Investigating the antioxidant and antimicrobial properties of silver nanoparticles synthesized using the alcoholic extract of Spirulina subsalsa algae

Objective: Silver nanoparticles (AgNPs) are valuable commercial nanomaterials due to their unique biological properties. As bacteria become more resistant to synthetic antibiotics, exploring natural alternatives such as essential oils, plant extracts, and mineral substances has become essential. Algae, which are diverse and widespread, are noteworthy for their antibacterial and antioxidant properties. This study focused on creating AgNPs using Spirulina algae alcoholic extract and examining their antibacterial and antioxidant properties. Materials and Methods: AgNPs were synthesized by the green method and evaluated by Fourier Transform Infrared Spectroscopy (FT-IR), Dynamic Light Scattering (DLS), and Transmission Electron Microscopy) TEM(. The green synthesis was evaluated at 400-450 nm using a spectrophotometer. Then, the total phenol and flavonoid content of AgNPs were measured. The Diphenyl Picryhydrazyl (DPPH) test was used to evaluate the antioxidant properties. The antimicrobial activity of nanoparticles against Staphylococcus aureus and Pseudomonas aeruginosa was investigated by Minimum Inhibitory Concenteration (MIC) and Minimum Bacteriocidal Concentration (MBC) tests. Results: The FT-IR results demonstrate the successful synthesis of AgNPs with unique covalent bonding. DLS analysis also confirms spherical nanoparticle morphology and uniform 15-20 nm distribution. In MIC/MBC results, the antibacterial effect of AgNPs was observed within the first few hours (1 to 5 hours), reaching its peak at 24, 48, and 72 hours. Nanoparticles significantly inhibited the growth and survival of both gram-positive and Gram-negative bacteria. Conclusion: Green-synthesized AgNPs have antibacterial effects in addition to antioxidant capabilities. As they can kill both gram-positive and gram-negative bacteria, these nanoparticles might be a great alternative to conventional antibiotics.