Mohsen Mehrabi

Background: Gastric cancer is one of the most common and deadly cancers in the world, and current treatments face challenges such as disease recurrence, drug resistance, and severe side effects. Biosynthesis of metal nanoparticles using natural resources, especially Spirulina algae, is considered a green and promising method for producing novel anticancer agents with less toxicity. Aim: This study aimed to biosynthesize silver oxide (AgO) and copper(II) oxide (CuO) nanoparticles using Spirulina extract and evaluate their anticancer activity on gastric cancer cell line (AGS). Methodology: The nanoparticles were synthesized by green synthesis method using aqueous extract of Spirulina and precursors of silver nitrate and copper salts under heating conditions. Characterization of nanoparticles was performed by UVVis, XRD, FTIR, FESEM, DLS, zeta potential and BET methods. Anticancer activity was evaluated by MTT test and determination of half inhibitory concentration (IC₅₀) on AGS cell line and antibacterial activity was evaluated by MIC and MBC methods on four standard strains. Spherical to elliptical AgO nanoparticles with an average size of 30-70 nm and polyhedral CuO nanoparticles with an average size of 150-80 nm were synthesized. XRD analysis confirmed the formation of pure crystalline phases of silver oxide and copper(II) oxide (tenorite). The zeta potential for AgO and CuO nanoparticles was measured to be -29.69 and -31.85 mV, respectively, indicating good colloidal stability. The specific surface area of CuO nanoparticles (3.6048 m²/g) was significantly higher than that of AgO nanoparticles (2.5430 m²/g). The antibacterial activity of silver oxide nanoparticles was determined with MIC and MBC in the range of 0.97-1.95 and 0.97-81.7 μg/ml, respectively, while copper(II) oxide nanoparticles had no inhibitory or lethal effects up to a concentration of 10 mg/ml. Both nanoparticles showed concentrationdependent anticancer activity. The IC₅₀ value for AgO nanoparticle