Anti-infection trauma devices with drug release and nonfouling surface modification.

ABSTRACT

OBJECTIVES: By coupling an antimicrobial release with a highly nonfouling betaine modification on titanium, this approach innovatively addresses the initial bacterial challenge and the longer term biofilm formation on trauma devices. METHODS: Titanium substrates were modified to obtain a polymer reservoir for chlorhexidine (CHX) and a polybetaine surface layer. The surface was characterized by infrared spectroscopy, scanning electron microscopy, laser confocal scanning microscopy, and a radiolabeled fibrinogen assay. The in vitro drug release profiles were measured using an ultraviolet-visible spectroscopy and a high-performance liquid chromatography. The efficacy to inhibit surface biofilm formation was determined by a bacterial adherence assay. The surface modification's bonding strength to the titanium substrate was measured, and its resistance to abrasion was tested ex vivo. Additionally, the biocompatibility was tested after ISO 10993 procedures. RESULTS: Titanium surfaces were successfully modified with a conformal and strongly bound polymer layer. No scratches were observed when inserting the modified titanium wires into porcine femur, and preservation of modification was confirmed by infrared spectroscopy. Controlled release of CHX was demonstrated for more than 8 weeks, and different formulations were tailored for different release rates. Greater than 3 log (99.9%) reductions in bacterial adherence were achieved after serum exposure. Additionally, the nonfouling properties were retained after several weeks of CHX release. Modified materials passed ISO 10993 testing for permanent implant devices. CONCLUSIONS: By innovatively addressing the initial bacterial challenge and longer term biofilm formation on trauma devices, this approach may be a superior solution to the current biofilm control technology.