Green synthesis of titanium dioxide nanoparticles using Psidium guajava extract and its antibacterial and antioxidant properties

ObjectiveTo determine the efficacies of antibacterial and antioxidant activities of aqueous leaf extract of Psidium guajava mediated biosynthesis of titanium dioxide nanoparticles (TiO₂ NPs).MethodsSynthesized TiO₂ NPs were tested by disc diffusion method against against human pathogenic bacteria. The total antioxidant activity and phenolic content (Folin-Ciocalteau method) of synthesized TiO₂ NPs and aqueous plant extract were determined. The scavenging radicals were estimated by DPPH method. The synthesized TiO₂ NPs were characterized by XRD, FTIR, FESEM and EDX.ResultsFTIR spectra of synthesized TiO₂ NPs exhibited prominent peaks at 3 410 cm^?1 (alkynes), 1 578 cm^?1, 1 451 cm^?1 (alkanes), and 1 123 cm^?1(C-O absorption). The morphological characterization of synthesized TiO₂ NPs was analysed by FESEM which showed spherical shape and clusters with an average size of 32.58 nm. The maximum zone of inhibition was observed in the synthesized TiO₂ NPs (20 μg/mL) against Staphylococcus aureus (25 mm) and Escherichia coli (23 mm). The synthesized TiO₂ NPs showed more antibacterial activity than the standard antibiotic disk, tetracycline which drastically reduces the chances for the development of antibiotics resistance of bacterial species. The plant aqueous extract and synthesized TiO₂ NPs were found to possess maximum antioxidant activity when compared with ascorbic acid. The content of phenolic compounds (mg/g) in leaf aqueous extract and synthesized TiO₂ NPs were found to be 85.4 and 18.3 mgTA/g, respectively.ConclusionsGreen synthesized TiO₂ NPs provides a promising approach can satisfy the requirement of large-scale industrial production bearing the advantage of low-cost, eco-friendly and reproducible.