Polymeric Coatings and Features of the Preliminary Surface Treatment of Biodegradable Magnesium Alloys: A Review

Magnesium-based biodegradable alloys are a promising material for developing self-dissolving surgical implants. Coating their surface is one way to give medical products made of magnesium alloys the necessary corrosion characteristics, as well as increase affinity for bone and accelerate the healing process, by introducing medicines and nutrients into the coating. For magnesium alloys, oxide coatings obtained by oxidizing magnesium or applying oxides of other metals, as well as metal, ceramic, and polymer coatings, are used. In this review, polymer coatings, primarily their effect on the corrosion properties of the material, as well as the features of surface preparation of magnesium alloys before their application, have been considered. Information about the properties of coatings made from various synthetic (polylactide, polycaprolactone, polydopamine) and natural (chitosan) polymers has been provided. Attention to various types of surface treatment, such as mechanical grinding, chemical etching, fluorination, and alkalization, has been paid. For a few polymer coatings, the results of in vitro (on cell cultures) and in vivo (on animals) biocompatibility studies have been presented. Surface pretreatment has been shown to affect greatly such characteristics as coating adhesion and material corrosion resistance.