Two-Dimensional Polymer Films as a Suitable Platform to Covalent Graft Antibody Receptors in an Electrolyte-Gated Organic Field Effect Transistor Bioassay

Although organic field effect transistor (OFET)-based biosensors have aroused great interest due to their advantages of easy integration and fast response speed, surface functionalization of the sensing interface to achieve high sensitivity and outstanding selectivity while maintaining or minimizing the effect on the performance of OFETs is still extremely challenging. Herein, a carboxyl-functionalized two-dimensional polymer film (2DP) is prepared by the Langmuir-Blodgett (LB) method, which forms a heterojunction with a polymer semiconductor and is used to covalently bond the prostate-specific antigen (PSA) antibody receptor. The ordered periodic structure of 2DP films arranges active sites regularly, providing a suitable platform for high surface loading of receptors, and the weak van der Waals interaction between the 2DP and the semiconductor minimizes the effect on the mobility of charge carriers. The results confirm that the construction of the van der Waals heterojunction has a slight effect on the electron transport of the semiconductor channel and maintains the minimum distance between target molecules and the charge transport semiconductor. Electrolyte-gated organic field effect transistor (EGOFET) biosensors modified with 2DP films as receptor layers showed excellent selectivity in the detection of PSA, and the detection accuracy (0.22 pg/mL) was much lower than its clinical detection limit of 4 ng/mL. The results of PSA detection in serum samples of clinical prostate cancer patients show that EGOFET biosensors can accurately screen positive samples, which is consistent with the results of the clinical electrochemiluminescence (ECL) method.