Background

The rising challenges of antibiotic resistance and cancer necessitate the development of sustainable, cost-effective, and multifunctional therapeutic agents. This study introduces a green synthesis approach for bimetallic nanoparticles (BNPs) using agro-waste materials.

Results

For the first time, bimetallic titanium dioxide–zinc oxide (TiO2-ZnO) BNPs were synthesized using onion peel extract as a natural reducing and stabilizing agent. UV–Vis spectroscopy confirmed nanoparticle formation with a peak corresponding to a size of approximately 320 nm. DLS showed an average hydrodynamic diameter of 145.1 nm, and TEM revealed monodispersed nanoparticles, ranging from 80 to 150 nm. The BNPs exhibited broad-spectrum antimicrobial activity with MIC values of 500 μg/mL against Bacillus subtilis, Pseudomonas aeruginosa, and Candida albicans; 1000 μg/mL against Staphylococcus aureus; and 250 μg/mL against Escherichia coli. They also demonstrated significant antibiofilm activity against B. subtilis-MRSA with a 63.1% inhibition rate at 125 μg/mL. Additionally, TiO2-ZnO BNPs showed potent cytotoxic effects on MCF-7 breast cancer cells, with an IC50 of 5.97 ± 0.37 μg/mL, and anticancer activity was mediated by caspase-8 activation and VEGFR-2 downregulation.

Conclusions

This green-synthesized TiO2-ZnO BNPs offer a promising dual-function nanoplatform for combating microbial infections and cancer, highlighting the potential of sustainable nanotechnology for biomedical applications.

How to cite: Saied E, Doghish AS, Soliman MK, et al. Onion peel-mediated biosynthesis of TiO2-ZnO bimetallic nanoparticles: Antimicrobial, antibiofilm, and anticancer activities. Electron J Biotechnol 2025;77. https://doi.org/10.1016/j.ejbt.2025.06.001.