Bioactive Molecules of Microalgae Haematococcus pluvialis-Mediated Synthesized Silver Nanoparticles: Antioxidant, Antimicrobial, Antibiofilm, Hemolysis Assay, and Anticancer.

Bioactive molecule-based synthesis of silver nanoparticles (AgNPs) offers an eco-friendly approach with high therapeutic potential; however, research in this area remains limited. This study introduces hot melt extrusion (HME) technology to enhance the extraction efficiency of bioactive compounds, including astaxanthin, from the microalgae Haematococcus pluvialis (Hp). AgNPs were synthesized using HME-processed Hp (H-Hp/AgNPs), confirmed by a color change and UV-vis absorption spectrum. The resulting H-Hp/AgNPs exhibited an average size of 129.7 ± 10.4 nm, a polydispersity index of 0.2 ± 0.3, and a zeta potential of -31.54 ± 0.2 mV, indicating high stability. The synthesized AgNPs demonstrated antibacterial activity by inhibiting the growth and biofilm formation of antibiotic-resistant bacteria. Cell viability assays revealed that normal cells maintained over 100% viability at most concentrations of H-Hp/AgNPs, while cancer cells exhibited significant cytotoxicity (34.1 ± 3.1%) at 250 μg/mL. Furthermore, H-Hp/AgNPs induced apoptosis in MDA-MB 231 cells, as evidenced by mitochondrial membrane potential loss, nuclear condensation, and apoptosis, confirmed through AO/EB, Rh123, and PI staining. Additionally, H-Hp/AgNPs showed no hemolytic activity at concentrations below 250 μg/mL, ensuring safety. In conclusion, this study highlights the potential of biosynthesized H-Hp/AgNPs as promising candidates with antioxidant, antibacterial, biocompatibility, and anticancer properties.