The prevention of infections upon implantation of medical devices and materials, including, namely, urological catheters, represents a significant clinical challenge. A primary source of such infections is bacterial biofilms, which form on the device or material surface via the surface colonization of bacterial cells upon contamination. Despite considerable efforts to develop anti-biofilm materials and coatings, little progress has been made in inhibiting biofilm-related infections in catheters, placing an enormous burden on healthcare systems worldwide. The overall aim of this proposal is to develop a novel strategy to resist biofilm formation on catheter surfaces via inhibiting quorum sensing in surface-associated bacteria. This strategy will be investigated by covalently immobilizing the quorum quenching enzyme aminoacylase, which catalyzes the degradation of N-acyl amino acids, in polyurethane coatings. We hypothesize that the immobilization of aminoacylase in polyurethane coatings will facilitate the biocatalytic hydrolysis of quorum signals that induce the assembly of microbial consortia on surfaces. Aminoacylase will specifically be immobilized within polyurethane coatings via dispersion of the enzyme in an aqueous mixture of polyisocyanate and polyol prepolymers. Dispersion of the enzyme in the aqueous polymerization reaction facilitates covalent coupling of the enzyme to the polymer network via functional groups on the enzyme surface. Upon immobilization, the activity and stability of aminoacylase will be studied to understand how immobilization impacts enzyme function. Moreover, we will ascertain the inhibitory activity of the resulting coatings towards the formation of biofilms by Pseudomonas aeruginosa, which is prevalent in biofilm infections in catheters. Accordingly, the specific objectives of this research are to: 1) characterize the incorporation of aminoacylase in two-component waterborne polyurethane coatings via multipoint covalent immobilization, 2) determine the extent to which quorum sensing in P. aeruginosa by aminoacylase-containing coatings is inhibited, and 3) demonstrate the prevention of biofilm formation by P. aeruginosa by aminoacylase-containing coatings on model surfaces. We anticipate at the completion of this research to fully understand the relationship between immobilized aminoacylase activity and quorum quenching as well as biofilm inhibition by the coatings. Ultimately, this work will have considerable implications in reducing patient suffering and healthcare costs associated with urological catheter-related infections as well as infections from vascular catheters. More broadly, such coatings may also have utility in the prevention of infections on contact lenses, where biofilms are also prevalent, and on other implantable biomaterials and medical devices.
The overarching goal of this research is to develop a novel strategy to prevent biofilm formation on catheter surfaces, thereby reducing catheter-related infections. The proposed strategy is based on inhibiting signaling pathways involved in the assembly of surface-associated bacteria. This work will have considerable implications in reducing patient suffering and healthcare costs associated with catheter-related infections as well as infections from other indwelling materials.