Studies On The Preparation And Properties Of The MiRNA Biosensors Based On Organic Electrochemical Transistor

In this paper, we prepared the different lengths of the organic electrochemical transistors(OECTs) source-drain electrodes by screen printing technique;and the gate electrode interface of the device was further modified.Construction of glucose and micro RNA(miRNA21) biosensors based on OECTs.Through the transfer characteristics and the output characteristics of device, we evaluated the response performance of the device. Cyclic voltammetry(CV),electrochemical impedance spectroscopy(EIS), amperometric i-t curve(i-t) and other methods were used to characterize the gate electrode interface modification steps, glucose and mi RNA21 detection performances in details.Under the optimal conditions, the organic electrochemical transistors biosensor that we prepared has potential applications in glucose and miRNA detection.The main works are illustrated as follows:(1) The different lengths of organic electrochemical transistors(OECTs) of the source-drain electrodes were prepared. The different lengths of source-drain electrodes and gate electrode materials on transfer characteristics(Ids-Vgs curve)and output characteristics of OECTs devices were studied. The glucose biosensor was constructed by using OECTs as electrochemical signal transducer and amplifier, and modified gold electrodes as gate electrodes. Experimentalresults showed that in the studied range of the source-drain electrode length(0.12-1.2 mm), when source-drain electrode length increased, the initial Ids is decreased; but the OECT devices had good transfer properties. The gate electrode materials will affect the transfer characteristic(Ids-Vgs curve) of OECTs devices. Under the same conditions, the Ids changes with Vgs is more sensitive by using Pt electrode as the gate electrode of OECTs. The performances(detection limit) of glucose biosensors based on OECTs using different length of source-drain electrodes lengths(0.12-1.2 mm) have no obvious difference.(2) The DNA capture probes(complementary with miRNA21) were immobilized onto the bare Au electrode surface by Au-S bond, and the immobilization for probe conditions were optimized. The probe modified electrodes was used as the gate electrode and label-free mi RNA21 biosensor were developed based on the organic electrochemical transistor. The properties of the proposed miRNA21 biosensor were studied in detail. Under the optimal conditions, the results are as follows: the detection linear range is 5 nM-80 nM;the detection sensitivity is 1.768 μM-1; the detection limit is 5 pM; and the sensor has good selectivity and reproducibility.(3) The bare Au electrode surface was modified with gold nanoparticles by electrodeposition method. Through the Au-S bond the DNA capture probe(complementary with miRNA21) were immobilized onto the Au NPs/bare Auelectrode surface, and the probe/Au NPs/Au electrode(MCH/HS-probe/AuNPs/Au) were used as gate electrode of the OECTs. The label-free biosensors based on AuNPs signal amplification effect and the OECTs were constructed to detect miRNA21. The results are as follows: the detection linear range is 1 nM-50 n M; the detection sensitivity is 7.894 μM-1; the detection limit is 2 pM; and the sensor has good selectivity and reproducibility.