Low-Dimensional Chemistry

Lead Research Organisation: University of Sheffield
Department Name: Chemistry

Abstract

Miniaturisation has become a familiar aspect of modern technology: every year, laptops get thinner, mobile phones get smaller, and computers get faster as more and more components can be accommodated on their chips. The emergence of nanoscience as a scientific discipline has been driven by the relentless quest by the electronic device industry over the past four decades for ever-faster chips. The importance of miniaturisation is not just in the fact that smaller devices can be packed more closely together, however: when objects become very small indeed, they sometimes acquire entirely new properties that larger objects formed from the same materials do not normally exhibit. Catalysts have been used for over a century to accelerate chemical reactions, and many catalysts consist of metal particles supported on ceramics. For several decades, catalytic converters in car exhausts have used metallic nanoparticles - particles a few billionths of a metre in size - to clean the exhaust gas because the catalytic activity has been found to be dramatically increased by the small size of the active metal. When semiconductors are formed into structures of the same size, they acquire entirely new optical properties purely as a consequence of their small size - for example, they glow brightly when stimulated by electrical current, and the colour of the light emitted is determined by the size of the particle (and can thus be controlled with high precision). These phenomena are referred to as low-dimensional ones: they are new, unexpected phenomena that result only from the small size of the active objects.There is a very important sense in which biological objects may also be said to be low-dimensional. Cells are tiny objects that are driven by processes that involve small numbers of molecules. Biologists have recognised that single molecules are quite different from large groups of molecules, and there has therefore been a lot of interest in studying them, because they may help us to understand much better how larger systems work. However, there are no established tools for building systems of interacting single molecules, what might be called low-dimensional systems . New tools are required to achieve this, and the goal of this programme will be to develop them.We wish to build a synthetic low-dimensional system, which will incorporate biological molecules and synthetic models for them, that replicates the photosynthetic pathway of a bacterium. Photosynthesis is the basis for all life on earth, so it has fundamental importance. However, there are important other motivations for studying the marvellously efficient processes by which biological organisms collect sunlight and use it to live, grow and reproduce. The current concerns about shortage of fossil fuels, and the problems associated with the carbon dioxide produced by burning them, make solar energy a highly attractive solution to many pressing problems. To best exploit the huge amount of solar energy that falls on the earth, even in colder climates like the UK, we may do well to learn from Nature. By building a ship-based system that replicates the photosynthetic behaviour of a biological organism, we will gain new insights into how Natural photosynthesis works. More than that, however, we will develop entirely new, biologically-inspired design principles that may be useful in understanding many other scientific and engineering problems. At a fundamental level, biological systems work quite differently from electronic devices: they are driven by complex signals, they are fuzzy and probabilistic, where microsystems are based on binary logic and are precisely determined. The construction of a functioning low-dimensional system that replicates a cellular pathway will require the adoption, in a man-made structure, of these very different design principles. If we can achieve this it may yield important new insights into how similar principles could be applied to other technologies.

Planned Impact

Much of the emphasis in the programme will be placed upon fundamental research questions. However, it has been designed from the outset with applications in mind. The programme bears on problems of the greatest economic and societal importance. Our choice of exemplar, the fabrication of a planar system for light harvesting, not only has significant potential applications for the fabrication of energy sources for synbio applications but also brings several major technical challenges (fabrication of multicomponent arrays, nano-scale interconnections, integration with nanooptics), each of which has generic relevance to many fields of technology. Training of Personnel We will train 14 individuals (6 PDRAs and 8 PhDs) to work at the cutting edge of molecular nanoscience. We will build an exciting, vibrant programme of research designed to attract the most able young scientists, and will help them to stretch themselves. Their skills and expertise will drive their future careers, and together we will build a programme of outreach activities to take our excitement, and insights from the programme, into the wider community to inspire others. Commercial Impact Although the feed-through into exploitation may take time, many possibilities exist. The applicants have extensive experience of working with industry and spinning out technology. JKH was a founding Director of Infinitesima, which now sells high-speed AFM equipment for in-line process control in silicon fabrication plant. GJL was a member of the board of directors, and then the scientific advisory board of Plasso, a Sheffield spin-out company recently sold to Becton Dickinson. SPA has received extensive funding from Unilever, Procter and Gamble and Reckitt-Benckiser for work on household and personal care products, and SDE has worked with a wide range of nanotechnology-based companies that manufacture polymer and thin-film based products (e.g. Epson, Philips, Sharp). Fundamental knowledge arising from the programme will further stimulate such collaborations with end-users. The development of low-dimensional systems that can reproduce the principal functional elements of photosynthesis would have enormous potential impact, by providing an understanding of how biological design principles may be adapted to better serve anthropogenic requirements. The development of a better understanding of light-harvesting by biological systems, and the ways in which synthetic constructs may be used to replicate and even improve upon the efficiency of biological systems, would be of enormous potential technological value. The project will fit into an over-arching programme of work in the Sheffield Science Faculty designed to harness research across a broad spectrum of disciplines that is focused on the capture and exploitation of solar energy. Project Sunshine aims to harness the power of the sun to tackle the biggest challenge facing the world today: meeting the increasing food and energy needs of the world's population in the context of an uncertain climate and global environment change. It provides a context in which the research is conceived and carried out, and also a platform from which we can interact with key policy makers, and industrial partners. There are many other potential routes to impact. The development of fast, robust routes to immobilised biomolecules interfaced to nanoplasmonic devices, based on robust, scalable polymer surface chemistry that is potentially applicable in industry, is a good example of how we may quickly develop commercialisable technologies in addition to meeting our long-term strategic goals. Our project manager will help identify the most appropriate commercialisation strategy, building on years of experience of knowledge transfer in the Polymer Centre. METRC, of which SPA is a director, provides proof of concept funding for the translation of soft matter research, offering a funded route to realise the potential of our work with UK companies.

Publications

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Alswieleh AM (2014) Zwitterionic poly(amino acid methacrylate) brushes. in Journal of the American Chemical Society

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Blakeston AC (2015) New poly(amino acid methacrylate) brush supports the formation of well-defined lipid membranes. in Langmuir : the ACS journal of surfaces and colloids

 
Description We have developed a toolbox of methodologies that allows us to try to understand how biological systems collect, transmit and store energy. Particular highlights have included: the first molecular resolution images of an intact organelle, the chromatophore vesicle from Rhodobacter sphaeroides; the demonstration of strong coupling between localised surface plasmon resonances and light-harvesting complexes; the demonstration of a light-driven protein device, based around transmembrane proton transport by the protein proteorhodopsin leading to changes in the emission of a dye embedded in a polymer brush layer; the development of a new fouling-resistant, ultra-biocompatible polymer, poly(cysteine metharylate); identification of the location of the cytochrome bc1 complex in the chromatophore vesicle of Rhodobacter sphaeroides, through molecular resolution imaging by AFM and TEM, and the determination of the kinetics of the energy transfer processes; the development of new polymer brush "cushions" that allow reconsitution of biological membranes in two dimensions in such a way that transmembrane protein activity and diffusional transport are retained; the development of an understanding of the nanomechanical properties of polymer brushes; and the development of a suite of new tools for the organisation of functional biologial elements on surfaces.
Exploitation Route A particularly exciting finding has been the discovery of strong coupling between localised surface plasmon resonances and excitons in light harvestign complexes. We have discovered, additionally, the formation of coupled excitonic states in strongly coupled systems that are not found under weak coupling conditions, and evidence for extended excitonic coherence. These findings could provide the foundation for the development of new approaches to the design of molecular photonic materials, which could yield inexpensive photovoltaic devices that achieve high performance efficiencies. These ideas will be developed in future research programmes.
Sectors Electronics,Energy,Environment,Pharmaceuticals and Medical Biotechnology

URL http://www.ldc.group.shef.ac.uk/
 
Description One patent has been filed based on work done by a PhD student funded by the Network. A significant number of outreach events have been organised, including visits to schools, researchers' night activities, visits to churches and social clubs, and a Cafe Scientifique lecture at a venue in Sheffield City Centre.
First Year Of Impact 2014
Sector Chemicals
Impact Types Cultural,Societal

 
Title Lithographic fabrication of macroscopic arrays of gold nanoparticles 
Description A method for preparing densely packed, highly ordered arrays of metal, oxide and polymer nanostructures over macroscopically extended areas cheaply and simply. 
Type Of Material Technology assay or reagent 
Year Produced 2012 
Provided To Others? Yes  
Impact At present stage the methodology has been adopted by several groups of academic collaborators. One group (at Duke University) has built their own apparatus based on ours. 
URL http://www.leggett.group.shef.ac.uk/Easynanofab.html