Fabrication of Graphene-Based TiO2@CeO2 and CeO2@TiO2 Core-Shell Heterostructures for Enhanced Photocatalytic Activity and Cytotoxicity

Development of light-harvesting properties and inhibition of photogenerated charge carrier recombination are of paramount significance in the photocatalytic process. In the present work, we described the synthesis of core-shell heterostructures, which are composed of titanium oxide (TiO₂) and cerium oxide (CeO₂) deposited on a reduced graphene oxide (rGO) surface as a conductive substrate. Following the synthesis of ternary rGO-CeO₂@TiO₂ and rGO-TiO₂@CeO₂ nanostructures, their photocatalytic activity was investigated toward the degradation of rhodamine B dye as an organic pollutant under UV light irradiation. The obtained structures were characterized with high-resolution transmission electron microscopy, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, Brunauer-Emmett-Teller, X-ray photoelectron spectroscopy surface analysis, and UV-Vis spectroscopy. Various parameters including pH, catalyst dosage, temperature, and contact time were studied for photocatalysis optimization. Heterostructures showed considerable advantages because of their high surface area and superior photocatalytic performance. In contrast, rGO-CeO₂@TiO₂ showed the highest photocatalytic activity, which is attributed to the more effective electron-hole separation and quick suppression of charge recombination at core-shell phases. A biological assay of the prepared heterostructure was performed to determine the cytotoxicity against breast cancer cells (MCF-7) and demonstrated a very low survival rate at 7.65% of cells at the 17.5 mg mL^-1 concentration of applied photocatalyst.

Development of Simvastatin Loaded Electrospun Zein Nanofiber Membranes for Bone Repair

The present study aims to prepare and And Characterization of zein nanofibers with simvastatin-loaded in it by electrospinning method using a polymeric matrix prepared from zein solution containing simvastatin antibiotics. The physical, cellular properties and drug release kinetics of the fibers were studied. Fiber formation was investigated by implementing a scanning electron microscope (SEM). The SEM images show a uniform network bead-free fiber structure created from the 1.5% simvastatin/zeinsolution. The viscosity of the 1.5% simvastatin/zein mixture increased to 0.402 P due to the presence of drug in zein solution. Also, the presence of the indicative peaks associated with simvastatin in the Fourier transform infrared (FTIR) spectra of the samples containing the drug, verifies the existence of the drug on the polymeric base of zein/polyethylene oxide (PEO). Also, around 53.887% of the loaded drug was released in the first 12 h of the release kinetics assay and the results of the MTT assay shows reduction in the number of live cells in the test sample. In conclusion, zein nanofibers containing simvastatin drug were found to be potential biodegradable polymers that can find application in bone tissue repair.