Principal Supervisor: Professor Paula Mendes - School of Chemical Engineering
Co-supervisor: Tim Overton
PhD project title: Investigating the effect of nanoscale vibration cues on bacterial adhesion for biocatalytic applications
University of Registration: University of Birmingham
Mechanosensitivity is common to a wide variety of cells in many different organisms ranging from bacteria to mammals. All organisms respond to vibration, and bacteria are no exception. It is well established that external vibration can affect bacterial phenotypes, including surface adhesion, proliferation and virulence. Reported studies have shown that low-energy surface acoustic waves generated from electrically activated piezo elements1 and vibrational loads generated by magnetoelastic materials2 can modulate bacterial adhesion. However, how bacteria perceive and respond to vibration cues from their environment is still poorly investigated. A fundamental but unexplored aspect concerns how bacterial adhesion is affected by nanoscale vibration cues. Previous studies have provided evidence that nanotopographical cues (such as size and spacing of topographic features) have a direct influence on bacterial cell attachment.3,4 However, such nanostructures behave as static interfaces. Thus, the question arises concerning the significance of providing such nanostructured interfaces with vibration to influence bacterial adhesion.
Biocatalysis (using enzymes to perform chemical reactions industrially) has numerous advantages over chemically catalysed reactions, including stereoselectivity and regioselectivity of reaction, and the ability to synthesise certain molecules that are currently impossible using chemocatalysis. Biocatalysis is an important tool in the synthesis of small molecule pharmaceutical drugs as well as platform chemical and agrochemicals. Enzymes can be used in suspension or immobilized to surfaces, although they are often used inside bacteria as this offers protection from harsh reaction conditions, regeneration of the enzyme and recycling of cofactors such as Flavin. Recently, we have developed biofilms as platforms for biocatalysis for the generation of pharmaceutical intermediates. Biofilms are tough and resistant to harsh chemicals, and so offer the ability to increase biocatalysis longevity. Biofilms are generated when bacteria adhere to a surface and form a polysaccharide matrix to ‘stick’ themselves down to the surface.
The main research goal of this project is to understand how bacterial adhesion is affected by nanoscale vibration cues. Our vision is that this understanding will inform the future development of new, better biofilm catalysts. Our principal objective is to discover which nanofeatures and vibrational characteristics influence the adhesion of different types of bacteria, through the use of surface engineering technologies to fabricate well-defined dynamics of vibration on surface materials. Adhesion bioassays using a range of representative bacteria will test intrinsic bacterial adhesion properties of the vibrational-responsive surfaces.
The project will comprise three key objectives:
Objective 1. Design and fabrication of piezoelectric polyvinylidene fluoride (PVDF) thin films on glass with or without raised nanostructures. The nanostructures, which will exhibit local resonance, will be tailored in shape (i.e. homogeneous and heterogeneous pillars) and dimensions.
Objective 2. Analysis of the effects of nanoscale vibrational cues on bacterial adhesion patterns and dynamics.
Objective 3. Analysis of biocatalysis performance of vibrationally-developed biofilms in a range of industrially-relevant reactions.
- Hazan, Z.; Zumeris, J.; Jacob, H.; Raskin, H.; Kratysh, G.; Vishnia, M.; Dror, N.; Barliya, T.; Mandel, M.; Lavie, G. Effective prevention of microbial biofilm formation on medical devices by low-energy surface acoustic waves. Antimicrob. Agents Chemother. 2006, 50, 4144-4152.
- Paces, W. R.; Holmes, H. R.; Vlaisavljevich, E.; Snyder, K. L.; Tan, E. L.; Rajachar, R. M.; Ong, K. G. Application of sub-micrometer vibrations to mitigate bacterial adhesion. J. Funct. Biomater. 2014, 5, 15-26.
- Epstein, A. K.; Hochbaum, A. I.; Kim, P.; Aizenberg, J. Control of bacterial biofilm growth on surfaces by nanostructural mechanics and geometry. Nanotechnology 2011, 22, 8.
- Cloutier, M.; Mantovani, D.; Rosei, F. Antibacterial Coatings: Challenges, Perspectives, and Opportunities. Trends Biotechnol. 2015, 33, 637-652.
BBSRC Strategic Research Priority: Industrial Biotechnology and Bioenergy
Techniques that will be undertaken during the project:
Nanostructures will be created using soft lithography replica molding and the nanostructures will be characterised for morphology, composition and wettability using atomic force microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy and contact angle. Biofilms will be analysed using standard microbiology techniques as well as microscopy (confocal laser scanning microscopy, Raman confocal microscopy, atomic force microscopy). Biocatalysis will be measured using HPLC, colorimetry or Raman confocal microscopy, depending upon reaction.
Contact: Professor Paula Mendes, University of Birmingham