Magnetoplasmonic core–shell structured Ag@Fe3O4 particles synthesized via polyol reduction process rendering dual-functionality for bacteria ablation and dyes degradation

The Ag nanoparticles demonstrate potent bacteria eradication capabilities; however, their tendency to aggregate in aqueous solutions compromises the antibacterial efficacy. Furthermore, the Ag nanoparticles employed in sewage treatment are challenging to recycle, resulting in environmental pollution and resource wastage. Herein, the Ag-core Fe₃O₄-shell structured particles (Ag@Fe₃O₄) are synthesized by leveraging the reduction potential difference between Ag⁺/Ag⁰ and Fe³⁺/Fe²⁺ through a one-step polyol reduction process. The Fe₃O₄ shell in the Ag@Fe₃O₄ composite not only effectively inhibits the agglomeration of Ag, but also enhances the penetration capability of the composite into biofilms, thereby enabling Ag@Fe₃O₄ to possess remarkable antibacterial efficacy against Escherichia coli (E. coli). The Ag@Fe₃O₄ demonstrates nearly 100 % inhibition of E. coli at a concentration of 0.24 mg mL⁻¹ (with an Ag content of 0.042 mg mL⁻¹) while still maintaining antibacterial effectiveness of 74.6 % even after undergoing reutilization for 10 cycles. Meanwhile, due to the excellent electron conductivity of Ag and the effective adsorption capability of Fe₃O₄ shell towards organic dyes, Ag@Fe₃O₄ facilitates rapid electron transfer to organic dyes and further lead to their reduction and degradation in the presence of NaBH₄. The Ag@Fe₃O₄ can catalytically degrade various organic dyes (including Rhodamine B, Rhodamine 6G, and Methylene blue) within only 15 min, while achieving an impressive degradation efficiency exceeding 90.9 % after 6 cycles of reutilization. The cost-effectiveness (approximately $0.17 per gram), facile magnetic recovery, along with the superior antibacterial and dye-degradation performance showcase the significant potential of Ag@Fe₃O₄ for medical applications and sewage treatment.