Antibacterial coating based on lanthanum-doped nanobioactive glass/chitosan composite of metal implant for orthopedic applications

Abstract

Although bio-metallic alloys are commonly used as prostheses due to their unique mechanical properties and durability, they are often bioinert and lack antibacterial properties. Coating of metallic implants by composite materials provides mechanical strength, bioactivity and enhances antibacterial properties. In this study, chitosan and chitosan/La-doped nanobioactive glass (LBG) composite were synthesized for coating of 316 L stainless steel using the electrophoretic deposition technique. Thermal, structural and compositional properties of the synthesized glass were studied. Also, microstructure, adhesion strength, wetting, and in-vitro bioactivity of the deposited coatings were evaluated. Moreover, cytotoxicity of the coatings was investigated against normal skin cells. Hemolytic activity of coating was also measured to investigate coating biocompatibility with the hematic system. Furthermore, the deposited coatings were functionalized with antibacterial drug (gentamicin), where drug’s release profile and its kinetic were studied. The antibacterial activity of the functionalized coatings were determined as well. The obtained results showed that the deposited coatings presented good adhesion strengths (1.67 MPa and 0.80 MPa for chitosan and composite coating). The wettability of both coatings enhanced, contact angles are 33°, and 56° for Chit@SS, and LBG/Chit@SS, respectively, compared to SS, 77°. According to the obtained hemolysis values of coatings (less than 10%), they were considered biocompatible materials. As well as, the coatings formed apatite-like crystals on its surface after immersion in SBF, also they didn’t show a cytotoxic effect for normal skin cells. Gentamicin drug was released in a sustained manner by Fickian diffusion mechanism. Also, drug/coating containing LBG showed a higher antibacterial effect than that of chitosan coating. These findings indicated that the prepared composite coating of Lanthanum-doped bioactive glass incorporated with chitosan can be used to avoid bacterial infection and enhance bone healing in orthopedic and dental applications.