Degradation of graphene oxide-silver nanoparticles by hypochlorite: impacts on physicochemical properties, antimicrobial activity and ecotoxicity

Graphene oxide-silver nanoparticles (GO-AgNPs) represent a promising hybrid material for developing composites, sensors, catalysts, and antimicrobial systems. However, their degradation and life cycle remain poorly understood. Herein, this study investigated the chemical degradation of GO-AgNPs by sodium hypochlorite (NaClO) and evaluated the resulting impacts on their colloidal stability, antimicrobial activity, and ecotoxicological effects. This oxidative degradation was monitored over 10 days at room temperature, revealing a progressive transformation of both hybrid components. The process induced structural defects and pores within the GO flakes, while simultaneously altering the AgNP surfaces, with both components exhibiting a reduction in size as the reaction progressed. These transformations significantly compromised colloidal stability—as evidenced by a decrease in zeta potential magnitude—leading to particle aggregation even in ultrapure water. Although pristine GO-AgNPs exhibited exceptional activity against microorganisms, this efficacy was entirely lost post-degradation. Furthermore, while degradation mitigated the acute aquatic toxicity toward Daphnia similis , the transformed material significantly affects the feeding behavior of this model organism. Overall, this study provides crucial insights into the degradation mechanisms of GO-AgNPs, directly contributing to life cycle assessment frameworks and safe-and-sustainable by design approaches for nanomaterials.