The Design and Engineering of Antimicrobial and Antifouling Surfaces

The prevention of adhesion of bacteria on surfaces of materials is of crucial importance in diverse fields such as medical devices, health care, hospital and dental surgery equipment, textiles, ship hull fouling and water purification systems. Once adhered on a solid surface, bacteria form colonies and subsequently biofilms that can develop into pathogenic infections.  Various strategies can be adopted to control microbial biofilm growth on solid surfaces. Failure to tackle antimicrobial resistance is estimated to cost an extra 10 million deaths per year and £64 trillion worldwide by 2050. The primary way to circumvent this is to develop new therapeutics and management strategies to repel microbial adhesion or kill any microbes via a contact killing or biocide leaching approach.

Nitric oxide releasing surfaces 

Successful treatment of a chronic wounds depends on identifying and treating factors that impede the healing process. It has recently been recognised that bacteria that are found in chronic wounds reside in communities called biofilms which contribute to infection and delayed healing. Therefore, standard wound management becomes more complex and new solutions need to be biofilm-targeted. Nitric Oxide (NO) is an effective therapeutic for chronic wound healing as it has been proven as a potent anti-biofilm agent.  The mode of action of NO is different to conventional antibiotics and as such will not contribute to AMR.  The aim of this project is to develop a platform to release NO from by tethering compounds containing caged NO reservoirs which are able to release the therapeutic in a controlled and sustained manner.

Non-fouling surfaces (PEG, Hyaluronic Acid)

Polymer brush-coatings are currently considered as promising, as these coatings reduce the adhesion of bacteria by orders of magnitude. The term “polymer brush” refers to a system where by chains of polymer molecules are attached by one end or a few anchor points to a surface or interface, such that the graft density of the polymer is high enough that the surface attached chains become crowded and are stretched away from the surface.  The project involves gaining fundamental knowledge of the structure and properties of these polymer brushes as well as investigating their efficacy for antimicrobial applications.

Antimicrobial peptide contact killing surfaces

Antimicrobial peptides (AMPs) are produced by all complex organisms as well as some microbes as part of innate immune response, and display diverse and complex antimicrobial activities against a broad range of Gram negative and Gram positive bacteria, including those resistant to established antibiotic drug therapies, mycobacteria, enveloped viruses, parasites and fungi.  They have gained increasing popularity as a possible alternative to antibiotics due to their broad spectrum activity, low toxicity and most importantly their low tendency to induce antimicrobial resistance (AMR).  The covalent immobilization of these AMPs on surfaces has the potential to impart new properties and functions to surfaces for a wide range of applications. However, most current methods for the production of these surfaces involve multiple chemical steps or do not impart a high degree of control over the chemical functionalities at the surface.  We have developed a facile two-step covalent grafting of the AMP nisin to polystyrene surfaces.   Functionalisation is achieved using an atmospheric pressure plasma jet and the reaction is monitored and compared with a standard wet chemical functionalisation approach.