Novel trimetallic (TiO ₂ –MgO–Au) nanoparticles: Biosynthesis, characterization, antimicrobial, and anticancer activities

Abstract Trimetallic nanoparticles have garnered significant attention due to their promising biological activities. In this study, the aqueous extract of banana peel was utilized as a reducing and stabilizing agent for the green synthesis of novel trimetallic titanium dioxide–magnesium oxide–gold nanoparticles (TiO 2 –MgO–Au NPs). The biosynthesized nanoparticles were spherical, with an average size of 55 nm as observed by transmission electron microscopy and 70 nm based on dynamic light scattering measurements. Antimicrobial tests revealed that the nanoparticles exhibited minimum inhibitory concentration values of 500 µg·mL −1 against Bacillus subtilis and Escherichia coli , 250 µg·mL −1 against Pseudomonas aeruginosa and Candida albicans , and 125 µg·mL −1 against Staphylococcus aureus . The nanoparticles demonstrated significant antibiofilm activity, inhibiting methicillin-resistant S. aureus biofilm formation by 86.8% at 250 µg·mL −1 and by 25.1% at 15.62 µg·mL −1 . The MTT assay showed strong cytotoxic effects on MCF-7 and HepG2 cancer cells, with the lowest IC 50 value of 11.09 ± 1.02 µg·mL −1 observed in MCF-7 cells. Additionally, ELISA results confirmed that TiO 2 –MgO–Au NPs enhanced the activation of caspase-8 while reducing the levels of VEGFR-2. In conclusion, the biosynthesized TiO 2 –MgO–Au NPs showed significant antimicrobial, antibiofilm, and anticancer potential, particularly against breast cancer cells, indicating their potential as a novel therapeutic agent.