Antibacterial PHAs coating for titanium implants

Biomaterial-associated infection is a serious complication of modern implantation surgery. Thus, the improvement of implant surfaces is required to avoid the first stage for biofilm formation, bacterial adhesion. The current research addresses this issue by developing drug delivery systems (DDS) consisting of antibiotic-loaded polyhydroxyalkanoates (PHAs) coatings on titanium implants. Dip-coating technique was used to achieve optimal coatings with biodegradable biopolyesters, polyhydroxybutyrate (PHB) and its copolymer, polyhydroxybutyrate-co-hydroxyvalerate (PHBV). The coatings were completely characterized (wettability, topography, thickness and roughness), and studies of drug delivery, toxicity, antibacterial effect, and cell adhesion were performed. For both of biopolymers, surfaces were partially covered with 1 and 3 immersions, while with 6, they were completely covered. Although both antibiotic-loaded biopolymer coatings assure the protection against bacteria populations, PHBV coatings are closer to the desired release profile; its faster degradation provides for a greater and more stable drug release for a given period of time compared to PHB coatings. The use of coatings with different drug concentration per layer results in more controlled and homogeneous releases. The DDS designed not only assure to avoid the first stage of bacterial adhesion, but also their proliferation and biofilm formation, since the coatings degrade with time under physiological conditions, guaranteeing a prolonged drug release.