The study focused on the green synthesis of lead oxide nanoparticles (PbO-NPs) using green tea extract and its use for photocatalytic degradation. The effect of experimental conditions such as green tea extract concentrations and reaction temperatures on the structure and size of PbO-NPs has been investigated. Reaction temperatures of 25, 50 and 85 ℃ and green tea extract concentrations of 5, 10, 20, 40, 80 and 100 mg/mL were used for preparing of PbO-NPs. Amount of the phenolic acid contained in the green tea extracts was determined according to the Folin-Cioceltau method. The synthesized PbO-NPs were further confirmed by UV–visible Spectroscopy, Fourier Infrared Transformation Spectroscopy (FTIR), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive (EDX) analysis. Tetragonal and orthorhombic morphology of PbO-NPs were observed in SEM images. While the crystallite structure of the PbO-NPs was obtained for the samples prepared using 5 and 10 mg/mL extract concentration for all reaction temperatures, the amorphous structures of PbO-NPs were seen for the samples prepared using extract concentrations of 20, 40, 80 and 100 mg/mL. Finally, PbO-NPs catalyst was tested for the degradation of methylene blue (MB) under UV light. The effect of dye concentration, catalyst amount and pH on degradation were investigated. By determining suitable experimental conditions, MB degradation reached 89% with PbO-NPs in 60 minutes. The reaction kinetics of MB removal from aqueous solution under UV lamp and in the dark media were compared for first-order and second-order reaction kinetics.

Biomaterials are a large group of vitally important materials with many different inorganic and organic types. Biocomposites are produced by using materials such as polymer, metal, and ceramics. Bone tissue engineering deals with materials that can mimic the real bone structure found in the body. These materials used in the human body must be capable of many aspects such as their mechanical strength related to the area where they are used, as well as their properties such as biocompatible, biodegradable, and non-toxic. If the material is intended to treat the bone structure, it should be biodegradable, but it should be resistant to degradation if intended to be used for a long time. With the advance in technology, nanoparticles have become appealing in bone tissue engineering due to their many unique properties. In recent years, mesoporous silica nanoparticles (MSNs) have been prominent biomaterials in the medical field due to their properties such as alterable size structure, large pore volume, and surface area. This study aims to give information about the biomedical properties, synthesis methods, and importance of MSNs with unique properties in bone tissue engineering applications. This study is compiled by examining many studies in the literature.