Influence of Surface Properties of New Biomaterials for Catheters on Bacterial Adhesion in Urine

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Catheter-associated urinary tract infection (CAUTIs) and encrustation have a severe impact on human health and health care costs. To date only a few types of antimicrobial coated catheters have come into clinical use, including a nitrofural-impregnated catheter, a silver alloy-hydrogel coated catheter, and a PTFE-coated catheter. Clinical trials show that these coated catheters give only an insignificant reduction in CAUTIs or encrustation formation. It is well known that both TiO2 and Ag nanoparticles exhibit bactericidal properties. However Ag nanoparticles with diameters less than 200 nm tend to aggregate spontaneously, and their stability in air, water or sunlight is not good enough for long-term application, which decreases their antibacterial performance. To solve these problems, a range of different Ag-TiO2 composite nanoparticles have been developed without aggregation. It has been demonstrated that both core-shell Ag@TiO2 nanoparticles (Ag nanoparticles coated with a thin shell of TiO2) and spherical Ag/TiO2 nanoparticles (TiO2 nanoparticles coated with Ag nanoparticles) exhibit synergistic bactericidal activities with long lasting action period in both light and dark conditions, compared with Ag and TiO2 nanoparticles. The Ag nanoparticles in Ag@TiO2 or Ag/TiO2 nanocomposites enable to active visible light excitation of TiO2, and can highly improve photocatalytic inactivation of bacteria. In this proposal two different types of Ag@TiO2-PTFE coated and Ag/TiO2-PTFE coated catheters will be developed by a so-gel technique. The two new types of coatings combine the excellent antibacterial properties of Ag@TiO2 and Ag/TiO2 nanoparticles and the non-stick properties of PTFE nanoparticles. The interactions between selected bacteria and the coated catheters in urine will be calculated and measured in order to find out optimum surface conditions of the coatings. The anti-bacterial and anti-encrustation performance of the coated full-length catheters in urine will be evaluated using bladder models that mimic in vivo environments of the human bladder for a catheter, and compared with existing silver-hydrogel coated catheter, PTFE coated catheter and uncoated silicone catheter. The cytotoxicity assays of the coated catheters will also be performed. After the project we will collaborate with local hospitals and a catheter manufacture to undertake clinical trials.