Adenosine monophosphate assisted homogeneous silica coating of silver Nanoparticles in high-yield and their antibacterial activity

In this study, we propose a novel approach for the silica coating of silver nanoparticles based on surface modification with adenosine monophosphate (AMP). Upon AMP stabilization, the nanoparticles can be transferred into 2-propanol, promoting the growth of silica on the particle surfaces through the standard Stöber process. The obtained silica shells are uniform and homogeneous, and the method allows a high degree of control over shell thickness while minimizing the presence of uncoated NPs or the negligible presence of core-free silica NPs. In addition, AMP-functionalized AgNPs could be also coated with a mesoporous silica coating using cetyltrimethylammonium chloride (CTAC) as a template. Interestingly, the thickness of the mesoporous silica coating could be tightly adjusted by either the silica precursor concentration or varying the CTAC concentration while keeping constant the silica precursor concentration. Finally, the influence of the silica coating on the antimicrobial effect of AgNPs was studied on gram-negative bacteria (R. gelatinous and E. coli) and under different bacterial growth conditions, shedding light on their potential applications in different biological environments.