Studies On The MiRNA24 Biosensing Based On The Organic Electrochemical Transistors

MicroRNAs(miRNAs) is a kind of small RNAs, which is closely associated with the biological metabolism. In recent years, many works have reported that a lot of mi RNAs are closely related to the growth and metastasis of the tumor, therefore, the detection of miRNAs is of great significance for early diagnosis of disease, especially for cancers. Electrochemical biosensors which have many advantages, such as easy of operation, high sensitivity, fast response time, and etc., were widely used in the miRNAs detection. In this paper, we prepared the organic electrochemistry transistors(OECTs) based on the PEDOT:PSS active layer. Various modified electrodes were prepared and used as the gate electrodes of OECTs. The performances of the prepared OECT devices were investigated. The electrochemical miRNAs biosensors based on the signal amplification of OECTs devices were constructed. The main works are as follows:(1) Screen printing technique was used to prepare carbon source and drain electrodes. The PEDOT:PSS active layer was prepared by spin-coating method and was used to prepare OECT devices. The Au electrodes were modified with HS-DNA capturing probe(complement with miRNA24 target), and were used as the gate electrodes of the OECTs-based miRNA24 biosensor. Under the optimal condition, the detection limit of the biosensor is 20 p M; the linear range is 1 nM- 200 nM; and the sensitivity is 4.903 nM-1; the selectivity is good, the response of the sensor on miRNA29 and mismatch mi RNA24 is very low.(2) HS-DNA capturing probes were fixed on the Au electrode surface through the Au-S bond, and the modified electrodes were used as the gate electrodes of OECTs. The mi RNA24 biosensor was constructed based on the OECTs device using signal amplification of potassium ferrocyanide probe, and the its properties were investigated in detail. Under the optimal condition, the detection limit of the biosensor is 30 fM; the linear range is 10 pM- 10 n M; and the sensitivity is 0.05989 decade-1.(3) The OECT devices using carbon paste electrodes and Au/Ti electrodes were prepared, and the transfer performance, output characteristics, and the stability and etc. of the OECT devices were investigated in detail. Moreover, in order to improve the sensitivity of the sensor, we electrodeposited gold nanoparticles on the gate electrode, and constructed the miRNA24 biosensor based on gold nanoparticles. The feasibility of the biosensor for the miRNA24 detection is preliminarily evaluated.