How to improve the resistance of bioactive implant coating?

Objectives: Peri-implant bacterial infections are the main cause of complications in dentistry. Furthermore, current implant devices do not prevent such infections. The coating of antibacterial molecules such as chitosan on the implant surface would bring bioactive properties. In this context, two objectives have to be achieved: (i) establish evidence of the attachment of chitosan onto a titanium substrate and (ii) study how the biopolymer will be maintained on titanium after immersion in saliva.
Methods: Polymer binding on the substrate is achieved by covalent link using a coupling agent. Currently, functionalization of the pre-activated titanium based surface (Ta6V) is performed using triethoxy-silylpropylsuccinic anhydride (TESPSA) as a coupling agent, which forms a stable double amide bond with chitosan.
Results: FTIR and XPS analyses confirm the presence of chitosan on the titanium surface. This coating shows high scratch resistance and is strongly adhesive to the substrate. These mechanical properties are consistent with an application in implantology. In addition, the resistance of the coating under acid pH solutions (pH 5 and pH 3) is also confirmed still using surface analyses. Moreover, the kinetics of chitosan coating release in acidic aqueous solutions was assessed by colorimetric assays.
Conclusions: Surface functionalization using the TESPSA/chitosan coupling method is noncytotoxic and stable even in drastic environments as found in oral cavity, thus making it a valuable candidate as a bioactive bacteriostatic coating for clinical implantology applications.