From Flower to Medicine: Green-Synthesized Silver Nanoparticles as Promising Antibacterial Agents

Background: Breast cancer and chronic bacterial infections are pressing global health issues, and traditional treatments are often hampered by resistance and adverse side effects. This study sought to create silver nanoparticles (AgNPs) through eco-friendly synthesis using Hibiscus rosa sinensis (HRS) flower extract and to assess their antibacterial, antibiofilm, and anticancer properties. Methods: HRS extract functioned as both a reducing and stabilizing agent in the synthesis of AgNPs. The nanoparticles were characterized using ultraviolet-visible spectroscopy (UV-Vis), Fourier-transform infrared (FTIR) spectroscopy, and transmission electron microscopy (TEM). Antibacterial and antibiofilm properties were evaluated against gram-positive (Staphylococcus aureus and Enterococcus faecalis) and gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria using agar well diffusion and XTT reduction assays. The cytotoxic effects on MDMB-231 breast cancer cells and normal splenocytes were measured using the MTT assay, whereas fluorescence microscopy was used to observe reactive oxygen species (ROS) production, changes in mitochondrial membrane potential, and caspase-3 activation. Results: The synthesized HRS-AgNPs, primarily ranging from 10 to 50 nm, displayed a distinct surface plasmon resonance (SPR) peak at 428 nm. They exhibit notable antibacterial activity, especially against gram-positive bacteria, and effectively disrupt bacterial biofilms. Cytotoxicity evaluations showed that HRS-AgNPs decreased the viability of MDMB-231 cells in a dose-dependent manner, with minimal toxicity observed in normal splenocytes. The increase in ROS levels, reduction in mitochondrial membrane potential, and heightened caspase-3 activity collectively suggest apoptosis-driven cell death in cancer cells. Conclusions: HRS-AgNPs demonstrated dual functionality, with strong antibacterial and selective anticancer effects. Their environmentally friendly synthesis, stability, and significant biological activities suggest their potential for further development, including in vivo safety and efficacy assessments for clinical applications in treating infections and breast cancer.