en Bioactive Compounds پژوهشي Research <span style="font-size:9pt"><span style="line-height:150%"><span new="" roman="" style="font-family:" times=""><span style="color:black"><b>Objective:</b> 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<span dir="RTL" lang="AR-SA" style="line-height:150%"><span optima="" style="font-family:">.</span></span></span></span></span></span><br> <span style="font-size:9pt"><span style="line-height:150%"><span new="" roman="" style="font-family:" times=""><span style="color:black"><b>Materials and Methods:</b> AgNPs were synthesized by the green method and evaluated by Fourier Transform Infrared Spectroscopy (FT-IR), Dynamic Light Scattering (DLS), and Transmission Electron Microscopy<span dir="RTL" lang="AR-SA" style="line-height:150%"><span optima="" style="font-family:">)</span></span> TEM<span dir="RTL" lang="AR-SA" style="line-height:150%"><span optima="" style="font-family:">(</span></span>. 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.</span></span></span></span><br> <span style="font-size:9pt"><span style="line-height:150%"><span new="" roman="" style="font-family:" times=""><span style="color:black"><b>Results:</b> 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.</span></span></span></span><br> <span style="font-size:9pt"><span style="line-height:150%"><span new="" roman="" style="font-family:" times=""><span style="color:black"><b>Conclusion:</b> 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.</span></span></span></span><br> &nbsp; Antibacterial agents,Antioxidants,Biosynthesis,Metal nanoparticle,Spirulina 32 42 http://pbp.medilam.ac.ir/browse.php?a_code=A-10-904-1&slc_lang=en&sid=1 Mona babakhani monababakhani7@gmail.com 10031947532846005003 10031947532846005003 No Department of Biotechnology, Faculty of Advanced Science and Technology, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran, Masters degree sepideh khaleghi sp.khaleghi@gmail.com 10031947532846005004 10031947532846005004 No Department of Biotechnology, Faculty of Advanced Science and Technology, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran, Assistant Professor shadi hajrasouliha sh.hajrasouliha@iautmu.ac.ir 10031947532846005005 10031947532846005005 Yes Herbal Pharmacology Research Center, Tehran Medical Sciences, Islamic Azad University,Tehran, Iran, Assistant Professor