Understanding the synthesis mechanism of arginine functionalized silver/silver chloride nanoparticles using sugar ligands

Abstract

In this study, we performed a mechanistic study to understand how the sugar ligand chemistry affected the morphology, size and surface chemistry of Ag/AgCl_NPs synthesized in the presence of L-Arginine hydrochloride and L-Arginine/KCl mixture. The sugar ligands Lactose p-methoxyaniline (LMA) and Galactose 5-aminosalicylic acid (G5AS) resulted in formation of sheet-like Ag/AgCl_NPs while Lactose sulfanilic acid (LSA) and Lactose p-sulfonyldianiline (LPSA) caused the formation of anisotropic and film-like Ag/AgCl_NPs. The UV-Vis based mechanistic studies showed that the presence of Arginine posed a strong effect on how G5AS and LMA ligands interact with silver ions while the effect was more complicated for the LSA and LPSA ligands due to the fact that they form complexation with Ag⁺ ions. The mechanism was further investigated using infrared (IR) studies that showed the increases in Argine and chloride ion concentrations resulted in differentiation of the surface chemistry of the Ag/AgCl_NPs, and appearance of Arginine related IR bands became clearer in the case of co-introduction of Arginine and the sugar ligands. The characterized nanoparticles were then used as antibacterial agent for multidrug resistant Escherichia coli species for which less than 10 µM minimum inhibitory concentrations were obtained. The promising antibacterial activity, which could be assigned to the presence of Arginine, was independent from the sugar ligand chemistry and nanoparticles’ morphology and size. Particularly, large Ag/AgCl_NP film forming capacity can call further research to be exploited as coating materials for antibacterial application.