Amphiphilic Quaternized Chitosan: Synthesis, Characterization, and Anti-Cariogenic Biofilm Property

Hydrophobized chitosan derivatives, hexyl chitosan (HCS), dodecyl chitosan (DCS), and phthaloyl chitosan (PhCS) of approximately 30 and 50% degree of substitution (%DS) reacted with glycidyltrimethylammonium chloride (GTMAC) to incorporate hydrophilic positively charged groups of N-[(2-hydroxyl-3-trimethylammonium)-propyl] and yielded amphiphilic quaternized chitosan derivatives. They can assemble into spherical nanoparticles with a hydrodynamic diameter of similar to 100-300 nm and positive zeta-potential values (+15 to +56). Their anti-biofilm efficacy was evaluated against the dental caries pathogen, Streptococcus mutans. Among all derivatives, the one having 30%DS of hexyl group and prepared by reacting with 1 mol equivalent of GTMAC (H30CS-GTMAC) showed the best performance in terms of its aqueous solubility, the lowest minimum inhibitory concentration (138 mu g/mL) and the minimum bactericidal concentration (275 mu g/mL) which are superior to the unmodified chitosan. Its equivalent anti-biofilm efficacy to that of chlorhexidine suggests that it can be a greener antibacterial agent for oral care formulations.