Polymer coatings on magnesium‐based implants for orthopedic applications

Abstract

Nowadays, the need for bio‐implants, which can gradually degrade after fulfilling the therapeutic tasks is continuously increasing. Under such situation, magnesium (Mg) and its alloys have been proposed and intensively studied as the new‐generation medical implants due to their favorable biodegradability and biocompatibility. However, their swift corrosion in physiological environments can always cause an early fracture and further the surgical failure, greatly hindering their broad applications. Therefore, great efforts have been made to alter the degradation behaviors of Mg‐based implants. Biodegradable polymeric surface coatings have been revealed to be a straightforward and effective strategy for retarding the fast degradation and improving the bioactivity of Mg and its alloys. This article reviews the recent progress of polymer‐based coatings on Mg substrates, regarding the coating strategies, coating properties, and their performance in corrosive protection and biocompatibility promotion via in vitro as well as some in vivo models. The specific pros and cons of different polymeric coatings are also discussed. Finally, we put forward some perspectives on the future direction of polymeric coatings on biomedical Mg‐based implants to better adapt to clinical trials.

Progress in bioactive surface coatings on biodegradable Mg alloys: A critical review towards clinical translation

“…The physical, chemical, and mechanical properties of PLGA can be tailored by altering LA/GA ratio [ 297 ]. PLGA coatings are widely recognized for corrosion resistance and drug delivery applications [ 298 , 299 ]. The coating structure shown in Fig.…”

Natural Coatings and Surface Modifications on Magnesium Alloys for Biomedical Applications

“…Natural polymers usually contain biofunctional molecules that guarantee bioactivity [ 57 ] and non-immunogenic properties [ 58 ]. Another advantage of natural coatings is the ability to add functional properties to the implant surface, adapt the composition and structure of the coating [ 12 ], serve as templates for cell attachment and growth, and foment cellular responses; they have been utilized in biomedical fields (e.g., soft tissue engineering) for a long period [ 10 ]. Modified polymeric coatings can act as host reservoirs for corrosion inhibitors and can provide more effective active corrosion protection with self-healing properties [ 59 ].…”

“…In general, debris particles inhibit direct prosthesis–bone contact; cannot be easily phagocytosed, causing an inflammatory response; and are more susceptible to microbial colonization [ 8 , 9 ]. In this sense, an implanted device must retain its mechanical integrity until the bone tissue is recovered, and then gradually dissolve to be replaced by the osteogenic tissue [ 10 ].…”

“…To maintain the ideal degradation behavior of Mg, surface coatings have become one of the preferred strategies to provide acceptable control. Coatings can contribute to retarding corrosion and isolating the material from corrosive fluids [ 10 ]. Through modification of the implant surface by varying topography and coatings, it is possible to enhance the osseointegration [ 7 , 28 ].…”

“…There are two large groups of polymeric coatings: synthetic and natural polymers. Natural polymers present advantages such as their excellent biocompatibility due to their biomimetic nature, as well as their biological activity [ 10 , 19 , 31 ].…”