Light-activated antimicrobial polymers for the prevention of catheter-associated infections

住院患者往往病情严重，不能通过口服或注射给药，这些药物必须通过直接连接到静脉或动脉的细管给药。此外，他们经常无法排尿，因此需要直接将尿管插入膀胱，以便尿液可以通过尿管排入收集袋。这种导管被称为导尿管，在住院患者中被广泛使用。导尿管的主要问题之一是微生物(通常来自患者的皮肤)不可避免地粘在导尿管的表面，在那里它们生长形成一种结构(称为生物膜)，该结构由数百万细菌组成，周围有一种凝胶状的材料。在这些生物膜内，微生物受到身体防御系统和抗生素的保护。因此，一旦导管上形成生物膜，就很难去除它们，最终会导致感染，可能会导致患者死亡。为了防止患者死于这种感染，经常需要拔掉导尿管并插入新的导尿管，这对患者来说非常不舒服，对医务人员来说也很耗时。在这个项目中，我们打算开发一种新的方法来预防这种感染--这将基于使用光激活的抗菌剂(也称为光敏剂)。光敏剂是一种化学物质，在普通光线下对微生物没有影响，但会被特定波长的光激活--这通常是由小型激光提供的。这种被激活的光敏剂产生的物质可以杀死任何存在的微生物。我们打算在用于制造导管的材料中添加光敏剂，并进行实验，以找出这种材料在激光照射下是否可以阻止微生物附着在它上面，或者实际上杀死它们。一旦我们找出了使用光敏剂的最佳浓度以及需要多少光，我们就会进行更复杂的实验，其中我们将使用实验室模型的导管。如果我们的光激活材料可以防止微生物附着或在实验室模型中杀死它们，那么它们很可能对患者也有效。用于激活光敏器的光源将是一种低功率激光器，类似于教师和讲师使用的激光指示器，因此使用起来很方便--能够行走的患者很容易携带它。来自激光的光将穿过光纤，光纤将连接到导管。我们认为，这种使用光激活抗菌剂的方法是一种令人兴奋的、新颖的预防与导管相关的感染的方法，将对患者产生巨大的好处。

Patients in hospital are often too ill to be given drugs by mouth or by injection and these have to be administered through a fine tube connected directly to a vein or artery. Also, they are often unable to urinate and so need a tube inserted directly into their bladder so that urine can drain through this into a collecting bag. Such tubes are known as catheters and are very widely used by hospitalised patients. One of the main problems with catheters is that microbes (usually from the patient's skin) inevitably stick to their surfaces where they grow to form a structure (known as a biofilm) consisting of millions of bacteria surrounded by a jelly-like material. Inside these biofilms, the microbes are protected from the body's defence systems as well as from antibiotics. Therefore, once biofilms have formed on a catheter they are very difficult to remove and they eventually cause an infection which can kill the patient. To prevent the patient dying from such an infection, the catheter often has to be removed and a new one inserted which is very unpleasant for the patient and time-consuming for medical staff. In this project we intend developing a new way of preventing such infections - this will be based on the use of light-activated antimicrobial agents (also known as photosensitisers). A photosensitiser is a chemical that has no effect on microbes in ordinary light but is 'activated' by light of a certain wavelength - this is usually provided by a small laser. The activated photosensitiser produces substances that can kill any microbes present. We intend adding a photosensitiser to the material used to make catheters and carrying out experiments to find out whether this material, when illuminated with laser light, can either stop microbes sticking to it or else actually kill them. Once we have found out the best concentration of photosensitiser to use and how much light is necessary, we will then carry out more complicated experiments in which we will use laboratory models of catheters. If our light-activated material can prevent microbes adhering or can kill them in laboratory models, then they are likely to be effective also in patients. The light source used to activate the photosensitiser would be a low-power laser similar to the laser pointers used by teachers and lecturers so making it convenient to use - it could easily be carried around by patients who are able to walk. Light from the laser would pass through optical fibres which would be connected to the catheter. We think that this approach using light-activated antimicrobial agents is an exciting, novel way of preventing infections associated with catheters and will be of great benefit to patients.