PhD Light Activated Anti-infective Biomaterials for Healthcare

Polymeric biomaterials, which are typically synthetic substances which can be introduced into body tissue as part of an implanted medical device or used to replace an organ or bodily function, are increasingly ubiquitous in healthcare. The introduction of biomaterials into the body, however, brings with it a risk of infection from microorganisms. This infection represents a major risk to patients and burden to the NHS requiring extended, complex treatments, which are frequently unsuccessful. With infection rates approaching 100% in some devices, there is an urgent unmet need to develop ways to prevent bacterial biofilms forming on the surface of medical devices.

Typically, infection involves initial attachment of bacteria to the surface of the biomaterial, followed by colonisation through subdivision and growth into a biofilm. This biofilm is highly resistant to treatment by antibiotics, and acts as a reservoir for further spread of infection in the body. This can lead to sepsis and death.

To effectively address the problem of biofilm development in biomaterials, this project has two key aims.

Firstly, we seek to control the nature of the polymer surface which is encountered by a bacterial cell. Using synthetic chemistry, we will develop new 'building blocks' for polymers which can be used to provide a coating to a current medical device material. By selectively tuning the chemistry of these units, we can engineer polymers which are inherently able to resist the attachment of bacteria. In practice, this involves polymer synthesis to fabricate our new candidate materials, then characterising their surface chemistry using a range of spectroscopic, microscopic and physical methods. We will then assess the ability of these materials to resist bacterial attachment by trying to grow biofilms of bacteria which typically cause infections.

Secondly, we seek to extend a recent finding from our laboratory which presents a new way to kill any bacteria which may still be able to attach to the polymer. This uses a combination of visible light and photosensitisers - a class of molecule which can use light to catalytically produce reactive oxygen, which is highly effective at killing bacteria. This is important as the approach does not allow the development of antimicrobial resistance, and has a long lived effect, which should allow it to be translated clinically for patients in the future.

In this strand, we will use synthetic chemistry and materials science to develop new methods to immobilise photosensitisers at the direct point of bacterial attachment - the polymer surface. We will tune the efficiency of this system to maximise production of reactive oxygen, and carry out a full chemical and physical characterisation of the light-induced processes and how effectively they kill bacteria.

Together, realising these aims will allow us to develop materials which may be incorporated into medical device surfaces such as endotracheal tubes, urinary catheters, or intraocular lenses, which would have wide impact for patients and medical device companies.