Enhancing the antibacterial properties of chitosan to tackle dental biofilms

Dental caries are largely preventable yet they remain a serious problem that rises to a status of an endemic disease in developing countries. Finding novel antibacterial agents from nature with low toxicity, good stability in the oral cavity, easily available and at low production cost is therefore very topical today. Fluoride is commonly used agent utilised for the prevention of dental carries in various formulations, however it can be toxic upon ingestion in high doses. Chitosan is a natural polysaccharide known for its antimicrobial activity, low toxicity, low cost, high availability, biocompatibility and biodegradability that can lead to promising antibacterial materials. We aim to develop novel chitosan-based antimicrobial polymers for the prevention and the treatment of periodontitis. N-lysine-chitosan(CS3H-Lys) has been synthesized by reacting low molecular weight chitosan (CS3H) with Fmoc-Lys(Fmoc)-OH, in order to maintain the positive charge of the polymer at physiological pH. Fluoride was incorporated using dialysis against sodium fluoride to potentiate the polymers antimicrobial activity and localise the fluoride at the site of action reducing its unwanted toxicity. The modified polymers were examined in vitro to determine their ability to prevent  biofilm formation of cariogenic bacteria and to inhibit the acid demineralisation of the tooth.

CS3H-Lys was shown to be active against the Streptococcus mutans and Staphylococcus aureus commonly found cariogenic agents in dental caries. CS3H-Lys solubility was enhanced by preparation of the fluoride salt which further also enhanced its antimicrobial activity. CS3H-Lys was also shown to protect the hydroxyapatite layer of teeth from acid attack.    

We have successfully synthesised and characterised a novel fluorinated chitosan derivative with promising properties for use in the prevention and treatment of periodontitis. We plan to develop a novel cost-effective and safe formulation for better oral healthcare worldwide.