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

医院里的病人往往病得太重，不能口服或注射药物，这些药物必须通过一根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，因此需要将一根管子直接插入他们的膀胱，这样尿液就可以通过它流入一个收集袋。这种管子被称为导尿管，被住院病人广泛使用。导管的主要问题之一是微生物（通常来自患者的皮肤）不可避免地粘在导管表面，在那里它们生长形成一个结构（称为生物膜），由数百万细菌组成，周围是一种果冻状的物质。在这些生物膜内，微生物受到人体防御系统和抗生素的保护。因此，一旦生物膜在导管上形成，它们就很难去除，最终会导致感染，从而导致患者死亡。为了防止患者死于这种感染，通常必须拔掉导管并插入新的导管，这对患者来说是非常不愉快的，对医务人员来说也是非常耗时的。在这个项目中，我们打算开发一种预防这种感染的新方法——这将基于使用光活化抗菌剂（也称为光敏剂）。光敏剂是一种化学物质，它在普通光线下对微生物没有影响，但被特定波长的光“激活”——这种光通常由小型激光器提供。活化的光敏剂产生的物质可以杀死任何存在的微生物。我们打算在制造导管的材料中加入光敏剂，并进行实验，看看这种材料在激光照射下是否能阻止微生物附着在上面，或者杀死它们。一旦我们发现了使用光敏剂的最佳浓度和需要多少光，我们就会进行更复杂的实验，我们将使用实验室的导管模型。如果我们的光激活材料可以在实验室模型中阻止微生物粘附或杀死它们，那么它们可能对患者也有效。用于激活光敏剂的光源将是一种低功率激光，类似于教师和讲师使用的激光笔，因此使用起来很方便——能够行走的患者可以轻松携带。激光发出的光将通过连接到导管上的光纤。我们认为这种使用光活化抗菌剂的方法是一种令人兴奋的，预防导管相关感染的新方法，将对患者有很大的好处。

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.