Antimicrobial peptides and their application to combat implant-associated infections - opportunities and challenges

Despite minimally invasive surgeries and advancements in aseptic techniques, implant-associated infections are a significant complication in post-surgical implantation of medical devices. The standard practice of systemic antibiotic administration is often ineffective due to the development of bacterial antibiotic resistance, poor antibiotic penetration into biofilms, and low antibiotic bioavailability at the infected site. Infected implants are typically salvaged by tissue resection and antibacterial reinforcements during revision surgery. Towards this end, antimicrobial peptides (AMPs) have emerged as a promising alternative to traditional antibiotics to combat infections. Herein, a comprehensive overview of antimicrobial peptides, their structure and function, comparison with conventional antibiotics, antimicrobial properties, mechanisms of action of AMPs, and bacterial resistance to AMPs in relation to antibiotics are discussed. Furthermore, stimuli-responsive AMP delivery and contact killing via AMP coatings on implant surfaces are deliberated. We discuss various methods of AMP immobilization and coatings on implant materials through physico-chemical coating strategies. The review also addresses the clinical status and current limitations of AMP coatings such as proteolytic instability and potential cytotoxicity. Finally, we conclude with future directions to develop small, effective AMP mimetics and encapsulation of AMPs within nanocarriers to improve antimicrobial properties and design-controlled release systems for sustained antimicrobial activity.