Gram-scale synthesis of splat-shaped Ag-TiO2 nanocomposites for enhanced antimicrobial properties

Hydrothermally synthesized Ag-TiO2 nanofibers (NFs) for photocatalytic dye degradation and antibacterial activity

This work successfully utilised eco-friendly green synthesis to produce Ag-TiO₂ nanofibers (NFs). As pollution and energy limitations have become global issues, there is an ongoing need to develop more effective catalysts through straightforward and environmentally friendly methods. The Ag-TiO₂ nanofibers (NFs) XRD pattern exhibits an anatase TiO₂ and FCC crystal structure of Ag nanoparticles. The SEM investigation revealed a nanofiber-like surface morphology. The Ag-TiO₂ nanofibers (NFs) exhibits an optical band gap energy is 2.5 eV. Methylene blue (MB), malachite green (MG), Congo red (CR), and crystal violet (CV) dye aqueous solutions were used to evaluate the photocatalytic performance of the synthesized Ag-modified TiO₂ nanofibers (NFs) under direct sunlight irradiation. The effects of catalyst size on the efficient breakdown of MB dye were also investigated. The optimum catalyst concentration was found to be at 0.02 mg/mL. At 120 min of direct sunlight, the highest photosynthetic degradation efficiency (DE percentage) of 94% was achieved for MB dye. Ag-TiO₂ nanofibers (NFs) have been demonstrated to have exceptional antibacterial activity against Gram-positive bacteria such as Staphylococcus aureus and Gram-negative bacteria E-Coli. Because of these great qualities, it seems likely that the Ag-TiO₂ nanofibers (NFs) made could be a great photocatalyst for getting dye pollutants out of wastewater.

Bioinspired Synthesis of Magnetic Nanoparticles Based on Iron Oxides Using Orange Waste and Their Application as Photo-Activated Antibacterial Agents

Magnetic nanoparticles based on iron oxides (MNPs-Fe) have been proposed as photothermal agents (PTAs) within antibacterial photothermal therapy (PTT), aiming to counteract the vast health problem of multidrug-resistant bacterial infections. We present a quick and easy green synthesis (GS) to prepare MNPs-Fe harnessing waste. Orange peel extract (organic compounds) was used as a reducing, capping, and stabilizing agent in the GS, which employed microwave (MW) irradiation to reduce the synthesis time. The produced weight, physical-chemical features and magnetic features of the MNPs-Fe were studied. Moreover, their cytotoxicity was assessed in animal cell line ATCC RAW 264.7, as well as their antibacterial activity against Staphylococcus aureus and Escherichia coli. We found that the 50GS-MNPs-Fe sample (prepared by GS, with 50% v/v of NH₄OH and 50% v/v of orange peel extract) had an excellent mass yield. Its particle size was ~50 nm with the presence of an organic coating (terpenes or aldehydes). We believe that this coating improved the cell viability in extended periods (8 days) of cell culture with concentrations lower than 250 µg·mL^-1, with respect to the MNPs-Fe obtained by CO and single MW, but it did not influence the antibacterial effect. The bacteria inhibition was attributed to the plasmonic of 50GS-MNPs-Fe (photothermal effect) by irradiation with red light (630 nm, 65.5 mW·cm^-2, 30 min). We highlight the superparamagnetism of the 50GS-MNPs-Fe over 60 K in a broader temperature range than the MNPs-Fe obtained by CO (160.09 K) and MW (211.1 K). Therefore, 50GS-MNPs-Fe could be excellent candidates as broad-spectrum PTAs in antibacterial PTT. Furthermore, they might be employed in magnetic hyperthermia, magnetic resonance imaging, oncological treatments, and so on.

Titanium dioxide nanoparticles: Recent progress in antimicrobial applications

For decades, the antimicrobial applications of nanoparticles (NPs) have attracted the attention of scientists as a strategy for controlling the ever-increasing threat of multidrug-resistant microorganisms. The photo-induced antimicrobial properties of titanium dioxide (TiO₂ ) NPs by ultraviolet (UV) light are well known. This review elaborates on the modern methods and antimicrobial mechanisms of TiO₂ NPs and their modifications to better understand and utilize their potential in various biomedical applications. Additional compounds can be grafted onto TiO₂ nanomaterial, leading to hybrid metallic or non-metallic materials. To improve the antimicrobial properties, many approaches involving TiO₂ have been tested. The results of selected studies from the past few years covering the most recent trends in this field are discussed in this review. There is extensive evidence to show that TiO₂ NPs can exhibit certain antimicrobial features with disputable roles of UV light. Hence, they are effective in treating bacterial infections, although the majority of these conclusions came from in vitro studies and in the presence of some additional nanomaterials. The methods of evaluation varied depending on the nature of the research while researchers incorporated different techniques, including determining the minimum inhibitory concentration, cell count, and using disk and well diffusion methods, with a noticeable indication that cell count was the most and dominant criterion used to evaluate the antimicrobial activity. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Emerging Technologies Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease.