摘要Objective:To determine the efficacies of antibacterial and antioxidant activities of aqueous leaf extract ofPsidium guajava mediated biosynthesis of titanium dioxide nanoparticles(TiO2NPs). Methods:SynthesizedTiO2NPs were tested by disc diffusion method against against human pathogenic bacteria.The total antioxidant activity and phenolic content(Folin-Ciocalteau method) of synthesizedTiO2NPs and aqueous plant extract were determined.The scavenging radicals were estimated byDPPH method.The synthesizedTiO2NPs were characterized byXRD, FTIR,FESEM andEDX.Results:FTIR spectra of synthesizedTiO2NPs exhibited prominent peaks at3410 cm-1(alkynes),1578 cm-1,1451 cm-1(alkanes), and1123 cm-1(C-O absorption).The morphological characterization of synthesizedTiO2NPs was analysed byFESEM which showed spherical shape and clusters with an average size of32.58 nm.The maximum zone of inhibition was observed in the synthesizedTiO2NPs(20 μg/mL) againstStaphylococcus aureus(25 mm) and Escherichia coli(23 mm).The synthesizedTiO2NPs 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 synthesizedTiO2 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 synthesizedTiO2NPs were found to be85.4 and18.3 mgTA/g, respectively.Conclusions:Green synthesizedTiO2NPs provides a promising approach can satisfy the requirement of large-scale industrial production bearing the advantage of low-cost, eco-friendly and reproducible.