Simple Electrochemical DNA Biosensor Research Articles

New strategy in electrochemical investigation of DNA damage demonstrated on genotoxic derivatives of fluorene

• Electrochemical DNA biosensor based on a glassy carbon electrode was optimized and characterized. • Comprehensive electrochemical biosensing approach was used to detect DNA damage. • DNA damage was detected after interaction with derivatives of fluorene. • Simple electrochemical DNA biosensor was applied for fast and sensitive detection. • Investigation of derivatives of fluorene with dsDNA present in solution was used. In this work, a simple and fast electrochemical DNA biosensor based on a glassy carbon electrode (GCE) was prepared by adsorbing double-stranded DNA (dsDNA) from salmon sperm as a biorecognition layer onto the GCE surface. The dsDNA/GCE biosensor was characterized using modern imaging techniques. The prepared dsDNA/GCE biosensor was used for detection of dsDNA damage by 2-aminofluorene (2-AF), its metabolite 2-acetylaminofluorene (2-AAF), and 2,7-diaminofluorene (2,7-DAF). The electrochemical investigation of the interaction between the selected analytes and dsDNA was conducted using a combination of several electrochemical detection techniques (representing a comprehensive electrochemical biosensing approach allowing an overall assessment of dsDNA damage, even when the intrinsic voltammetric signals of the studied analytes overlap with the dsDNA signals): (i) cyclic voltammetry (CV), square wave voltammetry (SWV), and electrochemical impedance spectroscopy (EIS) at the dsDNA/GCE biosensor, and (ii) differential pulse voltammetry (DPV) for measurements directly in solution at the bare GCE. The changes in dsDNA structure caused by structurally similar analytes were observed. The mutual interaction between derivatives of fluorene and dsDNA caused damaging effects of the test substances on the dsDNA structure in vitro .

Highly sensitive electrochemical DNA sensor based on the use of three-dimensional nitrogen-doped graphene.

This paper describes a voltammetric method for sensitive determination of specific sequences of DNA. The assay is based on three-dimensional nitrogen-doped graphene (3D-NG) which, due to its excellent electrical conductivity, provides a favorable microenvironment to retain the activity of immobilized probe single-stranded DNA and also facilitates electron transfer. The free-standing 3D-NG electrode was characterized by scanning electron microscopy, Raman and X-ray photoelectron spectroscopy, cyclic voltammetry, and electrochemical impedance spectroscopy. Differential pulse voltammetry was applied to monitor DNA hybridization using Methylene Blue as an electrochemical indicator. Under optimal conditions, the peak currents (best measured at 0.28V vs. Ag/AgCl) increase linearly with the logarithm of the concentrations of ssDNA in the 10 f. to 10nM concentrations range, with a 3.5 f. detection limit (at a signal/noise ratio of 3). The biosensor exhibits good selectivity for ssDNA and can distinguish even single-base mismatches. The capability of the method was tested with spiked serum samples, and excellent reproducibility and stability is found. This indicates that the strategy is promising for use in clinical applications. Graphical abstract Three-dimensional nitrogen-doped graphene as an innovative and simple electrochemical DNA biosensor was fabricated and used in a biosensor that shows high sensitivity and good performance in the determination of target DNA in human serum samples.

A sensitive electrochemical DNA biosensor for specific detection of Enterobacteriaceae bacteria by Exonuclease III-assisted signal amplification

A specific and sensitive methodology was developed successfully for quantitative detection of Enterobacteriaceae bacteria by integrating Exonuclease III-assisted target recycling amplification with a simple electrochemical DNA biosensor. After target DNA hybridizes with capture DNA, Exonuclease III can selectively digest the capture DNA, which releases the target to undergo a new hybridization and cleavage cycle on sensor surface, leading to a successful target recycling. Finally, the left capture DNA is recognized by detection probe to produce the detectable signal, which decreases with the increasing target DNA concentration. Under the optimal conditions, the proposed strategy could detect target DNA down to 8.7fM with a linear range from 0.01pM to 1nM, showing high sensitivity. Meanwhile, the sensing strategy was successfully used for detection of Enterobacteriaceae bacteria down to 40CFUmL−1 in milk samples. This strategy presented a simple, rapid and sensitive platform for Enterobacteriaceae bacteria detection and would become a versatile and powerful tool for food safety, biothreat detection and environmental monitoring.