Poly (3,4-Ethylenedioxythiophene) (PEDOT) is a conductive polymer material invented by Bayer Corporation of Germany, which is made from 3,4-ethylenedioxythiophene (EDOT) and electrochemical sensor with electrode modified by PEDOT film has the characteristics of high sensitivity, portability, fastness, high reproducibility, low cost and real-time on-line detection and analysis. It has been widely researched and applied in many fields. This paper will review the application of PEDOT as an electrochemical biosensor in biomedical field.

Electrochemical biosensor uses solid electrode as the base electrode, immobilizes the biosensitive molecule on the electrode surface, and then the biosensitive molecule can selectively identify the target molecule and capture the target molecule to the electrode surface through the specific recognition between biomolecules. The basic electrode is used as the signal transducer to derive the identification signal of the electrode surface and become the electrical signal which can be measured. It is one of the most ideal detection methods to realize the quantitative or qualitative analysis of the analytic target from the surface. PEDOT has a good biocompatibility, non-toxic, so it can be used to modify the bioelectrochemical sensor electrode to analyze and detect samples in the field of biomedicine.

Dopamine is a key neurotransmitter in the hypothalamus and pituitary gland of mammals. The lack of dopamine can lead to important diseases such as Parkinson's disease and schizophrenia, so the determination of dopamine is of great significance in physiological function and clinical application. Under physiological conditions, dopamine, ascorbic acid and uric acid and other compounds often coexist, their oxidation potential will coincide in the bare electrode, so modified electrode is often used for the selective detection of the above biological substances.

Wang Baoguang et al. [1] obtained PEDOT/Au composite modified electrode for dopamine electrochemical detection using sodium p-toluenesulfonate as the supporting electrolyte in the aqueous solution on the indium tin oxide conductive glass. The results showed that the linear range of dopamine was 5×10-6~1×10-4mol/L by differential pulse voltammetry in the neutral pH solution, and the detection limit was up to 1×10-8mol/L with PEDOT/Au composite electrode, which also can effectively eliminate the interference of ascorbic acid and uric acid, to achieve the simultaneous detection.

Detection of glucose

Glucose sensor has been successfully applied to the determination of glucose in human blood, which not only provides an important basis for medical treatment of diabetes, but also greatly facilitate the daily monitoring blood glucose of diabetic. However, glucose in the general human saliva is 8~12μmol, and can not be detected by the current available glucose sensor.

Kanakamedala et al. [2] demonstrated a glucose sensor with micromolar sensitivity using PEDOT/PSS-based electrochemical transistor with inexpensive and rapid xurography technique. It can detect blood glucose concentration of about 1μmol~10μmol, show good repeatability and sensitivity, and successfully detect glucose content of the human saliva in the expected range.

Detection of alpha-fetoprotein

Serum alpha-fetoprotein (AFP) content is an important indicator for the early diagnosis, efficacy observation and prognosis of primary liver cancer and teratoma. The level of AFP in healthy human serum is lower than 20ng/mL, while the content of AFP in serum of patients with hepatocellular carcinoma is very high, and the detection of alpha-fetoprotein is of great significance in the early stage of diagnosis and treatment of liver cancer.

Liu Keke et al. [3] developed an electrochemical immunosensor based on PEDOT and Azure Ⅰ, which is sensitive to AFP. Under the optimized experimental conditions, the electrode response and AFP concentration are keep a linear relation in the range of 0.01~120μg/L, the detection limit is 0.003μg/L, and its accuracy was no significant difference with ELISA; Cui et al. [4] used electrochemical polymerization method to synthesize a new highly biocompatible polymer composite PEDOT/PEG, and modified with gold nanoparticles. The modified PEDOT/PEG can fix a variety of biological molecules, including antibody AFP, and showed good selectivity, sensitivity, low detection limit as well as good anti-pollution ability.

Because of the porous nanostructures, PEDOT can effectively increase the specific surface area of the electrode and allow some solvent and proactive analyte molecules to enter, thus synthesizing a wide range of complex substances. Unique excellent performance makes PEDOT widely used in the field of sensors, and it is worthy of the researchers to explore and research to further expand its application.

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