One-step method to prepare core-shell magnetic nanocomposite encapsulating silver nanoparticles with superior...

A facile one-step method for synthesis of magnetic core-shell nanocomposite composed of h-Fe₃O₄ (hollow Fe₃O₄) core and stable PDA (polydopamine) shell with functional Ag NPs (silver nanoparticles) evenly distributed between them is developed. The h-Fe₃O₄@Ag/PDA nanocomposite showed excellent catalytic activity in the reaction for reducing azo dyes (methyl orange, methylene blue, and congo red), and the ratios of k values to the weight of h-Fe₃O₄@Ag/PDA were calculated to be 0.302, 0.0545, and 0.895 min^-1 mg^-1, respectively. Besides, the h-Fe₃O₄@Ag/PDA nanocomposite also exhibited good antibacterial activity in the experiment of culturing Bacillus subtilis, and the MIC (minimum inhibitory concentration) was as low as 12.5 μg/mL. Because the Ag NPs will not be leached in the solution under the protection of the PDA shell, the catalytic and antibacterial activities of h-Fe₃O₄@Ag/PDA nanocomposite could maintain more than 90% after five cycles. Intriguingly, this simple synthetic method can be extended to fabricate different multifunctional nanocomposites such as the spherical SiO₂@Ag/PDA and rod-like Fe₂O₃@Ag/PDA. Overall, the facile fabrication process, the superior catalytic and antibacterial activity, and the excellent stability, endow the h-Fe₃O₄@Ag/PDA to be a promising nanocomposite.