Antioxidant and Antimicrobial Properties of TiO2-ZnO Bimetal Nanoparticle Synthesized Using Leucas aspera L. Flower Extract

Aims: This study focuses on the biosynthesis of titanium dioxide (TiO₂) and zinc oxide (ZnO) bimetal nanoparticles using Leucas aspera L. flower extract and their evaluation for antioxidant and antimicrobial properties. Study Design: This study follows an experimental laboratory-based design focusing on the green synthesis, characterization, and bioactivity evaluation of TiO₂-ZnO bimetal nanoparticles using Leucas aspera L. flower extract, with assessments including UV-Vis, FTIR, SEM, antioxidant, antimicrobial, and MIC assays. Place and Duration of Study: The study was conducted at CBNR Institute, Coimbatore, over a period of January to March 2025. Methodology: Fresh Leucas aspera L. flowers were collected from Kallakurichi, Tamil Nadu, India, and The extract was used for the green synthesis by TiO₂ and ZnO. The synthesized bimetal nanoparticles were characterized using UV-Vis spectroscopy, FTIR, and SEM analysis. The antioxidant activity was assessed using the Phosphomolybdenum method. Antibacterial and antifungal activities were evaluated against S. aureus, K. pneumoniae, P. aeruginosa, A. niger, A. terreus, and A. flavus. Minimum inhibitory concentration (MIC) was determined using a biofilm assay with S. aureus. Results: The UV-Vis spectroscopic analysis confirmed the synthesis of TiO₂-ZnO nanoparticles with an absorption peak at 315 nm. The total antioxidant activity of the aqueous flower extract shows efficient activity while the nanoparticle extract showed a reduced activity. The antibacterial results revealed that nanoparticles exhibited significant inhibition against S. aureus (26 mm), K. pneumoniae (21 mm), and P. aeruginosa (22 mm), whereas the flower extract showed minimal activity. The antifungal study indicated that A. niger and A. terreus were susceptible to nanoparticles. MIC analysis demonstrated a dose-dependent inhibition of S. aureus, with a maximum cell death of 54.45% at 10 µg/ml. Conclusion: The biosynthesized TiO₂-ZnO bimetal nanoparticles exhibited superior antibacterial and antifungal properties compared to the flower extract. The study highlights the potential of Leucas aspera L. extract-mediated nanoparticles as effective antimicrobial agents for biomedical applications.