Effect of different HDTMA loading on silver modified kaolinite on its antibacterial activity

Abstract

A synergistic combination of organic and inorganic materials as a hybrid antibacterial agent aiming to combine two or more antibacterial compounds in a carrier system has been developed. This research aimed to study the physicochemical properties of silver loaded kaolinite attached with different amounts of cationic surfactant hexadecyltrimethylammonium (HDTMA) and its effect on Gram-positive and Gram-negative bacteria. Kaolinite was initially modified with silver ion and later, with different HDTMA concentrations (50, 75, and 100% of Cation Exchange Capacity (CEC) of the kaolinite). The materials were characterized using X-ray diffraction, Fourier transforms infrared spectroscopy and field emission scanning electron microscope equipped with energy dispersive X-ray analyzer. Antibacterial activity was evaluated using disc diffusion technique against Escherichia coli and Staphylococcus aureus. Characterization results showed that kaolinite was successfully modified with silver ion and HDTMA. For the antibacterial assay, S. aureus was more susceptible than E. coli due to differences in their peptidoglycan structure, whereas, surfactant-modified silver kaolinite was more effective in inhibiting bacterial growth than silver kaolinite. However, the different concentrations of HDTMA did not alter the existing inhibitory effects against these bacteria. Thus, the low concentration of HDTMA loaded on silver-kaolinite is suitable to be used as an antibacterial agent.