Sensory Lipid Membrane Films with Integrated Inorganic Coordination Complexes

Anion detection and recognition in pure water is a significant current challenge in supramolecular chemistry, to this day remains relatively unevolved as a research field. This is due to the fundamental challenges associated with sensing anions, attributed to their strong association with surrounding water molecules (high solvation energies) that needs to be broken in order to bind to a receptor. These receptors often have low solubility in water and poor selectivity for the target anion, exacerbated by weak anion affinity to the binding site.
Inorganic phosphate is ubiquitous as a chemical building block in biological systems, for example being present in the majority of metabolic reactions. It is also highly environmentally relevant, whereby the rising use of fertilisers in agriculture has led to an overabundance of phosphates in waterways. This results in eutrophication, the effects of which can be seen in harmful algal blooms and hypoxic 'dead zones' of aquatic life. Common techniques of detecting phosphate levels vary from the use of traditional molecular fluorescence probes and optical analysis to NMR titration techniques. However, these lab-based methods are typically expensive, time consuming and laborious. Electrochemical sensors, in contrast, are portable, cheap and can be used in the field for continuous monitoring.
The binding environment of a receptor for anions can be effectively engineered to promote high affinity, or strong binding, between the receptor and targeting anion. Sensory films exhibit measurable binding enhancement factors, where solvation effects are controlled. A practical way of controlling such effects is by using such films which afford the ability to tune the interfacial dielectric microenvironment, such that there is reduced charge screening, and hence stronger interactions between the charged anion and binding site. In this project we will develop artificial hydrophobic lipid bilayers, which are an example of such organic sensory films, whereby anion binding motifs can be readily integrated into these bilayers. These membranes will be immobilised on an electrode surface in order to obtain an electrochemical sensor. Electrochemical capacitance measurements will be taken at the interface between the electrode and the film by applying a fixed voltage and varying frequency using a low magnitude alternating current. These capacitance measurements will effectively probe the ability of the film is able to store charge, i.e. the frequency and strength of binding events of phosphate to the membrane anchored receptors at the electrode surface, and as such, quantify phosphate levels.
This project falls in the EPSRC electrochemical sciences, sensors and instrumentation, synthetic coordination chemistry, synthetic supramolecular chemistry research areas within the physical sciences research theme.

The primary impact of the OxICFM CDT will be the highly-trained world-class scientists that it delivers. This impact will encompass both the short term (during their doctoral studies), the medium term (subsequent employment) and ultimately the longer timescale defined by their future careers and consequent impact on science, engineering and policy in the UK.

The impact of OxICFM students during their doctoral studies will be measured by the culture change in graduate training that the Centre brings about - in working at the interface between inorganic synthesis and manufacturing, and fostering cross-sector industry/academia working practices. By embedding not only from larger companies, but also SMEs, we have developed a training regime that has broader relevance across the sector, and the potential for building bridges by fostering new collaborations spanning enormous diversity in scientific focus and scale. Moreover, at a broader level, OxICFM offers to play a unique role as a major focus (and advocate) for manufacturing engagement with academic inorganic synthetic science in the UK.

From a scientific perspective, OxICFM will be uniquely able to offer a broad training programme incorporating innovative and challenging collaborative projects spanning all aspects of fundamental and applied inorganic synthesis, both molecular and materials based (40+ faculty). These will address key challenges in areas such as energy provision/storage, catalysis, and resource provision/renewal necessary to enhance the capability and durability of UK plc in the medium term. To give some idea of perspective, the output from previous CDTs in Oxford's MPLS Division include two start-up companies and in excess of 30 patents.

It is not only in the industrial and scientific realms that students will have impact during their timeframe of their doctorate. Part of the training programme will be in public engagement: team-based challenges in resource development/training and outreach exercises/implementation will form part of the annual summer school. These in turn will constitute a key part of the impact derived from the CDT by its engagement with the public - both face-to-face and through electronic/web-based media. As the centre matures, our aspiration is that our students - from diverse backgrounds - will act as ambassadors for the programme and promote even higher levels of inclusion from all parts of society.

For our partners, and businesses both large and small in the manufacturing sector, it will be our students who are considered the ultimate output of the OxICFM CDT. Our programme has been shaped by the need of such companies (frequently expressed in preliminary discussions) to recruit doctoral graduates who can apply themselves to a broad spectrum of multi-disciplinary challenges in manufacturing-related synthesis. OxICFM's cohort-based training programme integrates significant industry-led training components and has been designed to deliver a much broader skill set than standard PhD schemes. The current lack of CDT training at the interface of inorganic chemistry and manufacturing (and the relevance of inorganic molecules/materials to numerous industrial sectors) heightens the need for - and the potential impact of - the OxICFM CDT. Our students will represent a tangible and valuable asset to meet the long-term skills demand for scientists to develop new materials and nanotechnology identified in the UK Government's 2013 Foresight report.

In the longer term, the broad and relevant training delivered by OxICFM, and the uniquely wide perspective of the manufacturing sector it will deliver, will allow our graduates to obtain (and thrive in) positions of significant responsibility in industry and in research facilities/institutes. Ultimately we believe that many will go on to be future research leaders, driving innovation and changing research culture, and thereby making a lasting contribution to the UK economy.