Heterosigma akashiwo, and Prorocentrum micans microalgae ethanolic extract-based Fe2O3 magnetic nanoparticles: Green synthesis, characterization, antioxidant, and anticancer investigations.

Microalgae's distinct biochemical characteristics and environmental benefits have made them an environmentally acceptable and sustainable platform for the synthesis of nanoparticles (NPs). The current work is in accordance with the principles of green chemistry. This study aims to establish, for the first time, an environmentally sustainable and rapid synthesis route for Fe2O3 using ethanolic extracts of Heterosigma akashiwo (H. akashiwo) and Prorocentrum micans (P. micans) microalgal species. The extracts of H. akashiwo and P. micans serve as natural surfactant-solvent systems for the preparation of Fe2O3/Ha and Fe2O3/Pm NPs respectively. We comprehensively evaluate the structural characteristics, antioxidant potential, and anticancer efficacy of the synthesized NPs. The size of NPs was reported to be 37.8 and 34.9 nm for Fe2O3/Ha and Fe2O3/Pm NPs respectively with varied forms and morphologies. Fe2O3/Ha and Fe2O3/Pm NPs showed moderate antioxidant activity. At 100  µg/mL, their ABTS radical scavenging rates were 54.5 % and 65.9 %, respectively. For DPPH activity, they reached 60.2 % and 59.1 % at 100 µg/mL. In the SOD assay, Fe2O3/Ha and Fe2O3/Pm achieved 21.5 % and 43.8 % scavenging, respectively, compared to 78.2 % for vitamin C. Furthermore, the ability of Fe2O3/Ha and Fe2O3/Pm NPs to suppress the proliferation of HCT-116 (IC50 = 51.54 ± 2.9 and 34.77 ± 2.2  μg/mL, respectively) and HepG-2 (IC50 = 73.13 ± 3.8 and 45.87 ± 2.7  μg/mL, respectively) cancer cells demonstrate their anticancer activity. Fe2O3/Ha and Fe2O3/Pm show reduced cytotoxicity toward normal WI-38 cell line. The results demonstrate the significant antioxidant and anticancer activity of prepared NPs, making them promising candidates for further research and development in biomedical and pharmacological studies.