with equal mole ratio exhibited the best photocatalytic performance for rhodamine B (RhB) degradation under visible light irradiation. The enhanced photocatalytic performance could be mainly attributed to the effective separation of the photogenerated electrons and holes at the heterojunction interface of p-BiOBr and n-BiPO4.

Cotton was used as template for the fabrication of a biomorphic Nb2O5 photocatalyst with hexagonal and orthorhombic structures. The as-prepared Nb2O5 was characterized through X-ray diffraction (XRD), scanning electron microscopy (SEM), specific surface area and UV-Vis diffused reflectance spectra measurements. The photocatalytic activity of the Nb2O5 fibers was evaluated through degradation of methylene blue (MB) in aqueous solution exposed to UV light. SEM results show that biomorphic Nb2O5 fibers are both hollow and have porous walls. The architectures allow a more accessible surface for the photocatalytic decomposition of dyes molecules. The photocatalytic activity of physically mixed fibers with 75% H-Nb2O5 and 25% O-Nb2O5 phases is superior to those of pure H- and O-Nb2O5 phases, and other samples with different H- and O-Nb2O5 ratios. Such superior photocatalytic activity is mainly due to an optimal balance between the adsorption of MB and the absorption of UV light. Moreover, the large size of the Nb2O5 hollow fibers allows them to be easily separated from the solution.