Structural evolution of palygorskite-rich clay as the nanocarriers of silver nanoparticles for efficient improving antibacterial activity

Abstract

Clay minerals with rod-like or layered structures have been widely used as the carrier to fabricate metal nanoparticles-based antibacterial composites. Palygorskite-rich clay (PALC) contains not only one-dimensional nanorods (palygorskite) but also two-dimensional nanolamella (mainly illite), where its structure can be regulated by oxalic acid (OA) gradient leaching to obtain multi-dimensional nanoparticles (MDP). To further understand the activity of different rod-lamellar nanostructures of PALC and MDP induced by the OA leaching process, and also to prepare high-performance antibacterial materials, a series of nanocomposites based on silver nanoparticles (AgNPs) were prepared in this study, using PALC and MDP as the nanocarrier. TEM, FTIR, XRD, Zeta potential and other characterizations together proved that OA leaching of PALC in the range of 8–48 h (MDP-8 h, MDP-24 h, MDP-48 h) was the most beneficial for in-situ synthesis of monodispersed AgNPs. The antibacterial evaluation results showed that the growth of 99.30 %, 84.94 %, 60.72 %, 79.48 %, 87.78 % of E. coli, S.aureus, ESBL-E. coli, P. aeruginosa and MRSA (1.5 × 105 CFU/mL) were inhibited after treatment with 0.5 µg/mL of MDP-24 h/AgNPs, confirming its excellent and broad-spectrum antibacterial performance, which is mainly due to the most ideal natural multi-dimensional nanostructure of MDP after 24 h of OA leaching. In brief, a simple and efficient method was used in this study to realize the high-value application of natural multi-dimensional nanoclay and to prepare antibacterial composites with promising applications.