A Review on the Latest Developments of Conducting Polymer and Composite Coatings for Enhancing Biocompatibility and Corrosion Resistance of Metallic Biomedical Implants

The utilisation of metals and alloys in the biomedical field was and is still of immense importance for human life. Typically, the materials used for metallic biomedical applications, particularly those are implanted in vivo, provide appropriate mechanical and biological properties that allow them to accomplish the purpose for which they are used. Nonetheless, there are some inherent limitations impede the optimal use of these materials. One of the most crucial determinants is corrosion, which results in several other problems such as the formation of toxic substances that can not only cause necrosis of the cells attached to the implant, these toxins could also be carried by blood into body tissues and organs. This in turn leads to dire consequences on patient's life. Although a wide variety of approaches may be available to address the corrosion issue, it is alleged that coating these metals and alloys with polymers, especially the conductive ones, is among the best strategies in this regard. This review will highlight the latest developments in using conductive polymers including polypyrrole, polyaniline, polythiophene and their composites in order to enhance biocompatibility, mechanical properties and most importantly corrosion protection performance of metallic implants. The findings obtained from coating 316L stainless steel, titanium and magnesium alloys, which have been widely manipulated in biomedical field as long and short-term implants, will be evaluated.