Functional behavior of chitosan/gelatin/silica-gentamicin coatings by electrophoretic deposition on surgical grade stainless steel

Metals are used in several orthopedic applications as fixation elements for the stabilization of fractures or as prostheses. One of the most common orthopedic biomaterials in many developing countries is surgical grade stainless steel (SS). However, its use as permanent implant in orthopedic surgery is conditioned due to its limited corrosion resistance in physiological media, lack of osseointegration, and absence of antibacterial effect. The aim of this work is to generate a degradable coating with antibacterial properties for stainless steel to be used in implants/medical devices. The coating is composed of a biopolymer/silica-gentamicin nanoparticles composite obtained by electrophoretic deposition (EPD) on surgical grade stainless steel plates. The coating surface was characterized by microscopic examination, and in vitro performance was evaluated after immersion in phosphate-buffered saline (PBS) solution, simulated body fluid (SBF), and cell culture medium, to analyze coating degradation, antibiotics release, cell attachment (ST-2 stromal cells), and antibacterial (Escherichia coli and Staphylococcus aureus) properties. EPD coatings were uniform and covered homogeneously the surface of the SS substrate. Also the distribution of silica-gentamicin nanoparticles was homogeneous on the coated area. The degradation of the chitosan-gelatin coatings was evident after 7 days of immersion. The gentamicin release led to excellent antibacterial behavior at 24 h, meanwhile the cell proliferation (at 7 days culture) was not inhibited. The results show that the coating system exhibits promising behavior which could contribute to prevent hospital infections at early implantation times.