Label-based and label-free electrochemical DNA biosensors for the detection of viruses: A review

An ultrasensitive and label-free DNA biosensor was developed to detect deoxyribonuclease I activity based on electrochemical method.

Fabrication of label-free electrochemical impedimetric DNA biosensor for detection of genetically modified soybean by recognizing CaMV 35S promoter

A label-free electrochemical DNA biosensor based on thionine functionalized reduced graphene oxide

Label-free electrochemical DNA biosensor array for simultaneous detection of the HIV-1 and HIV-2 oligonucleotides incorporating different hairpin-DNA probes and redox indicator

The hepatitis A virus (HAV) presents one of the most important foodborne pathogens causing a worldwide health problem each year. [...]

A label-free, PCR-free and signal-on electrochemical DNA biosensor for Leishmania major based on gold nanoleaves

Label-Free Electrochemical DNA Biosensor for the Detection of Mycobacterium Tuberculosis Using Gold Electrode Modified by Self-Assembled Monolayer of Thiol

A label-free electrochemical impedimetric biosensor was constructed based on gold carbon dots (GCDs) modified screen-printed carbon electrode for the detection of genetic modified (GM) soybean. The structure and property of GCDs were investigated. The GCDs can directly bind to single-stranded DNA probes through Au-thiol interaction and boost electric conductivity for the DNA sensor construction. The quantification of target DNA was monitored by the change of electron-transfer resistance (Ret) upon the DNA hybridization on sensor surface. Under the optimal conditions, the Ret response (vs. Ag reference electrode) increased with the logarithm of target DNA concentrations in a wide linear range of 1.0 × 10-7 - 1.0 × 10-13M with a detection limit of 3.1 × 10-14M (S/N = 3). It was also demonstrated that the proposed DNA sensor possessed high specificity for discriminating target DNA from mismatched sequences. Moreover, the developed biosensor was applied to detect SHZD32-1 in actual samples, and the results showed a good consistency with those obtained from the gel electrophoresis method. Compared with the previous reports for DNA detection, the label-free biosensor showed a comparatively simple platform due to elimination of complicated DNA labeling. Therefore, the proposed method showed great potential to be an alternative device for simple, sensitive, specific, and portable DNA sensor.

A label-free electrochemical biosensor for detection of HIV related gene based on interaction between DNA and protein

The emergence of coronavirus disease 2019 (COVID-19) motivates continuous efforts to develop robust and accurate diagnostic tests to detect severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Detection of viral nucleic acids provides the highest sensitivity and selectivity for diagnosing early and asymptomatic infection because the human immune system may not be active at this stage. Therefore, this work aims to develop a label-free electrochemical DNA biosensor for SARS-CoV-2 detection using a printed circuit board-based gold substrate (PCBGE). The developed sensor used the nucleocapsid phosphoprotein (N) gene as a biomarker. The DNA sensor-based PCBGE was fabricated by self-assembling a thiolated single-stranded DNA (ssDNA) probe onto an Au surface, which performed as the working electrode (WE). The Au surface was then treated with 6-mercapto-1-hexanol (MCH) before detecting the target N gene to produce a well-oriented arrangement of the immobilized ssDNA chains. The successful fabrication of the biosensor was characterized using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and atomic force microscopy (AFM). The DNA biosensor performances were evaluated using a synthetic SARS-CoV-2 genome and 20 clinical RNA samples from healthy and infected individuals through EIS. The developed DNA biosensor can detect as low as 1 copy per μL of the N gene within 5 minutes with a LOD of 0.50 μM. Interestingly, the proposed DNA sensor could distinguish the expression of SARS-CoV-2 RNA in a patient diagnosed with COVID-19 without any amplification technique. We believe that the proposed DNA sensor platform is a promising point-of-care (POC) device for COVID-19 viral infection since it offers a rapid detection time with a simple design and workflow detection system, as well as an affordable diagnostic assay.

Immobilization-free and label-free electrochemical DNA biosensing based on target-stimulated release of redox reporter and its catalytic redox recycling

Fast, sensitive, and easy-to-use methods for detecting DNA related to food adulteration, health, religious, and commercial purposes are evolving. In this research, a label-free electrochemical DNA biosensor method was developed for the detection of pork in processed meat samples. Gold electrodeposited screen-printed carbon electrodes (SPCEs) were used and characterized using SEM and cyclic voltammetry. A biotinylated probe DNA sequence of the Cyt b S. scrofa gene mtDNA used as a sensing element containing guanine substituted by inosine bases. The detection of probe-target DNA hybridization on the streptavidin-modified gold SPCE surface was carried out by the peak guanine oxidation of the target using differential pulse voltammetry (DPV). The optimum experimental conditions of data processing using the Box–Behnken design were obtained after 90 min of streptavidin incubation time, at the DNA probe concentration of 1.0 µg/mL, and after 5 min of probe-target DNA hybridization. The detection limit was 0.135 µg/mL, with a linearity range of 0.5–1.5 µg/mL. The resulting current response indicated that this detection method was selective against 5% pork DNA in a mixture of meat samples. This electrochemical biosensor method can be developed into a portable point-of-care detection method for the presence of pork or food adulterations.

Label free flexible electrochemical DNA biosensor for selective detection of Shigella flexneri in real food samples

An electrochemical nucleic acid biosensor typically involves the immobilization of DNA strands onto a surface, which serves as a recognition element for specific DNA or RNA target molecules.1-3 DNA strands can be single-stranded or double-stranded, and their immobilization onto a surface is crucial for sensing applications. This allows the formation of monolayers which is often used to prevent nonspecific adsorption of interfering molecules onto the surface. This layer acts as a barrier, allowing only specific interactions with the DNA target molecules or analytes of interest. Traditionally, redox mediators such as ferrocyanide/ ferricyanide that undergo reversible oxidation-reduction reactions are often used to detect hybridization of DNA targets with immobilized complementary DNA probes. Under these conditions, the heterogeneous charge transfer rate of redox mediators at the electrode surface is often a key factor taken into account to interpret the sensitivity and efficiency of the biosensor.3-5 In this work, with a set of experiments carried out by hydrodynamic voltammetry and impedance spectroscopy at channel microelectrodes, we propose a new approach supported by numerical modeling to highlight the influence of the mass transport of redox mediators on the response of DNA biosensors. Contrary to what is commonly accepted in the literature, we showed that the presence of DNA monolayers acting as blocking monolayers does not affect the charge transfer rate of redox mediators, regardless of the electrode accessibility (surface coverage). We demonstrated that under flow conditions, the current response of the biosensors was controlled by the mass transport rather than the charge transfer rate of redox mediators. This phenomenon was attributed to the nonlinear effects of diffusion-convection of the redox mediators at the remaining active sites, thereby affecting the overall kinetics of the transduction signal. These experiments, coupled with numerical calculations, allowed us to compare the performance of DNA biosensors obtained with different blocking monolayers and to evaluate the average size of the active sites. In this model, they were assumed to be small compared to the electrode size.This study constitutes an important advance in the field of sensors or biosensors, in the broad sense, as it points out the influence of parameters controlling mass transport and therefore the performance of electrochemical DNA biosensors, such as the density of DNA monolayers, the composition of the blocking agents, and size of holes (active sites). REFERENCES 1 Slinker, J. D.; Muren, N. B.; Gorodetsky, A. A.; Barton, J. K. Multiplexed DNA-Modified Electrodes. J Am Chem Soc 2010, 132 (8). 2 Horny, M. C.; Lazerges, M.; Siaugue, J. M.; Pallandre, A.; Rose, D.; Bedioui, F.; Deslouis, C.; Haghiri-Gosnet, A. M.; Gamby, J. Electrochemical DNA Biosensors Based on Long-Range Electron Transfer: Investigating the Efficiency of a Fluidic Channel Microelectrode Compared to an Ultramicroelectrode in a Two-Electrode Setup. Lab Chip 2016, 16 (22). 3 Zambry, N. S.; Awang, M. S.; Beh, K. K.; Hamzah, H. H.; Bustami, Y.; Obande, G. A.; Khalid, M. F.; Ozsoz, M.; Manaf, A. A.; Aziah, I. A Label-Free Electrochemical DNA Biosensor Used a Printed Circuit Board Gold Electrode (PCBGE) to Detect SARS-CoV-2 without Amplification. Lab Chip 2023, 23 (6). 4 Tersch, C.; Lisdat, F. Label-Free Detection of Protein-DNA Interactions Using Electrochemical Impedance Spectroscopy. Electrochim Acta 2011, 56 (22). 5 Cardoso, A. R.; Moreira, F. T. C.; Fernandes, R.; Sales, M. G. F. Novel and Simple Electrochemical Biosensor Monitoring Attomolar Levels of MiRNA-155 in Breast Cancer. Biosens Bioelectron 2016, 80.

A new label-free electrochemical DNA biosensor is presented based on carbon paste electrode (CPE) modified with gold (Au) and platinum (Pt) nanoparticles to prepare the bimetallic nanocomposite electrode. The proposed sensor was made by immobilization of 15-mer single stranded oligonucleotide probe related to p53 gene for detection of DNA plasmid samples. The hybridization detection relied on the alternation in the guanine oxidation signal following hybridization of the probe with complementary genomic DNA. The technique of differential pulse voltammetry (DPV) was used for monitoring guanine oxidation. To optimize the performance of the modified CPE, different electrodes were prepared in various percentages of Au and Pt nanoparticles. The modified electrode containing 15% Au/Pt bimetallic nanoparticles (15% Au/Pt-MCPE) was selected as the best working electrode. The selectivity of the sensor was investigated using plasmid samples containing non-complementary oligonucleotides. The detection limit of the biosensor was studied and calculated to be 53.10 pg μ L −1. A label-free electrochemical DNA biosensor is presented based on gold and platinum nanoparticles-modified carbon paste electrode. The proposed sensor is made by immobilization of 15-mer single stranded oligonucleotide probe related to p53 gene for detection of DNA plasmid samples.