Eco-Friendly and Durable Sponge with In Situ Formed Silver Nanoparticles for Antimicrobial Filtration

Microbial contamination poses a significant challenge to the management of water resources and biomedical applications. In this study, the development of a biogenic antimicrobial filtration system has been successfully achieved. This system utilizes a plant extract-mediated synthesis approach for in situ formation of silver nanoparticles (AgNPs) within a porous sponge matrix. The fabrication process involved the immersion of a commercial sponge in an aqueous solution of AgNO3 and plant extract, followed by a thermal treatment. The structural and chemical properties of the Ag@Sponge were then confirmed via a range of analytical methods, including scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). These results indicated the successful incorporation of AgNPs within the sponge, with a predominant spherical morphology and an average size of 54 ± 14 nm. Antimicrobial activity tests demonstrated that Ag@Sponge exhibited significant bacterial and fungal inactivation, achieving >99.99999% microbial reduction against Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), and Candida albicans (C. albicans) (R > 7). Furthermore, the results of filtration experiments demonstrated that microbial removal efficiency increased progressively over six cycles, reaching final reductions of 6.2–6.4 log CFU/mL for E. coli, S. aureus, and C. albicans. Mechanical durability tests confirmed that Ag@Sponge retained >6 log CFU/mL reduction after 5000 cm abrasion (down to 6.6 ± 0.5) and 400 bending cycles (down to 6.1 ± 1.2), indicating strong mechanical resilience and in situ nanoparticle stability. These findings highlight the potential of Ag@Sponge as a sustainable and efficient antimicrobial filtration material for practical applications in water purification and medical decontamination.