Microwave-Assisted Biosynthesis of Silver Nanoparticles Using Chlorella sp. for Antibacterial and Cytotoxicity Effects of Breast Cancer Cell Line

Microwave-assisted biosynthesis using marine <i>Chlorella</i> sp. extracts provides a green and efficient route for the production of silver nanoparticles (AgNPs). Compared with the conventional method (24 h), microwave-assisted synthesis reduces the reaction time to less than 7 min while producing smaller and more uniformly distributed nanoparticles. AgNPs were synthesized using extracts obtained with different solvents and directly compared with those produced via the conventional method to substantiate the efficiency of the microwave-assisted approach. UV-visible spectroscopy confirmed rapid nanoparticle formation, exhibiting surface plasmon resonance peaks in the range of 405 to 427 nm. TEM analysis revealed predominantly spherical AgNPs with particle sizes of approximately 10 to 20 nm. The XRD and FTIR analyses confirmed their crystalline structure and stabilization by algal-derived functional groups. The biological activities of the AgNPs were dependent on the extraction solvent. AgNPs synthesized using hexane extracts exhibited pronounced antibacterial activity, achieving minimum inhibitory concentrations as low as 0.31 µg/mL. In addition, the AgNP induced concentration-dependent cytotoxic effects in human breast cancer cell lines. IC₅₀ values, determined via dose-response analysis, ranged from 0.18 to 0.67 μg/mL in MDA-MB-231 cells and 1.70 to 8.42 μg/mL in MCF-7 cells. These results indicate a potent cytotoxic profile, with MDA-MB-231 cells exhibiting significantly higher sensitivity to the microwave-assisted formulations. Collectively, these findings highlight microwave-assisted algal-mediated biosynthesis as a sustainable and effective platform for generating bioactive AgNPs with promising antibacterial and anticancer potential.