Biosynthesis and characterization of silver nanoparticles using polysaccharides from Caulerpa racemosa and evaluation of their antioxidant, antibacterial, and anticancer activities

In recent years, using biological materials to synthesize metallic nanoparticles has emerged as an efficient and cost-effective approach. This work synthesized silver nanoparticles (AgNPs) from Caulerpa racemosa (Cr) - Polysaccharide (Ps). UV–vis spectroscopy examined the synthesised Cr-Ps-AgNPs, revealing a colour shift and a surface plasmon resonance peak at 450 nm. The Fourier transform infrared spectroscopy is used to detect functional groups within the polysaccharide and to investigate nanoparticle interactions. Scanning Electron Microscopy revealed that the biosynthesized Cr-AgNPs varied in size from 32 to 77 nm. X-ray diffraction confirmed that the Cr-Ps-AgNPs were crystalline. Also, dynamic light scattering showed that the Cr-Ps-AgNPs particles, which were biosynthesized nanoparticles, had a size distribution that was polydisperse, with an average diameter of 42.8 nm. In a dose-dependent manner, the biosynthesized Cr-Ps-AgNPs demonstrate high antioxidant activity in the DPPH, reducing power, and total antioxidant scavenging tests. The antibacterial activity of Cr-Ps-AgNPs against Pseudomonas aeruginosa, Klebsiella pneumonia, Staphylococcus aureus, and Streptococcus pyogenes was assessed using an agar well diffusion test, which revealed dose-dependent activity. The cytotoxicity investigation showed a dose-dependent activity against breast cancer cells (MCF-7), with an inhibitory concentration (IC50) of 38 μg/mL. The results of this study show that synthesised Cr-Ps-AgNPs exhibit antioxidant, antibacterial, and anticancer properties.