Effect of molecular dimension on gallery height, release kinetics and antibacterial activity of ZnAl layered double hydroxide (LDH) encapsulated with benzoate and its derivatives

This paper outlines the encapsulation of benzoate and its two derivatives i.e. para-hydroxybenzoic acid (p-BZOH) and 2-chloro-5-nitrobenzoic acid (BZCN) having antibacterial activity in between the interlayer distance of ZnAl layered double hydroxides to form an antibacterial composite material. The three reagents were successfully intercalated in between ZnAl LDH via anion-exchange mechanism. The intercalation was successfully evaluated by the increase in the basal spacing from X-ray diffraction, FTIR and thermogravimetry (TG-DTA) analysis. By variation of incoming reagents, the nature of interlayer arrangement, the tendency of binding, kinetics of release of the reagent from the inorganic lamella and bactericidal effect differ. The novel nano-composites demonstrated a distinctly enhanced bactericidal effect towards both gram positive (Staphylococcus aureus, MTCC 96) and gram negative (Escherichia coli, MTCC 739) bacterial strains having diverse rate of killing. Also the diffusion of the active molecules out of the nano-composites was found to be very slow and in a sustained manner in case of BZCN as compared to other two. Therefore these newly designed organic-inorganic fusions may offer a promising antimicrobial elucidation to the society.