Selective Response of Organic Electrochemical Transistor by a Potentiodynamic Approach

Organic electrochemical transistors (OECTs) are finding growing interest in the field of biological and chemical sensing. Although the OECT transduction is based on electrochemical reactions, the transistor architecture offers several advantages as compared to amperometric sensors such as signal amplification, use of easy and cheap readout electronics, low supply voltage (usually &lt; 1 V), low power operation (&lt; 100 μW), bio-compatibility. Moreover, OECTs can be easily miniaturized and adapted to non-flat, flexible and even textile devices [1]. Since electrochemical transduction usually detects all redox-active compounds in a sample, selectivity remains an open issue that should be addressed to achieve a reliable measure. Our group has developed a potentiodynamic approach for the selective detection of dopamine (DA) in the presence of interfering compounds (ascorbic acid, AA, and uric acid, UA) [2]. The trans-conductance curves allow linear calibration plots for AA, UA and DA and to separate the redox waves associated witheach compound with performances comparable or even better than those obtained by differential pulse voltammetry.<br/>This contribution describes the recent achievements of OECT sensors, based on the potentiodynamic approach, to the design of robust and selective devices able to perform real-time analyses that do not strictly rely on laboratory facilities. The detection of the fat-soluble Vitamin A has been carried out in organic environment [3]. The OECT behaviour was thoroughly characterized, its structure was optimised and both potentiostatic and potentiodynamic detections were investigated. The potentiostatic determination exhibited a gain of 100 with respect to the electrochemical signal represented by Vitamin A oxidation current and the limit of detection was as low as 115 nM, but it did not address selectivity issues. On the other hand, the potentiodynamic approach showed a higher detection limit, but the sensor displayed selectivity in the presence of α-Tocopherol.<br/>Excellent performances were found when analyzing commercial food fortifiers and a multivitamin premix powder, encouraging results to these bioelectronic devices beyond the watery part of life and biology, where they have already proved to provide uniquely performing electrochemical interfaces. Finally, ongoing research deals with potentiodynamic determination of uric acid in saliva with the aim to estimate oxidative stress.<br/><br/><br/>REFERENCES<br/><br/>[1] I. Gualandi, M. Tessarolo, F. Mariani, L. Possanzini, E. Scavetta, B. Fraboni, <i>Polymers</i> <b>2021</b>, <i>13</i>, 894.<br/>[2] I. Gualandi, D. Tonelli, F. Mariani, E. Scavetta, M. Marzocchi, B. Fraboni, <i>Sci. Rep.</i> <b>2016</b>, <i>6</i>, 35419.<br/>[3] L. Salvigni, F. Mariani, I. Gualandi, F. Decataldo, M. Tessarolo, D. Tonelli, B. Fraboni, E. Scavetta, <i>Sens. Actuators B</i> <b>2023</b>, <i>393</i>, 134313.