Cytotoxic effects and biocompatibility of antimicrobial materials

The rising demand for medical implants for ageing populations and ongoing advancements in medical technology continue to drive the use of implantable devices. Higher implant usage has a consequent increased incidence of implantrelated infections, and associated prolonged patient care, pain and loss of limb and other organ function. Numerous antibacterial surfaces have been designed that prevent the onset of biofi lm formation, thus reducing or preventing implant-associated infections through inhibiting bacterial adhesion or by killing the organisms that successfully attach to the surface of the implant. Other surfaces have been designed to stimulate a local immune response, promoting the natural clearing of the invading pathogen. The desired antibacterial effects are typically achieved by modulating the surface chemistry and morphology of the implant material, by means of the controlled release of pharmacological agents and bioactive compounds from the surface of the material, or by a combination of both processes. An important issue for any type of antibacterial surface modifi cation lies in balancing the non-fouling, bacteriostatic or bactericidal effects against local and systemic biocompatibility. In this chapter, we will fi rst describe the concept of biocompatibility and its evolution, from devices that do not evoke a negative host response to those that actively drive host regeneration. We will then review the challenges associated with merging the need for an implant material to withstand a bacterial load with those associated with supporting function restoration and tissue healing.