Interaction of Nanoparticles with Microbal Populations during Particle Transport

The Royal Society and Royal Academy of Engineers report and the NRCG have identified the need for study into the introduction of anthropogenic nanoparticles into microbial communities and their environmental systems. Therefore it is essential to explore the methods and techniques available that could help to answer some of the research objectives put forward. We propose to evaluate a suite of techniques that could be used in future studies to broaden our knowledge about the impacts nanoparticles may have. The microbial strains tested will have differing cell wall structures (gram-positive versus gram negative) and originate from different environments such as the human gut, the soil and natural waterways. Nanoparticle coatings will be chosen for their hydrophobic and hydrophilic characteristics and the interaction between these coatings and the microbes will be observed using microspectroscopy and fluorophore labels. The influence of nanoparticle coatings on individual microbe cells and their division will be investigated using Raman spectroscopy techniques. Raman tweezers will be used to isolate individual cells to analyse specific changes after coming in contact with the nanoparticles. Labelling nanoparticles with fluorophores will enable their tracking as they are transported as well as their accumulation on cells or mineral surfaces within a porous medium bed. This bed will be composed of clean quartz which is a mineral present in many soil, sediment and groundwater environments. The anticipated results are 1) an evaluation of the techniques for the simultaneous in vitro/in vivo study of nanoparticle transport, uptake and affects on cell growth, 2) an initial assessment of the relative effect of hydrophobic and hydrophilic nanoparticles on selected genetically diverse bacteria and 3) an assessment of the scope for experimental upscaling to the bench-scale packed beds with lengths (30cm) of the same order as a soil column. The experimental design is to combine the investigators' experience on particle transport and biofilm formation in porous granular media, the functionalisation of manufactured nanoparticles to achieve selected surface chemical properties and application of Confocal Raman Microspectroscopy. The overall aim of the project is to provide a platform for work on aspects of nanoparticles surface modification and their interaction with microbes and the natural environment. There is a strong team available to realise these aspirations with strong individual expertise across a number of different disciplines ranging from the use of microspectroscopy, nanoparticle production and the toxicity of pollutants to microbial communities. The wider support infrastructure is also very relevant to the project with help from the Oxford and Appleton laboratory teams as well as the Sheffield cell-mineral programme. This proof-of-concept project has the potential to influence many different areas of research connected to nanoparticles and their effects on natural systems, and will help to provide a solid platform for further research across this area.