Rationale Design of Next Generation Antimicrobial Surfaces

A major issue faced by users of biomedical devices is the risk of bacteria-induced infections as biomaterial surface are favourable for bacterial adhesion and biofilm formation. Biofilms on medical devices account for a significant proportion of healthcare-associated infections that are estimated to cost the NHS approximately £1 billion per year. Bacteria that grow in biofilms, a slime-like substance that can grow and cover the surfaces of biomedical devices, can be hundreds of times more resistant to antibiotics and the environment than their planktonic counterpart. Biofilms also act to disperse additional bacterial cells into an infected site once they reach maturity, causing further infection. Both factors make biofilm eradication a great challenge for healthcare. To address the issues caused by bacteria and their biofilms, several different approaches are being taken by researchers to develop 'anti-microbial' and 'anti-fouling' surfaces. The most common strategy uses coatings that release chemical agents such as antibiotics and silver ions to kill the bacteria. Unfortunately, however, these chemical bactericidal strategies can often contribute to the emergence of antimicrobial resistance (AMR). There is, therefore, a pressing need to develop antimicrobial surfaces that do not utilise antibiotics or other antimicrobial agents to kill bacteria.
This project will investigate the alternate approach of developing surface structures that prevent biofouling without the use of chemicals. In the past, cues were taken from nature when designing anti-fouling surfaces and natural surfaces known to exhibit anti-fouling behaviour were mimicked with limited success. These included the surfaces of lotus leaves, cicada wings, and gecko skin, to name but a few. More recently, research has been conducted into developing custom nanostructures such as arrays of nanopillars, nanocones, and nanopits. The sizes of these nanostructures are often chosen arbitrarily or with respect to manufacturing constraints; not as a result of a critical understanding of the underlying physics of the future bacteria-surface interaction. Regrettably, the physics of bacteria-materials surface interactions remains poorly understood, which significantly hinders the innovative design of next generation anti-biofilm surfaces.
Therefore, this project aims to employ a combined experimental and modelling approach to address the fundamental physical questions about how structured antimicrobial surfaces affect bacteria attachment and biofilm formation. This project well aligns with EPSRC remits on healthcare technologies, biomaterials, materials engineering, and soft matter physics.
The specific objectives are:
- Reveal how the surface physical properties of materials control the bacteria-material adhesion under static and flow conditions.
- Develop a robust computational model to predict the effect of surface physical properties of materials and the initial attachment of bacteria on the formation of bacterial biofilms.
- Develop novel material surfaces with prolonged antifouling performance.
To achieve these objectives, the following will be performed:
- Various nanostructured surfaces on typical biomaterials will be designed and manufactured. Each will contain several different nanostructure shapes, sizes and spatial distributions.
- Various clinically relevant bacteria will be cultured on these nanostructures. Both static and flowing tests will be carried out.
- Bacterial attachment and biofilm formation will be analysed using a variety of optical techniques.
- A novel in-house computational model would be developed to study the fundamental physical interactions between bacteria and materials.
- Use experimental results to validate and calibrate the computational modelling.
- Refine the computational models to enable robust predictions of bacterial attachment and biofilm growth.
- Use the validated model to aid in the design of novel antifouling surface