Green synthesis of silver-decorated magnetic particles for efficient and reusable antimicrobial activity

Abstract

Metal and metal hybrid nanostructures have shown tremendous application in the biomed-ical and catalytic fields because of their plasmonic and catalytic properties. Here, a green and clean method was employed for the synthesis of silver nanoparticle (Ag NP)-SiO2-Fe2 O3 hybrid microstruc-tures, and biomolecules from green tea extracts were used for constructing the hybrid structures. The SiO2-Fe2 O3 structures were synthesized using an ethanolic green tea leaf extract to form Bio-SiO2-Fe2 O3 (BSiO2-Fe2 O3) structures. Biochemical studies demonstrated the presence of green tea biomolecules in the BSiO2 layer. Reduction of the silver ions was performed by a BSiO2 layer to form Ag NPs of 5–10 nm in diameter in and on the BSiO2-Fe2 O3 microstructure. The reduction process was observed within 600 s, which is faster than that reported elsewhere. The antimicrobial activity of the Ag-BSiO2-Fe2 O3 hybrid structure was demonstrated against Staphylococcus aureus and Escherichia coli, and the nanostructures were further visualized using confocal laser scanning microscopy (CLSM). The magnetic properties of the Ag-BSiO2-Fe2 O3 hybrid structure were used for studying reusable antimicrobial activity. Thus, in this study, we provide a novel green route for the construction of a biomolecule-entrapped SiO2-Fe2 O3 structure and their use for the ultra-fast formation of Ag NPs to form antimicrobial active multifunctional hybrid structures.