Preparation and characterization of chlorhexidine modified zinc-kaolinite and its antibacterial activity against bacteria isolated from water vending machine

Abstract

Access to the portable drinking water is of paramount importance and remains major challenge globally. Water vending machine (WVM) could supplies drinking water to the community but the bacterial growth in WVM is of great health risk requires urgent attention. Chlorhexidine zinc-modified kaolinite (C-Zn-Kao-t1) was prepared, characterized and studied to inhibit the growth of isolated bacteria from WVM. The material was prepared by attaching chlorhexidine (0.5âmmol/L) on Zn-loaded kaolinite in which the loading capacity of Zn on the kaolinite (Kao-t1) satisfied 50% of cation exchange capacity of the kaolinite. The materials were characterized using X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, energy dispersive X-ray and dispersion behaviour analysis. The C-Zn-Kao-t1 did not cause any structural changes on the original structure and morphology of the kaolinite. The antibacterial activity of the materials was studied using disc diffusion technique (DDT) and minimum inhibition concentration (MIC) against bacteria isolated from WVM which are Stenetrophomonas maltophilia and Bacillus cereus as well Escherichia coli ATCC 11229 as a comparison. Based on these antibacterial assays, C-Zn-Kao-t1 sample has the highest DDT and the lowest MIC values against all bacteria (accept the MIC value for E. coli) showing its excellent antibacterial activity against bacteria isolated from WVM. Further test on cytotoxicity towards human fibroblast cells in vitro showed that 0.5âmg of the C-Zn-Kao-t1 is cytocompatible towards HSF 1184 cells. This concludes that chlorhexidine modified zinc-kaolinite are not cytotoxic and can be embedded safely in WVM in preventing bacteria contamination.