Disease Biomarkers Sensor Based On Conducting Polymer Nanocomposite

The main contents of this paper are summarized as follows:(1) Significantly enhanced catalytic activity of a nanocomposite composed of conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) doped with grapheme oxide (GO) was achieved through a simple electrochemical reduction process. The nanocomposite (PEDOT/GO) was electrodeposited on an electrode and followed by electrochemical reduction, and the obtained reduced nanocomposite (PEDOT/RGO) modified electrode exhibited lowered electrochemical impedance and excellent electrocatalytic activity towards the oxidation of dopamine. Based on the excellent catalytic property of PEDOT/RGO, an electrochemical sensor capable of sensitive and selective detection of DA was developed. The fabricated sensor can detect DA in a wide linear range from 0.1 to 175 μM, with a detection limit of 39 nM, and it is free from common interferences such as uric acid and ascorbic acid.(2) An aptasensor for the determination of dopamine in human serum and with ultrahigh sensitivity and selectivity was developed. The sensor is based on a nanocomposite consisting of reduced graphene oxide (rGO) and the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT). The PEDOT/rGO interface was prepared by electrochemical polymerization of EDOT using graphene oxide as the dopant which is later electrochemically reduced to form rGO. Subsequent covalent modification of the high surface area composite with a selective aptamer enables highly sensitive and selective detection by differential pulse voltammetry. The calibration plot established at a working voltage of 160 mV displays a linear response in the 1 pM to 160 nM concentration range and an unprecedented detection limit of 78 fM. The sensor is fairly selective in not responding to common interferents, and is reusable after regeneration with a 7 M solution of urea. It was successfully applied to (spiked) serum samples and gave recoveries ranging from 98.3 to 100.7%.(3) A label-free and low fouling biosensor based on functional polyethylene glycols selective for breast cancer susceptibility gene (BR.CA1) was developed. Sensory interfaces were prepared through the modification of a glassy carbon electrode with highly cross-linked polyethylene glycol (PEG) film containing amine groups, followed by the self-assembly of gold nanoparticles and the immobilization of BRCA1 complementary single-strand 19-mer oligonucleotides. In the presence of a specific BRCA1 sequence capture and hybridization results in interfacial change sensitively monitored using electrochemical impedance spectroscopy. The combined utilization of a PEG polymer film and gold nanoparticle mixed interface enables very high levels of sensitivity and a highly effective assaying in real patient samples. Assay linear range was from 50.0 fM to 1.0 nM, with a limit of detection of 1.72 fM. Furthermore, this label-free DNA sensor has been used for assaying BRCA1 in serum samples, showing its feasible potential for diagnostic applications in clinical analysis of breast cancer gene BRCA1. Foreseeable, this sensor made on this basis undoubtedly provide the most effective and sensitive detection for BRCA1.