Development of Calcium Carbonate Double-Coated with Chitosan-Adipic Acid as a Promising Antibacterial Filler

Abstract

The aim of the present work was to investigate a new use of chitosan in the modification of calcium carbonate (CaCO 3 ) particles in order to confer specific antibacterial functionality to the particles. Adipic acid was used to introduce carboxyl groups onto the surface of CaCO 3 particles. CaCO 3 particles double-coated with chitosan-adipic acid (abbreviated as CAC) were prepared through the ionic interaction between the 2 site amino group of chitosan and the carboxyl group of adipic acid. The structure of CAC was characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The zeta potential and contact angle of CAC were studied to evaluate particle interfacial properties. FTIR and TGA analyses showed that chitosan and adipic acid on CAC were combined through electrostatic interactions. When the chitosan concentration was more than 5%, the surface of the CaCO 3 particles were coated completely. When chitosan was applied at a 9% concentration to make CAC, the zeta potential increased from -27.58 mV for unmodified particles to +13.11 mV for CAC due to the increased positive charge from chitosan. In a similar way, the specific surface area increased from 2.846 m 2 /g to 4.709 m 2 /g, the average particle size decreased from 11.21 μm to 7.49 μm, and the contact angle increased from 0°to 87°. CAC had antibacterial capacity when evaluated with E. coli and S. aureus. The approach in this study provides a method for fabricating chitosan-adipic acid-modified CaCO 3 particles, an antibacterial filler for potential applications.