Biocompatible and Bioactive Surface Modifications for Prolonged In Vivo Efficacy

Abstract

Generally, medical implants, regardless of their construction materials, will become coated in a layer of non-specific proteins mere seconds after implantation. This adsorbed layer activates an irrevocable host defense mechanism, known as the foreign body reaction, which ultimately results in the production of a fibrous avascular capsule that isolates the device from its target tissues, clogs the pores of membranes and sensors, and prevents drug release from a delivery vehicle. Many devices eventually fail because of their inability to effectively communicate with the surrounding tissues. It is becoming apparent that sub-cellular interactions at the biological-material interface have macroscopic outcomes. The success of the next generation of implants depends on overcoming limitations in biological communication by selective modification of device surfaces. This review focuses on recent advances in increased implant efficacy through selective surface modifications. Several approaches co-opt solutions found in the natural world to create a surface that mimics the properties of the cell membrane, thereby imparting a pseudo-biological character to synthetic materials. We begin with a short description of the foreign body reaction and then examine the biocompatible and bioactive device surface modification advances from the past five years that hold the potential of increased in vivo effectiveness.