Mapping the mesoscale structural landscape using "sculpted" chiral plasmonic fields

Lead Research Organisation: University of Glasgow
Department Name: School of Chemistry


Spectroscopy can detect and characterise the properties of individual molecules through probing quantised states. It is a ubiquitous tool which has been instrumental in many new discoveries over the last 100 years. The applications of spectroscopy are numerous and wide ranging: it allows astronomers to detect water in the atmospheres of planets light years away; and enables art historians to determine the pigments used by old masters in their paintings. Given the unmitigated successes of the spectroscopic method, characterisation of the mesoscale is still one area which remains unconquered. The mesoscale is the intermediate length scale (10-1000 nm) between the molecular (quantum) and the macroscopic (classical) worlds. The length scale is important because it occupies the range over which collective properties begin to dominate those of individual molecules. For instance, it marks the transition from chemistry to biology, when individual molecular building blocks self-assemble into complex biological architectures. Since mesoscale molecular assemblies are effectively classical bodies, there is no quantised state which is representative of the overall structure of the object that can be probed spectroscopically. This limitation of the optical spectroscopic paradigm does have practical implications. For instance, while atomic and molecular pollutants in water and the atmosphere can be readily detected (even monitored in real time) with spectroscopy, detecting and characterising a mesoscale molecular assembly such as an unknown virus can take a significant amounts of time and resource; thus extending time to diagnosis and effective treatment.

In this proposal we wish to unlock the shackles of the established optical spectroscopic paradigm by using chiral evanescent electromagnetic fields, rather than light, to rapidly detect and characterise mesoscale molecular structure. When light scatters from chiral plasmonic nanostructures, evanescent EM fields are created in the near field which have a chiral asymmetry (i.e. handedness). In essence the near fields are sculpted by the geometry of the nanostructure, and are imbued with a sense of chirality. The Glasgow Group were the first to demonstrate the existence of these chiral fields, and that they could possess enhanced chiral asymmetry (referred to as superchirality) (Nature Nano 2010). The purpose of this proposal is to show that these superchiral fields can uniquely characterise mesoscale molecular structure, through the use of wild type and synthetic viruses as model systems. To illustrate the potential of the spectroscopy, label free detection of viruses spiked into a biofluid will be demonstrated.

Planned Impact

The impact of the proposed research will be discussed in four main areas: economy, knowledge, people, and society

The "technologization" of our fundamental science will focus on research users, quality assurance for biotechnology companies and diagnostics, from the food industry to medical healthcare. Researchers are pushing towards label free detection as this reduces any external effects on the unnecessary effects on the interaction between a target and an analyte due to the molecular labels in the near vicinity. The label-free detection market has a forecasted value of $1.7 billion by 2018. Our long term aim is to provide clinical assays and hit to lead assays for medical and drug discovery industries that utilize our technology. Medical diagnostics depend largely on ELISA assays, where key vendors such as ABCAM and Thermo Fisher Scientific have market capitalisation of £1,160 M and $55,777 M respectively. Drug discovery as a global industry is easily recognizable as a profitable market. However it would be presumptuous to assume we would enter these highly competitive markets at first instance, replacing a tried and tested methodology with our nascent technology. Therefore our immediate aim would be to provide quality assurance tests to the biotech companies (market value >$300 billion), research tools for biologists and disease detecting assays to the food industry with an aim to achieve profitable returns in 5 years through these applications. We can consider optical biosensing companies such as LambdaGen, BioRad (Market Cap. of $4,118 M), BiaCore and BioNavis as our closest competitors.

The knowledge generated by the proposed work will be communicated through standard routes: papers, conferences, etc. The applicants have a good track record of getting results published in high impact factor journals such as Nature, Nature Nano, Advanced Materials, Chem Comm, Nano Lett, Angewandte, and JACS. The pioneering work of the applicants on superchiral fields in (Nature Nano 5, 783 (2010), 257 cits.) has been cited 20 times in the first 12 months since publication placing it comfortably in the top 1% of all papers in chemistry (according to Thomson Reuters Science Watch). The publication record of the applicants is strong and is expected to continue in this manner with targeting of the top tier journals such with the collaborative work proposed here. The PI (MK) will also communicate results through invitation to speak at international meeting and departmental seminars. In the last 6 years MK has been invited to speak at 13 UK and international Physics and Chemistry departments and has received a further 19 invitations as a keynote or plenary lecturer at international conferences.

The research proposal under consideration here is people centred and career development of the team members a key aim. Career development of the PDRAs will be supported by the University of Glasgow's Researcher Development Framework ensuring PDRAs can access training in a broad range of skills, from research integrity, project management and leadership to collaboration, cross-cultural working, and research impact. PDRAs will be provided with training in public engagement, entrepreneurship, bespoke mentoring, and are encouraged to partake in the Scottish Crucible leadership programme.

It will be attempted to communicate a flavour of the research enterprise and its results to the public. As outlined in the case for support we are seeking funds for a demonstration / exhibit which can be shown at science festivals around the country. The school of chemistry also carries out a range of outreach activities, such as the Slaters Chemistry Day, which this demonstration can be shown. We also plan to exhibit the demonstration at the Glasgow Science Centre, with which the investigators have established links.