Synthesis of Mixed-Phase TiO2-ZrO2 Nanocomposite for Photocatalytic Wastewater Treatment

Bacterial nano-factories as a tool for the biosynthesis of TiO2 nanoparticles: characterization and potential application in wastewater treatment

The development of reliable and eco-conscious processes for nanoparticle synthesis constitutes a significant element in nanotechnology. TiO2 nanoparticles (NPs) are becoming essential due to their potential uses in dentistry, surgery, agriculture, and pharmacy. This leads to the development of various procedures for producing TiO2 NPs using various physicochemical methods. Still, the drawbacks of these conventional methods are associated with the emission of toxic chemicals into the atmosphere and high energy demands in production, hence endangering the health and the environment. Problems issued are solved by green nanotechnology, which offers tools as nano-factories by utilizing biological sources to subside the improper effects of conventional methods and produces nanoparticles through synthesis methods that are clean, safe, energy-efficient, and cost-effective. Among the biogenic sources, microbial cells such as bacteria possess intrinsic pathways of converting metallic salt to nanoparticles due to their ability to produce reductase enzymes. Also, they can offer features to products such as high dispersity and produce sustainable nanoparticles at a large scale. Biosynthesized TiO2 NPs have high oxidizing potential and a wide range of applications, specifically as photosensitizers and antimicrobial agents. This review will address bacterial nano-factories that can be utilized for the biosynthesis of TiO2 NPs, the characterization of biosynthesized nanoparticles, and their potential application in wastewater treatment.

Antimicrobial Cu-Doped TiO2 Coatings on the β Ti-30Nb-5Mo Alloy by Micro-Arc Oxidation

Among the different surface modification techniques, micro-arc oxidation (MAO) is explored for its ability to enhance the surface properties of Ti alloys by creating a controlled and durable oxide layer. The incorporation of Cu ions during the MAO process introduces additional functionalities to the surface, offering improved corrosion resistance and antimicrobial activity. In this study, the β-metastable Ti-30Nb-5Mo alloy was oxidated through the MAO method to create a Cu-doped TiO2 coating. The quantity of Cu ions in the electrolyte was changed (1.5, 2.5, and 3.5 mMol) to develop coatings with different Cu concentrations. X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron and atomic force microscopies, contact angle, and Vickers microhardness techniques were applied to characterize the deposited coatings. Cu incorporation increased the antimicrobial activity of the coatings, inhibiting the growth of Staphylococcus aureus, Enterococcus faecalis, Pseudomonas aeruginosa bacteria strains, and Candida albicans fungus by approximately 44%, 37%, 19%, and 41%, respectively. Meanwhile, the presence of Cu did not inhibit the growth of Escherichia coli. The hardness of all the deposited coatings was between 4 and 5 GPa. All the coatings were non-cytotoxic for adipose tissue-derived mesenchymal stem cells (AMSC), promoting approximately 90% of cell growth and not affecting the AMSC differentiation into the osteogenic lineage.