Biogenic TiO2 Nanoparticles for Advanced Antimicrobial and Antiviral Applications

Titanium dioxide, which is nontoxic and abundant in nature, has excellent optical and physicochemical properties. Hence, titanium dioxide nanoparticles (TiO2NPs) are generally applied as photocatalysts because of their non-toxicity, chemical stability, resistance to corrosion, and low-cost requirement for production. However, recent studies on the biogenic synthesis of TiO2NPs reported its potential antimicrobial activities. Thus, this chapter explains the application of TiO2NPs to inhibit various bacterial and fungal pathogens. Certain bacteria such as Acinetobacter baumannii S1, Acinetobacter seohaensis N3, Aeromonas hydrophila, Bacillus cereus A1, Bacillus mycoides, Rummeliibacillus pycnus M1, and Streptomyces sp. HC1 are reported to synthesize mostly spherical TiO2NPs that can vary from 20 to 80 nm in size. Likewise, fungi such as Aspergillus flavus, Fomes fomentarius, Fomitopsis pinicola, and Trichoderma citrinoviride can also synthesize therapeutically active TiO2NPs. Medicinal plants have rich phytochemistry that has been exploited for the synthesis of TiO2NPs. Certain plants such as Azadirachta indica, Ledebouria revoluta, Luffa acutangula, Mentha arvensis, Ocimum americanum, Piper betel, Prunus yedoensis, and Trigonella foenum-graecum can also synthesize TiO2NPs where extracts of different plant parts are used. The biogenic TiO2NPs are reported to inhibit pathogenic bacteria such as Bacillus cereus, Clostridium perfringens, Clostridium tetani, Enterococcus faecalis, Escherichia coli, Klebsiella pneumoniae, Proteus vulgaris, Pseudomonas aeruginosa, Salmonella paratyphi, Salmonella typhi, Staphylococcus aureus, Streptococcus pneumoniae, Streptococcus pyogenes, Vibrio cholerae, and Yersinia enterocolitica. Similarly, biologically fabricated TiO2NPs can effectively inhibit pathogenic fungi such as Aspergillus niger and Candida albicans. Hence, a further in-depth understanding of the mechanism of action of TiO2NPs against all these bacterial and fungal pathogens can help to develop broad-spectrum novel nanomedicine in future. Furthermore, there is a great scope in future for exploring the antiviral properties of the biogenic TiO2NPs.