Green synthesis of Ginkgo biloba-mediated magnetite (Fe3O4) nanoparticles: multifunctional antimicrobial, anticancer, and antioxidant activities with molecular mechanistic insights.

The emergence of multidrug-resistant pathogens and the growing burden of cancer necessitate innovative therapeutic strategies. Green nanotechnology offers sustainable approaches to synthesize biocompatible nanomaterials with enhanced biological activities. This study reports the biosynthesis, comprehensive characterization, and multifunctional biological evaluation of Ginkgo biloba-mediated magnetite nanoparticles GB-Fe3O4NPs synthesized via alkaline co-precipitation. Phytochemical profiling through HPLC identified key phenolics (chlorogenic acid 28.70%, hesperetin 28.25%) responsible for NP stabilization and bioactivity. Physicochemical characterization using X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy with energy-dispersive X-ray spectroscopy, transmission electron microscopy, dynamic light scattering, and zeta potential analysis confirmed the formation of crystalline, quasi-spherical nanoparticles with primary sizes ranging from 15 to 70 nm, hydrodynamic diameter of 122.5 nm, and superior colloidal stability (- 45.6 mV). The GB-Fe3O4NPs demonstrated moderate broad-spectrum antimicrobial activity against Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans, and Aspergillus brasiliensis, with inhibition zones of 13.7-18.5 mm and minimum inhibitory concentrations of 312.5-1000 µg/mL, significantly surpassing the parent extract. Time-kill assays revealed rapid bactericidal and fungicidal effects with greater than five-log reductions within 24 h. Preliminary cytotoxicity evaluation against HepG2 hepatocellular carcinoma cells yielded an IC₅₀ of 97.12 µg/mL, while flow cytometry demonstrated substantial apoptosis induction with 78% total apoptotic cells. The nano formulation exhibited moderate antioxidant capacity with 87% DPPH radical scavenging. Molecular docking analysis revealed favorable binding affinities of GB-Fe3O4NPs and phytochemicals to microbial DNA-processing enzymes, elucidating multi-target mechanisms. These findings establish GB-Fe3O4NPs as promising theragnostic agents for antimicrobial and anticancer applications, warranting further in vivo validation for clinical translation.