Label-free electrochemical detection of short sequences related to the hepatitis B virus using 4,4'-diaminoazobenzene based on multiwalled carbon nanotube-modified GCE.

A novel label-free electrochemical DNA biosensor based on 4,4'-diaminoazobenzene (4,4'-DAAB) and multiwalled carbon nanotube (MWNT)-modified glassy carbon electrode (GCE) for short DNA sequences related to the hepatitis B virus (HBV) hybridization detection was presented. Differential pulse voltammetry (DPV) was used to investigate hybridization event. The decrease in the peak current of 4,4'-DAAB was observed on hybridization of probe with the target. This electrochemical approach was sequence specific as indicated by the control experiments, in which no peak current change was observed when a noncomplementary DNA sequence was used. Numerous factors affecting the target hybridization were optimized to maximize the sensitivity. Under optimal conditions, this sensor showed a good calibration range between 7.94 x 10(-8) M and 1.58 x 10(-6) M, with HBV DNA sequence detection limit of 1.1 x 10(-8) M.

Investigation of the interaction between ssDNA and 2-aminophenoxazine-3-one and development of an electrochemical DNA biosensor.

An electrochemical method was used to probe the interaction between 2-aminophenoxazine-3-one (AP) and the short DNA sequence related to the hepatitis B virus (HBV), and an electrochemical DNA biosensor was developed. The voltammetric signals of AP have been investigated at bare glassy carbon electrode (bare GCE), hybrid double-stranded DNA-modified GCE (dsDNA/GCE), and single-stranded DNA-modified GCE (ssDNA/GCE) by means of differential pulse voltammetry (DPV), and the peak currents increased with respect to the order of electrodes. The extent of hybridization was evaluated on the basis of the difference between signals of AP with a probe before and after hybridization with the complementary sequence. Control experiments with noncomplementary were performed to test the selectivity of the biosensor. With this approach, a sequence of the HBV could be quantified over the range from 3.53 x 10(-7) to 1.08 x 10(-6) M, with a linear correlation of r = 0.9963 and a detection limit of 1.00 x 10(-7) M.

A nucleic acid biosensor for the detection of a short sequence related to the hepatitis B virus using bis(benzimidazole)cadmium(II) dinitrate as an electrochemical indicator.

A novel hybridization indicator, bis(benzimidazole)cadmium(II) dinitrate (Cd(bzim)(2)(NO(3))(2)), was utilized to develop an electrochemical DNA biosensor for the detection of a short DNA sequence related to the hepatitis B virus (HBV). The sensor relies on the immobilization and hybridization of the 21-mer single-stranded oligonucleotide from the HBV long repeat at the glassy carbon electrode (GCE). The hybridization between the probe and its complementary sequence as the target was studied by enhancement of the peak of the Cd(bzim)(2)(2+) indicator using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Numerous factors affecting the probe immobilization, target hybridization, and indicator binding reactions were optimized to maximize the sensitivity and speed of the assay time. With this approach, a sequence of the HBV could be quantified over the range from 1.49x10(-7)M to 1.06x10(-6)M, with a linear correlation of r=0.9973 and a detection limit of 8.4x10(-8)M. The Cd(bzim)(2)(2+) signal observed from the probe sequence before and after hybridization with a four-base mismatch containing sequence was lower than that observed after hybridization with a complementary sequence, showing good selectivity. These results demonstrate that the Cd(bzim)(2)(2+) indicator provides great promise for the rapid and specific measurement of the target DNA.

Nucleic acid biosensor for detection of hepatitis B virus using 2,9-dimethyl-1,10-phenanthroline copper complex as electrochemical indicator.

In this study, an electrochemical DNA biosensor was developed based on the recognition of target DNA by hybridization detection. The study was carried out using glassy carbon electrode (GCE) modified with lable-free 21-mer single-stranded oligonucleotides related to hepatitis B virus sequence via covalent immobilization and [Cu(dmp)(H(2)O)Cl(2)] (dmp=2,9-dimethyl-1,10-phenanthroline) as an electrochemical indicator, whose sizes are comparable to those of the small groove of native double-duplex DNA. The method, which is simple and low cost, allows the accumulation of copper complex within the DNA layer. Electochemical detection was performed by cyclic voltammetry and differential pulse voltammetry over the potential range where the [Cu(dmp)(H(2)O)Cl(2)] was active. Numerous factors affecting the probe immobilization, target hybridization, and indicator binding reactions were optimized to maximize the sensitivity and speed the assay time. With this approach, a sequence of the hepatitis B virus could be quantified over the ranges from 8.82 x 10(-8) to 8.82 x 10(-7) M with a linear correlation of r=0.9937 and a detection limit of 7.0 x 10(-8) M. The [Cu(dmp)(H(2)O)Cl(2)] signal observed from probe sequence before and after hybridization with four bases mismatch containing sequence is lower than that observed after hybridization with complementary sequence.