Author: Devadharshini Manoharan, Gopika Gandhi, Anandhi Anandaraj, Usha Nandhini S, Theboral Jeevaraj and Rajasekar Thirunavukkarasu

DOI: http://doi.org/10.31788/RJC.2026.1919534

Silica nanoparticles (SiNPs) have emerged as pivotal materials in biomedicine and nanotechnology due totheir structural versatility and biocompatibility. This study demonstrates a novel, “green” phycosynthetic route for SiNPs utilizing bioactive pigments extracted from the marine microalgae Picochlorum sp and Chlorellasp. Using sodium silicate as a sustainable precursor, these marine pigments served as natural reductant, dispersant and capping agents, eliminating the need for hazardous chemical reductants. The pigment profiles werevalidated via UV-Visible spectroscopy and High-Performance Liquid Chromatography (HPLC). Systematiccharacterization confirmed the formation of spherical nanoparticles with diameters ranging from100to400nm.UV-Visible spectra exhibited characteristic absorption peaks at 200-250nm, while X-ray Diffraction(XRD) and Fourier-transform infrared (FTIR) spectroscopy verified an amorphous Si-O-Si framework. Thenanoparticles displayed exceptional colloidal stability, with zeta potential values of -46.5mV (Picochlorumsp) and -42.0mV (Chlorella sp). SEM-EDX analysis confirmed a smooth morphology integrated with trace biogenicelements (Mg, Ca) which may enhance biological functionality. Crucially, a hemolysis assay revealed less than5%hemolytic activity at concentrations of 10-20µg/mL, confirming the high biocompatibility of these biogenicSiNPs. These findings spotlight the potential of marine microalgal pigments as a capable bio-factoryfor developing sustainable, non-toxic nanomaterials tailored for biolabeling and biomedical applications.

Keywords: Green synthesis, Marine microalgae, Silica nanoparticles, Phyco-pigments, biocompatibility, Picochlorum sp, Chlorella sp.