ENGINEERING BIOMATERIAL INTERFACES FOR MICROBIAL CONTROL

Since its inception as early as ancient Chinese placing bamboo pegs in place of missing teeth over 4,000 years ago, biomaterials have been an indispensable component of medical tools at human’s disposal. While early implants rely solely on the material properties themselves, modern devices have become much more than just materials. Topographic features, coatings, surface energy, and even embedded electronics have all added dimensions to the complexity of biomaterials and medical devices. Interaction between these materials and host cells and tissues, as well as microbes that can cause infections. Although well recognized for its significance, controlling biomaterial associated infections is challenging due to high level tolerance of attached bacteria to conventional antibiotics. The purpose of this PhD study is to design and engineer biomaterials for better microbial control, e.g., improving antifouling behavior and antibiotic treatment efficacy. To better understand how biomaterials interact with the human immune system to clear infections, we developed an assay to screen suitable implant topography for bacteria clearance by host macrophages. This led to the discovery of critical recessive pattern dimensions that attenuate phagocytosis of bacterial cells. In addition, a prototype antifouling catheter with active topography was engineered for testing in a rabbit model of catheter-associated urinary tract infection. This design was inspired by the cilia on human endothelial lining and was shown to have antifouling capabilities in vitro against uropathogenic E. coli biofilm formation. In addition to topographic features on biomaterials, this study also explored low-cost embedded electronics for microbial detection. Specifically, a novel LC sensor system was developed to detect bacterial growth on surfaces, reporting the fastest phenotypical antibiotic susceptibility to date. It has potential to be integrated with implantable medical devices. These findings and engineered devices will help shape the next generation of rationally engineered implants that can sense and respond to microbial adhesion, and thus prevent and treat related infections.