Synthesis and characterizations of highly stable magnetite-silver (Fe3O4-Ag) nanohybrid for recyclable antibacterial materials

Due to their excellent antimicrobial activity, silver nanoparticles are considered as promising candidates against resistant pathogens. For such biological applications, it is of great importance to separate these nanoparticles from the surrounding media to prevent the potential contamination or aggregation. The Fe3O4 nanoparticles (Fe3O4NPs) are the mostly used magnetic materials in such fields, due to their biocompatibility, well-known chemistry/synthesis methods, and high surface area which allows to load many antibacterial agents on their surface [1]. In this research, highly stable silver nanoparticles, AgNPs-3MPS (3-MPS: 3- mercapto-1-propanesulfonate) were chemically decorated on the surface of silane-functionalized Fe3O4NPs. The (3-mercaptopropyl)trimethoxysilane (MPTS) was used for the silane functionalization to provide the free –SH groups on the Fe3O4NPs suitable for the chemical conjugation of AgNPs-3MPS with the magnetite surface. The Fe3O4NPs were synthesized by a coprecipitation of Fe(II) and Fe(III) ions in the presence of polyacrylic acid (PAA) as coating agent, followed by the surface silanization using a sol-gel method. Then AgNPs-3MPS were prepared in situ (reducing agent: NaBH4) and directly attached to the free –SH groups of Fe3O4NPs-PAA@MPTS forming the final nanohybrid. The stability, size, morphology, and chemical composition of both Fe3O4-PAA@MPTS and nanohybrid were evaluated by FT-IR/ATR, FESEM-EDS, DLS characterizations.