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

导尿管相关性尿路感染(CAUTIs)和结垢严重影响人类的健康和医疗费用。到目前为止，只有几种类型的抗菌涂层导管进入临床使用，包括呋喃甲醛浸渍导管、银合金水凝胶涂层导管和聚四氟乙烯涂层导管。临床试验表明，这些涂层导管在CAUTIs或结痂形成方面的减少并不显著。众所周知，纳米二氧化钛和纳米银都具有杀菌性能。然而，直径小于200 nm的银纳米粒子容易自发聚集，在空气、水或阳光中的稳定性不够好，不能长期使用，这降低了它们的抗菌性能。为了解决这些问题，人们开发了一系列不同的无团聚的银-二氧化钛复合纳米颗粒。研究表明，在光照和黑暗条件下，核壳结构的银@二氧化钛纳米粒子(包裹一层薄层二氧化钛的银纳米粒子)和球形的银/二氧化钛纳米粒子(包覆银纳米粒子的二氧化钛纳米粒子)均表现出协同杀菌活性，且杀菌作用持续时间较长。Ag@TiO2光催化剂或Ag/TiO2光催化复合材料中的银纳米粒子能够激活可见光激发的TiO2光催化活性，并能显著提高细菌的光催化灭活性能。在这项计划中，两种不同类型的银@二氧化钛-聚四氟乙烯涂层和银/二氧化钛-聚四氟乙烯涂层导管将通过凝胶技术被开发出来。这两种新型涂层结合了银@二氧化钛和银/二氧化钛纳米颗粒的优异抗菌性能和聚四氟乙烯纳米颗粒的不粘性。将计算和测量选定的细菌与尿液中涂层导管之间的相互作用，以找出涂层的最佳表面条件。使用模拟人体膀胱活体环境的膀胱模型来评估涂层全长导尿管在尿液中的抗菌和防结块性能，并与现有的银水凝胶涂层导管、聚四氟乙烯涂层导管和未涂层硅胶导管进行比较。还将进行涂层导管的细胞毒性测试。项目完成后，我们将与当地医院和一家导管制造商合作进行临床试验。

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.