Polyelectrolyte brush-functionalized transistors for biosensing applications

Lead Research Organisation: University of Sheffield
Department Name: Physics and Astronomy


Simple and fast in vitro and in vivo detection of warning signs for the presence of diseases has clear long-term benefits. The purpose of this overseas travel grant is to undertake preliminary work linking transistor technologies with stimuli-responsive polyelectrolyte brushes (a brush is a film comprising polymers attached at one end to the surface upon which the film coats) that would signal the presence of a number of factors (molecules or cells) associated, for example, with risks to health. The key challenge is to couple the recognition of the relevant event or interaction with its detection whilst, for in vivo measurements, avoiding any deleterious effects due to the measurement itself. Electrolyte-gated organic field-effect transistors are excellent candidates for addressing these problems because of their environmental versatility (i.e. response to different external stimuli) and their potential for chemical functionality. A typical challenge would be the detection of a response to pH changes associated with regions of inflammation. To achieve this, a grafted polyelectrolyte layer may be used as part of the gate of a transistor. The polyelectrolyte responds to changes in local pH by undergoing a conformational transition, which changes its thickness, and consequently the capacitance of the dielectric layer. Similarly, the response of transistors to the presence of different types of cells, be they cancerous cells, parasites, or bacteria, and may allow early detection of serious conditions, as well as the possibility of better controlling cellular adhesion. Experiments which trigger conformational changes in polymer brushes are an important means of detecting these cells. The purpose of this overseas travel grant is to collect initial data with which to start a new research theme.

Planned Impact

The benefits of transduction technologies in biosensing will have an important application in the early detection of disease. Different types of field-effect transistors have been able to detect biological cells, but this technology is in its infancy. A successful travel grant will enable the PI to develop this field in the UK. The travel grant will enable research that can move in one of many directions, including applications not described in the main proposal. The current proposal targets the detection of biological cells and markers associated with disease. Part of the impact of this proposal is the leverage it would give in acquiring funds from RCUK, H2020, and/or charities. The benefits of having worked with an internationally leading collaborator such as Professor Fabio Biscarini at the University of Modena will further aid these bids.

A successful overseas travel grant would allow further funding to be sought for a specific application. As an example, one such application, might be in the detection of leishmaniasis, for which the use of ELISA (the usual screening diagnostic for many analytes associated with disease) is less routine. This particular application fits well with the PI's current research portfolio, and would dovetail new work on disease detection with his current research on the binding of the pathogen to functionalised surfaces (e.g. atomic force microscope tips coated with sugars). The creation of inexpensive diagnostic tools is particularly appealing for those working with neglected tropical diseases, but equally, the development of techniques which reduce the cost of healthcare is more generally important. The ideas presented here are a starting point, and the technologies are generic, so there should be many applications for these conditions. However, there are other areas where technology of this nature could have an impact, and through the right choice of local, national, and international collaborators, further development of such diagnostic tools will be possible.


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Description In collaborating with the team at Modena I helped understand the behaviour of electrolyte gated organic field effect transistors (EGOFETs) in solution. The Modena team is developing these for biosensing and their function is complicated by environmental factors. We published a piece of work led by a PhD student there showing that all surfaces that can accumulate charges affect the function of such EGOFETs. My growing understanding of salt in solutions led me to work on a smaller piece of theoretical work concerning polyelectrolyte shape/conformation in aqueous solution, which was formally unrelated to the project but benefitted from working in an environment where electrolyte solutions were discussed. This work was subsequently published.
Exploitation Route This is ongoing work into EGOFETs. Whoever is using EGOFETs will need to know the outcomes. The results are basic to the function of such devices.
Sectors Electronics,Healthcare,Pharmaceuticals and Medical Biotechnology

Description The work that I have started under this grant is ongoing, and one PhD student working in the area of materials for organic bioelectronics has just submitted her thesis. She (Emily Hall) was able to collaborate with my partners in Modena, where this OTG was located. Unfortunately the pandemic rather prematurely ended some of this student's work, but another PhD student (Rachel Lee) is continuing where the Emily left off. The main impact from such a grant was always expected to be further grants and collaborations. Brexit has damaged this somewhat. I have subsequently taken an endowed chair at Newcastle, which has good expertise in areas related to biosensing so I am encouraged that this will continue well. Furthermore, Emily was also working with groups in Cambridge (Professors R. Owens and R. Cameron), and it is anticipated that these will continue. This theme was highlighted in my move to Newcastle, and it is to be anticipated that future collaborations will be strong in this area.
First Year Of Impact 2016
Sector Electronics,Healthcare,Pharmaceuticals and Medical Biotechnology