Biopolymers as intermediate layers for amoxicillin grafting on antibacterial surface

In this study, an antibiotic, amoxicillin (AMX) was grafted on titanium (Ti) surface through two different biocompatible polymers: polydopamine (PD) and silk fibroin (SF). The interaction of PD and SF with titanium surface and AMX was evaluated at the surface interface by testing the ability of the two polymers coatings to load and release amoxicillin from titanium dental implant surface. The biopolymers were easily deposited on Ti surface by self-polymerization (PD) and by electrodeposition (SF). This study is thematically focuses on surface and interface modifications and characterization. Surface was characterized in terms of morphology, hydrophilic character, roughness, and microhardness for the obtained biopolymer coatings grafted with AMX. The successful immobilization of AMX on Ti coated substrate was evidenced by spectral analysis. FTIR analysis revealed a stronger π-π interactions and hydrogen bonds between PD and AMX and a possible spontaneous conjugation of silk protein with AMX. Electrochemical tests (Tafel analysis, impedance spectroscopy and cyclic voltammetry) were used to highlight the electrochemical stability and the corrosion efficiency of the interface between modified surfaces and Fusayama simulated biofluid. SF coating leads to a better electrochemical stability and PD assure supplementary a better loading and slower release of AMX. The amoxicillin release in Fusayama simulated saliva was analysed for 192 h. The two coated samples were subjected to antibacterial tests, presenting an increased antibacterial effect for 8 days, suggesting a synergistic effect between antibiotic and biopolymer. Overall, the results showed that these two biopolymers can be successfully used as intermediate layer for antibiotics loading on dental implantable surfaces.