Impedance labelless detection-based polypyrrole DNA biosensor

Abstract

Microelectrodes were fabricated to study impedance labelless detection of DNA hybridization. The probe molecule was attached onto the platinum microelectrode surface by electrochemically copolymerizing pyrrole and the probe oligonucleotides. Measured impedance complexes showed that an electrochemical redox-reaction occurred and the electron-transfer resistance increased after DNA hybridization. It was proposed that the hybridization of DNA in the conductive polymer matrix slowed down the anionic doping/undoping process, resulting impedance changes for the target DNA detection. Impedance measurements were conducted at the complementarily hybridized probe oilgomer-attached polypyrrole film electrodes in different anionic solutions to exam the anionic effects. Results showed that higher concentration and smaller size of anions had the lower electron-transfer resistance. The results not only provide further evidence to support the detection mechanism proposed, but also offer a method to improve the signal to noise ratio for the DNA biosensor. The research also tested the specificity of the methods and experimental results, indicating good specificity of the method. A concept array chip was fabricated and used to demonstrate the capability of the labelless detection method. Nano-Molar concentrations were detected and showed fairly linear responses versus the target molecule concentrations. The method is simple and inexpensive. The technique based genosensors could have potential applications in clinical diagnosis, drug discovery, environmental and food analysis.

Electrochemical immunosensor for detection of antibodies against influenza A virus H5N1 in hen serum

“…The optimal dynamic range with good liner relation was found between the antibody concentration and relative electron transfer resistance ([R i -R 0 ]/R 0 ). This parameter has been proved and reported by Li et al (Li et al, 2005a;Li et al,2005b).…”

“…In this range we have received the good linear relation between the relative electron transfer resistance ([R i -R 0 ] /R 0 ) (Li et al, 2005a, Li et al 2005b) and vaccinated hen serum dilution rate (Fig. 3).…”

Adenosine 5′-triphosphate incorporated poly(3,4-ethylenedioxythiophene) modified electrode: a bioactive platform with electroactivity, stability and biocompatibility

“…5. Randle equivalent circuit has been used to explain the impedance data obtained from conductive polymers such as PPy [25,26], which is composed of the ohmic resistance of the electrolyte solution, R s, in connection in series with parallel elements of double layer capacitance, C dl , and Faraday impedance, Z f . Z f often comprises serially connected electron-transfer resistance, R et , and Warburg impedance, Z w , resulting from the diffusion of ions from the bulk electrolyte to the electrode surface.…”

Carbohydrate-based electrochemical biosensor for detection of a cancer biomarker in human plasma

“…Biosensor technology has the potential to provide fast and accurate detection of cancer biomarkers (Bohunicky and Mousa, 2010;Chikkaveeraiah et al, 2012;Li et al, 2012;Tothill, 2009;Yang et al, 2014). Among the numerous devices reported, electrochemical biosensors are known to display excellent sensing performances with low detection limits (LD) in the picomolar or femtomolar ranges, notably when associated with electrochemiluminescence (ECL) (Hao et al, 2012;Jie et al, 2010;Lin et al, 2011;Zhang et al, 2012) or electrochemical impedance spectroscopy (EIS) (Li et al, 2005a(Li et al, , 2005bDong et al, 2006;D. Wang et al, 2015) as detection methods.…”