Phyto-mediated synthesis of ZnO/attapulgite nanocomposites using C. limon peel extract for enhancing the resistance against multidrug-resistant bacteria and fungi

Abstract

ZnO have great potential in combating multidrug-resistant (MDR) bacteria, however, green synthesis and activity regulation still face challenges. In this study, we designed a green bioinspired method mediated by C. limon peel extract to synthesise a series of attapulgite (APT) supported ZnO nanocomposites for enhancing the resistance against MDR pathogenic bacterial and fungal, in which the structure and morphology of ZnO was regulated by APT inducing heterogeneous nucleation of ZnO, thus enhancing the antibacterial activity of the nanocomposites. XRD and TEM analysis demonstrated that ZnO/APT with a unique peg-top-like morphology and well-defined crystal structure was successfully synthesized via the regulation of Zn²⁺ ions concentration. XPS results confirmed that the oxygen vacancy increased significantly compared with the pure ZnO (has a cubic shape) due to the structural modulation of ZnO induced by APT. The obtained ZnO/APT nanocomposites exhibited excellent biocompatibility and enhanced antibacterial efficacy with a complete inhibition at a concentration of 0.125 mg/mL for MRSA, a high inhibitory rate of 94.68 ± 1.43 % at a concentration of 0.5 mg/mL for ESBLs-E. coli, and the antifungal rate against C. albicans was found to be 95.59 ± 1.08 % at a concentration of 0.25 mg/mL. In addition, the ZnO/APT had a good hemostatic effect and enhanced biocompatibility compared to pure ZnO. The study provides a green way to design efficient ZnO antibacterial nanomaterials with remarkable antimicrobial efficacy and lower cytotoxicity, and the ZnO/APT nanocomposite is potential for clinical applications.