Development of antibiotic-loaded silk fibroin/hyaluronic acid polyelectrolyte film coated CoCrMo alloy

Bacteria related infections are still a major problem for the implant materials. Such infections have occurred in nearly 3% of hip and knee replacements resulting in failure of device. There are two main approaches for inhibiting the bacterial adhesion to the surface. These involve bactericidal substances and anti-adhesive coatings. In this study, the efficiency of antibiotic-loaded silk fibroin/hyaluronic acid polyelectrolyte film coated CoCrMo alloy, prepared by means of complex coacervate and layer by layer techniques, was investigated. A medical grade CoCrMo was coated with variable number of silk fibroin/hyaluronic acid up to 14 layers at room temperature. The morphological evolution during and after formation of the crystal structure on the coating layer, the resulting surface roughness, and the corresponding alterations in the coating layer thicknesses were thoroughly studied using various analytical techniques, including attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). As a result, only 10 layers of silk fibroin/hyaluronic acid complex coacervate films were found to convey the general characteristics of the mixture of silk I and II, while layer by layer coated samples exhibited the mixture of silk I and II. Moreover, regardless of the preparation method applied, the surface roughness and the coating layer thicknesses were determined to increase with the increasing number of layers. The antibacterial test results suggested that the samples loaded with antibiotic successfully induced a bactericidal resistance against Staphylococcus aureus bacteria.