On the enhanced antibacterial activity of plasma electrolytic oxidation (PEO) coatings that incorporate particles: A review

Biomaterials are substances of artificial or natural origin that are used to improve, treat, heal or replace the tissue or bone of a human or animal body. Due to the ever-increasing progress and the widespread use of biomaterials for various biomedical purposes, different methods are used to modify their surface characteristics. One of the problems facing biomaterials such as implants, prostheses, and stents is the presence of various bacteria that can cause adverse side effects such as infection, swelling, and tenderness. This raises the issue of their resistance to bacterial infection, a subject that needs to be thoroughly investigated. So far, a variety of methods have been developed to treat or coat biomaterials and make them resistant to bacterial infections. One of the most promising approaches is the plasma electrolytic oxidation (PEO) process. This process is not only successful in the formation of porous, hard, corrosion-resistant, wear-resistant, and biocompatible coatings but also can be easily manipulated to introduce antibacterial agents to the coatings structure. The addition of nano-or micro-sized particles in the electrolytes has been proven to not only modify the composition and structure of the PEO coatings, but also bring about a strong antibacterial activity. In light of recent advances in this field, the following review aims at discussing different aspects of particles addition in PEO electrolytes when the antibacterial activity is the main concern.