Metal implants and polymeric devices in the clinical treatment of orthopedic tissue injuries are increasingly coated with bioactive biomaterials derived from natural substances to induce desirable biological effects. This study compares potential coating materials for titanium implants. These coating materials are chitosan membranes prepared from starting materials with different degree of deacetylation (DD). We were able to show that higher DD chitosan membranes are associated with increased surface roughness, increased fibronectin adsorption, and improved bioactivity. We also managed to successfully prepare membranes from chitosan with a low DD and established crosslinking protocols to enable long-term cultures with sustained cell attachment.

Chitosan is one of the most promising natural substances used in biomaterials research, yet numerous challenges remain prior to the successful translation into the clinics. We also need to establish certain standards on how to publish reports on the use of chitosan, which should at the very least include the degree of deacetylation, the molecular weight, the source, detailed processing parameters, and potential contaminants. The effect of endotoxin contamination on biomaterial performance in vitro should also not be underestimated, as even minute amounts of endotoxins can elicit strong inflammatory reactions that might overrule any biological effect of the biomaterial itself.