Polyelectrolyte brush-functionalized transistors for biosensing applications

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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.