Metallic biomaterials are widely used for orthopedic and dental implant applications because of their superior mechanical strength, biocompatibility, and corrosion-resistant properties. The implantation of metallic devices in human body is always accompanied by corrosion phenomena due to the harsh and corrosive nature of the physiological environment. Metals may undergo different types of corrosion processes such as uniform, pitting, galvanic, and microbially-induced corrosion (MIC). Corrosion can adversely affect the mechanical integrity, functionality, and durability of implants and is a prime factor governing their biocompatibility. The principal paradigm of biocompatibility of metallic biomaterials has been “the more corrosion resistant, the more biocompatible.”. Therefore, protection of metallic implants against corrosion is very crucial. The application of protective coatings is a well-established strategy for separating metals from external aggressive environments. Among different types of protective coatings, polymeric coatings have been recognized as the most effective method to mitigate the corrosion of metallic substrates without changing their bulk properties, while providing them with other functionalities such as enhanced biocompatibility and cellular responses, ability to load small molecules, and antibacterial properties. This dissertation is focused on the development of multifunctional polymeric coatings to enhance the corrosion resistance properties of different types of metallic biomedical implants. The fabricated coatings were fully characterized through various physicochemical, electrochemical, and biological techniques to evaluate their potential as protective coating materials for bio-implant applications. In the first application, a polymeric coating based on polycaprolactone and lawsone, a natural plant extract obtained from Henna leaves, was fabricated on AZ31 Mg alloy to enhance its corrosion resistance and cytocompatibility for temporary orthopedic implant application. Incorporation of Lawsone provided the PCL coating with both corrosion inhibition properties and antibacterial activity. In the second application, a composite polymeric coating based on silk fibroin and cellulose nanocrystal was fabricated on AZ31 Mg alloy to enhance its corrosion resistance and biocompatibility for biodegradable bone implant application. In the third application, MIC of stainless steel was evaluated by using Streptococcus mutans as model microorganism for dental implant application. All the coatings were fully characterized through various physicochemical, electrochemical, and biological techniques to evaluate their potential as protective coating materials for bio-implant applications.
