In this study, the bimetallic silver–cobalt (Ag–Co) nanoparticles were synthesized, evaluated, and investigated via green synthesis using aqueous extract of the red alga Gelidiella sp. and its interactions with human pathogens in a colloidal condition. The marine red algal extract of Gelidiella sp. was used to synthesize the bimetallic nanoparticles of Ag and Co. For this, 50 mL of 10–3 aqueous Ag–Co prepared solutions were combined with 50 mL of pure algal extract. The synthesized Ag–Co bimetallic nanoparticles were characterized by UV–vis, FTIR, XRD, and SEM. The nanoparticles were evaluated for their antioxidant, antibacterial, and cytotoxic activities. The green synthesized Gelidiella sp. bimetallic nanoparticles showed a UV–vis spectrum absorption peak at 578 nm. Analysis of the FTIR spectra verified the functional groups involved in the production of the Ag–Co nanoparticles. The diffraction pattern of silver-cobalt nanoparticles showed diffraction angles at 2θ values of 38.12ο, 44.23ο, 64.52ο, and 77.47ο corresponding to the (111), (200), (220), and (311) lattice planes. The particle size distribution, which ranges from 30 to 80 nm, and the shape were revealed by SEM investigation to be cubic to rhomboidal; thus, they were confirmed to be nanoparticles as well as fine particles/particulate matter. Additionally, the nanoparticles demonstrated antioxidant activity via DPPH, ABTS, and ferrous-reducing power assays. The antibacterial activity was performed against various human pathogens, with the highest zone of inhibition in Pseudomonas aeruginosa and Klebsiella pneumoniae, both gram-negative bacteria. The cytotoxic effect of the synthesized Ag–Co bimetallic nanoparticles against MCF-7 breast cancer cell lines was evaluated using the MTT assay with an IC50 value of 64.08 µg.mL⁻1. Maximum inhibition concentration was observed at 200 µg.mL⁻1. These findings highlight the potential of Gelidiella-mediated Ag–Co bimetallic nanoparticles as effective antimicrobial and anticancer agents, demonstrating significant zones of inhibition against pathogenic bacteria and notable cytotoxicity toward MCF-7 breast cancer cells. Their biogenic synthesis underscores the promising potential of Gelidiella-mediated Ag–Co bimetallic nanoparticles as an environmentally friendly and sustainable approach, aligning with current trends in green nanotechnology.

Modelling and green synthesis of Ag–Co bimetallic nanoparticles using red alga (Gelidiella sp.) and their colloidal interaction with human pathogens

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发表日期：

2025年8月7日

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A. Seethal Papitha,
D. Lakshmi

摘要

In this study, the bimetallic silver–cobalt (Ag–Co) nanoparticles were synthesized, evaluated, and investigated via green synthesis using aqueous extract of the red alga Gelidiella sp. and its interactions with human pathogens in a colloidal condition. The marine red algal extract of Gelidiella sp. was used to synthesize the bimetallic nanoparticles of Ag and Co. For this, 50 mL of 10^–3 aqueous Ag–Co prepared solutions were combined with 50 mL of pure algal extract. The synthesized Ag–Co bimetallic nanoparticles were characterized by UV–vis, FTIR, XRD, and SEM. The nanoparticles were evaluated for their antioxidant, antibacterial, and cytotoxic activities. The green synthesized Gelidiella sp. bimetallic nanoparticles showed a UV–vis spectrum absorption peak at 578 nm. Analysis of the FTIR spectra verified the functional groups involved in the production of the Ag–Co nanoparticles. The diffraction pattern of silver-cobalt nanoparticles showed diffraction angles at 2θ values of 38.12^ο, 44.23^ο, 64.52^ο, and 77.47^ο corresponding to the (111), (200), (220), and (311) lattice planes. The particle size distribution, which ranges from 30 to 80 nm, and the shape were revealed by SEM investigation to be cubic to rhomboidal; thus, they were confirmed to be nanoparticles as well as fine particles/particulate matter. Additionally, the nanoparticles demonstrated antioxidant activity via DPPH, ABTS, and ferrous-reducing power assays. The antibacterial activity was performed against various human pathogens, with the highest zone of inhibition in Pseudomonas aeruginosa and Klebsiella pneumoniae, both gram-negative bacteria. The cytotoxic effect of the synthesized Ag–Co bimetallic nanoparticles against MCF-7 breast cancer cell lines was evaluated using the MTT assay with an IC₅₀ value of 64.08 µg.mL⁻¹. Maximum inhibition concentration was observed at 200 µg.mL⁻¹. These findings highlight the potential of Gelidiella-mediated Ag–Co bimetallic nanoparticles as effective antimicrobial and anticancer agents, demonstrating significant zones of inhibition against pathogenic bacteria and notable cytotoxicity toward MCF-7 breast cancer cells. Their biogenic synthesis underscores the promising potential of Gelidiella-mediated Ag–Co bimetallic nanoparticles as an environmentally friendly and sustainable approach, aligning with current trends in green nanotechnology.