| dc.description.abstract | Point-of-care devices aim to improve medical treatment, by forecasting diseases before symptoms manifest. Multipurpose, portable and easy-to-use sensing devices would increase the accessibility of diagnostics, supporting the early detection and treatment of diseases. Integration into wearable technology would facilitate constant health monitoring, optimising diagnostic times. Biosensors based on organic transistors and those fabricated with functionalised organic semiconducting polymers, show potential in advancing healthcare towards this envisioned future. The scope of this thesis explores strategies to covalently interface biological receptors to semiconducting polymer thin-films, fabricate and characterise field-effect transistor devices utilising these thin-films, and explore their use as organic transistor biosensors. The first research chapter (Chapter 3) identifies a foundational organic field-effect transistor (OFET) fabrication methodology incorporating a high-performance polymer (DPP-DTT). Assembly of large-area homogeneous thin-films, via a floating thin-film transfer method was emphasised. Influence of oxygen and nitrogen plasma treatment on the characteristics of OFETs were investigated. Nitrogen plasma modified thin-films observed exploitable chemical functionalities for receptor attachment. In Chapter 4 thin-films composed of DPP-DTT blended with a cross-linking agent, glutaraldehyde, were incorporated into OFETs. The methodology facilitated the attachment of receptors onto the thin-film surface. Morphology, modified surface chemistry and preliminary OFET biosensing performance were investigated. Chapter 5 details research on fabricating OFETs using an azide modified DPP-DTT polymer. Optimisation of the polymer solution and deposition are highlighted, to develop thin-films in OFETs. Receptor functionalisation, capitalising on strain-promoted azide-alkyne click chemistry, was explored. Morphology, modified surface chemistry and OFET performance were investigated. Additionally, research on the development of an organic electrochemical transistor (OECT), fabricated on a flexible substrate is presented. A novel dithienopyrrole (DTP) derivative, endowed with a carboxyl group, was utilised as the channel material upon electropolymerisation. A receptor functionalisation strategy is discussed. Morphology, modified surface chemistry and OECT performance were investigated. The strategies presented can enable the optimisation of organic transistor biosensors, further bridging a reality where such devices are integrated into medicine. As research in this field progresses, the integration of biosensors into medicine will significantly enhance the efficiency and accuracy of diagnostics, paving the way towards personalised and timely healthcare. | en_US |
