Electrolyte-Gated Transistors Biosensors for Healthcare Applications

Electrolyte-gated transistors (EGTs) based on organic semiconductors and graphene derivates are emerging in the field of biosensing because they are ultrasensitive, label-free, can be fabricated on flexible substrates at low cost and interfaced with biological samples.^1,2 We show some examples to demonstrate the possibility to use this technology to develop biosensors for different healthcare applications, by just selecting the most effective device architecture and material.<br/>All the presented devices share a common transistor architecture, consisting of two interdigitated electrodes, source and drain, covered with an active material, in contact with a gate electrode through an electrolyte. The biosensing event takes place at the gate/electrolyte interface, by functionalization of the gold gate with a biorecognition moiety, and it is amplified by the active material channel thanks to the high-capacitance electrical double-layers formed at the gate/electrolyte and electrolyte/channel interfaces.<br/>We fabricated EGTs biosensors for ultrasensitive detection of biomarkers by using different materials in the channel, namely ambipolar Reduced-Graphene Oxide, organic p-type semiconductor TIPS-Pentacene and poly(3,4-ethylenedioxythiophene)polystyrene sulfonate (PEDOT:PSS) polymer mixture.<br/>Thanks to tailored gate bio-functionalization, we realized a disposable rGO-EGT immunosensor for the detection of anti-Infliximab antibodies, which are produced by patients upon treatment with the immunotherapeutic drug Infliximab and can make the therapy ineffective. Furthermore, we developed an Electrolyte-Gated Organic Field-Effect Transistor (EGOFET) immunosensor for the detection of anti-Nivolumab antibodies, based on the organic semiconductor TIPS-pentacene, showing fM theoretical Limit of Detection (LOD).³ We also successfully employed an organic electrochemical transistor (OECT) genosensor for the detection of oligonucleotides, thanks to a facile functionalization process based on polydopamine.⁴ Finally, we demonstrated the possibility to use EGOFET for the specific detection of transcription factors, by using the consensus DNA sequence as biorecognition element.<br/>We conclude that EGTs biosensors show promising performances for the future application at the Point-of-Care but also for fundamental studies on macromolecules interactions.<br/><br/><br/>References<br/>1) Burtscher, B.; Manco Urbina, P. A.; Diacci, C.; <i>Advanced Healthcare Materials</i>. 2021<i>,10 </i>(20), 2100955.<br/>2) Torricelli, F.; <i>Nat. Rev. Methods Prim.</i> 2021, <i>1</i> (66).<br/>3) Sensi, M.; <i>Chem. Commun.</i> 2021, <i>57</i> (3), 367–370.<br/>4) Sensi, M.; <i>Macromol. Mater. Eng.</i> 2022, <i>307</i> (5), 2100880.