Phytosynthesis of anatase TiO₂ nanostructures using grapefruit extract for antimicrobial and catalytic applications

Plant extracts have been broadly considered to be an environmentally-benign alternative for the in vitro synthesis of stable and shape-controlled metal and metal oxide nanoparticles. In this study, a green procedure based on using grapefruit juice extract was applied in the phytosynthesis of TiO₂ nanostructures. The prepared samples, calcined at 600 °C, were subjected to various physicochemical characterisations using FT-IR, Raman, XRD, SEM and XPS. Structural characterisation confirmed the formation of a temperature-stable monophasic anatase polymorph TiO₂. The SEM morphological analysis revealed that the synthesised nanoparticles had an almost spherical shape. The antimicrobial activity of the phytosynthesised TiO₂ nanostructures was evaluated against gram-positive (E. coli and K. pneumoniae) and gram-negative (Methicillin-resistant Staphylococcus aureus: MRSA) bacterial and fungal (C. Albicans) pathogens in terms of MIC measurements. Overall, the phytosynthesised nanoparticles exhibited high antibacterial power towards gram-positive and gram-negative bacteria but were inactive against C. albicans. Additionally, an evaluation of the phytoprepared nanostructures determined that they exhibited good catalytic performance.