Studies On The Carcinoembryonic Antigen, Guanine And Phenols Sensors Based On Organic Electrochemical Transistors

It is important that to detect the related components with high specificity and sensitivity in disease diagnosis, treatment and detection of environmental pollutants. Sensors based on organic electrochemical transistors(OECTs) have attracted many attention recently because of their mass production, light, high sensitivity, low detection limit, easy fabrication, and low cost. In this paper, we prepared the source electrode and drain electrode of OECTs device by a screen-printing method. Meanwhile, the conducting polymer channel was fabricated by patterning a PEDOT:PSS between source electrode and drain electrode using the spin coating apparatus. Moreover, a glassy carbon electrode was appointed to act as the gate electrode of an OECT and the gate electrode interface of the device was further modified. In this paper we present some sensors based on OECTs for the detection of carcinoembryonic antigen, guanine,and phenolics respectively. In addition, the sensors prepared under the best experiment conditions are more advantageous to real applications because of their high sensitivity and low detection limit. The main works are as follows:(1) 4-carboxyphenyldiazonium were immobilized onto the surface of bare glassy carbon electrode by the reduction of N2+(C6H4)COOH, and then the anti-CEA were immobilized onto the ph-COOH/GC electrodes surface by covalent cross-linking. Then the anti-CEA/ph-COOH/GC electrodes were used as the gate electrodes of the PEDOT:PSS-based OECTs. The immunizationcombination of CEA and anti-CEA can change the potential drop at the interface of electrolyte/gate. Thus the effective gate voltage(Vgeff) increases, the sourcedrain current(IDS) decreases. We prepared an OECT-based carcinoembryonic antigen biosensor by the relationship between normalized current response(NCR) and the concentration of arcinoembryonic antigen. The experimental results are as follows: the detection linear range is 1 ng L-1-20 ng L-1; The correlation coefficient is 0.9974; The experimental results show that BSA, Ig G,and thrombin have no interference of CEA detection.(2) MWCNTs were immobilized onto the surface of bare glassy carbon electrode by drop-coating, and then the Au-NPs were immobilized onto the MWCNTs/GC electrode surface by the electroreduction of chloroauric acid.Meanwhile, the AuNPs/MWCNTs/GC electrodes were used as the gate electrodes of the PEDOT:PSS-based OECTs. For the guanine sensor, the reaction of guanine on the AuNPs/MWCNTs/GC gate electrode can induce a potential drop at the surface of the electrode. Thus the effective gate voltage(Vgeff) increases, the source- drain current(IDS) decreases. Therefore, the variation of source-drain current is related to the concentration of guanine. We prepared an OECT-based guanine sensor utilizing the relationship between normalized current response and the concentration of guanine. The experimental results are as follows: the detection linear range are 0.01 μM-1 μM and 1μM-100 μM; the detection limit is 0.009 μM. Compared with traditionalguanine sensors, the sensor we prepared show many advantages in sensing applications because of their low detection limit, good linear relationship, stable performance in electrolyte, and etc.(3) The AuNPs/MWCNTs/GC electrodes were used as the gate electrodes of the PEDOT:PSS-based OECTs. For the phenols sensor, the reaction of phenols on the AuNPs/MWCNTs/GC gate electrode can induce a potential drop at the surface of the electrode. Therefore, the variation of source-drain current is related to the concentration of phenols. We prepared an OECT-based phenols sensor utilizing the relationship between normalized current response and the concentration of phenols. The experimental results are as follows: the OECT-based phenol and p-cresol sensor, the detection linear range are 0.5μM-10 μM and 10 μM-100 μM; the detection limit are 46 nM and 27 nM respectively; for the OECT-based p-chlorophenol sensor, the detection linear range are 1 μM-10 μM and 10 μM-50 μM; the detection limit is 59 nM; The experimental results show that the sensor we prepared have promising applications because of their low detection limit, easy fabrication, low cost, and etc.