Core-Shell AgCl@SiO₂ Nanoparticles: Ag(I)-Based Antibacterial Materials with Enhanced Stability

Silver (Ag)-based nanoparticles are one type of highly effective antimicrobial widely used in medical devices, consumer products, and wound dressing. Although Ag(I) rather than Ag(0) is the active species in antibacterial processes, the use of Ag(I) as antibacterial materials is hindered by its instability toward light irradiation. In this paper, we report the fabrication of core-shell AgCl@SiO₂ nanoparticles, which comprise a core of AgCl nanoparticles and a shell of porous silica, for antibacterial applications for the first time. The porous silica shells not only enhance the stability of AgCl by preventing the core from direct light irradiation but also allow active Ag(I) to pass through continuously to inhibit the growth of bacteria. It is worth noting that the synthesis is achieved by a facile one-pot method in which the surfactant hexadecyltrimethylammonium chloride used for the formation of AgCl nanoparticles also acts as a structure-directing agent in the subsequent creation of porous silica. Our results show that the obtained AgCl@SiO₂ nanoparticles exhibit well-defined core-shell structure and are highly efficient in the growth inhibition of Escherichia coli. More importantly, the stability of Ag(I) toward light irradiation is greatly enhanced by the protection of the silica shell. The convenient fabrication, well-defined core-shell structure, and enhanced stability make AgCl@SiO₂ nanoparticles highly promising for antibacterial applications.