Eco-friendly synthesis of silver nanoparticles using Eisenia bicyclis seaweed, their antimicrobial and anticancer activities

Silver nanoparticle (AgNPs) production with antibacterial and antitumor properties is an important application in the medical field. This study introduces a novel organism that can be used for the large-scale production of AgNPs. The edible brown alga Eisenia bicyclis was used as a reducing agent to biosynthesize stable AgNPs. In this study, we achieved producing 50 mg AgNPs using only 1 g dried E. bicyclis seaweed. AgNP biosynthesis was performed at optimized conditions of a reaction temperature of 90°C, a seaweed extract concentration of 0.4%, and an AgNO3 concentration of 0.5 mM within 20 min, and the results showed that the formed nanoparticles are spherical and monodispersed with an average size 18.5 ± 1.2 nm. The antibacterial activity of biosynthesized AgNPs was evaluated against some human clinical pathogens. Results showed that AgNPs had antibacterial activity against all tested bacterial strains, with the appearance of a clear zone equal to or larger than positive controls. Also, there was a concentration-dependent growth inhibition of in vitro cultured breast cancer cells treated with AgNPs and overexpression of p53 and Bax, and underexpression of Bcl-2. AgNPs synthesized by this method provide a potential source for antibacterial and anticancer applications.