Label-Free Electrochemical Hybridization Genosensor for the Detection of Hepatitis B Virus Genotype on the Development of Lamivudine Resistance

Electrochemical probe DNA design in PCR amplicon sequence for the optimum detection of microbiological diseases

Direct electrochemical genosensor was developed for the detection of a probe sequence relative position in a PCR amplicon for the optimum detection of bacterial and microbiological diseases, in this study. The genosensor relies on a label-free electrochemical detection. The amino-linked inosine modified (guanine-free) coequal capture probes which were chosen from different parts of a PCR amplicon, immobilized on to disposable pencil graphite electrodes (PGE) by electrostatically and covalently. As a model case Hepatitis B virus (HBV) genome amplicon was used for the detection and specification. Hybridization was occurred after surface coverage with denatured amplicons. After hybridization, optimum probe sequence position was identified by using the differences between the responses of guanine oxidation signals. The results of this study might have a great convenience for the microbiological diseases detection applications such as DNA micro arrays.

Electrochemical DNA hybridization detection using peptide nucleic acids and [Ru(NH3)6]3+ on gold electrodes

An electrochemical DNA hybridization detection method based on the electrostatic interactions of [Ru(NH3)6]3+ cations with the anionic phosphate backbone of DNA is proposed. PNA molecules are immobilized as capture probes on the gold substrate. The cationic ruthenium complexes do not interact electrostatically with the PNA probes due to the absence of the anionic phosphate groups on the PNA probes. But after hybridization, [Ru(NH3)6]3+ is adsorbed on the DNA backbone, giving a clear hybridization detection signal in ac voltammetry. The analytical parameters (sensitivity, selectivity and reproducibility) are evaluated. Very good discrimination against the single-base mismatch A2143G, internal to the 23S rRNA gene of Helicobacter pylori, is observed. Moreover the system is successfully applied to the detection of complementary PCR amplicons.

Rapid, sequence-specific detection of unpurified PCR amplicons via a reusable, electrochemical sensor

We report an electrochemical method for the sequence-specific detection of unpurified amplification products of the gyrB gene of Salmonella typhimurium. Using an asymmetric PCR and the electrochemical E-DNA detection scheme, single-stranded amplicons were produced from as few as 90 gene copies and, without subsequent purification, rapidly identified. The detection is specific; the sensor does not respond when challenged with control oligonucleotides based on the gyrB genes of either Escherichia coli or various Shigella species. In contrast to existing sequence-specific optical- and capillary electrophoresis-based detection methods, the E-DNA sensor is fully electronic and requires neither cumbersome, expensive optics nor high voltage power supplies. Given these advantages, E-DNA sensors appear well suited for implementation in portable PCR microdevices directed at, for example, the rapid detection of pathogens.