Olive leaf extract-derived chitosan-metal nanocomposite: Green synthesis and dual antimicrobial-anticancer action

(AgNPs) nanoparticles using olive leaf extract and incorporating them into a chitosan polymer. This approach
combines the biocompatibility of chitosan with the antimicrobial and anticancer properties of metal nanoparticles,
enhanced by the phytochemical richness of olive leaf extract. The significance of our research lies in its
potential to offer a biodegradable and stable alternative to conventional antibiotics and cancer treatments,
particularly in combating multidrug-resistant bacteria and various cancer types. Comprehensive characterization
through Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), Thermogravimetric Analysis
(TGA), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX), and Transmission Electron Microscopy
(TEM) confirmed the successful synthesis of the nanocomposites, with an average size of ~22.6 nm.
Phytochemical analysis highlighted the antioxidant-rich composition of both the olive leaf extract and the
nanoparticles themselves. Functionally, the synthesized nanoparticles exhibited potent antimicrobial activity
against multidrug-resistant bacterial strains, outperforming traditional antibiotics by inhibiting key resistance
genes (ermC, tetX3-q, blaZ, and Ery-msrA). In anticancer assessments, the nanoparticles showed selective
cytotoxicity towards cancer cells in a concentration-dependent manner, with CuNPs and AgNPs showing
particularly strong anticancer effects, while demonstrating minimal toxicity towards normal cells. ZnNPs were
noted for their low cytotoxicity, highlighting the safety profile of these nanoparticles. Further, the nanoparticles
induced apoptosis in cancer cells, as evidenced by the modulation of oncogenes (P21, P53, and BCL2), suggesting
their therapeutic potential. The findings of our study underscore the versatile applications of these biogenic
nanoparticles in developing safer and more effective antimicrobial and anticancer therapies.