Screening, characterisation and bioactivities of green fabricated TiO₂ NP via cyanobacterial extract

The present study was aimed at exploring 37 strains of cyanobacteria for the biofabrication of TiO₂ NP and evaluation of their antioxidant, antifungal, antibacterial and hemolytic activity. Screening of cyanobacterial strains was done via SEM, followed by optimisation and characterisation of the best strain. Synechocystis NCCU-370 appeared as the best strain for the synthesis of TiO₂ NP in terms of size (73.39 nm) and time (24 h) after screening. Following optimisation, nanoparticles were synthesised in 12 h having an average grain size of 16 nm. The aqueous extract preparation required heating of 5 mg/ml of powdered biomass to 60 °C for 10 min. Optimum conditions for the synthesis of TiO₂ NP were found to be pH 7, 30 °C and 12-h cell extract exposure to 0.1 mM of salt. Antioxidant activity was evaluated via DPPH, ABTS and FRAP assay. Antifungal potential was explored against Candida albicans (MIC = 125 µg/ml), Candida glabrata (MIC = 500 µg/ml) and Candida tropicalis (MIC = 250 µg/ml), whereas antibacterial potential was gauged for Bacillus cereus (MIC = 31.25 µg/ml), Escherichia coli (MIC = 31.25 µg/ml) and Klebsiella pneumoniae (MIC = 500 µg/ml) strains. Biogenic TiO₂ NP demonstrated partial synergistic effect and excellent biocompatibility.