Novel hybridization indicator methylene blue for the electrochemical detection of short DNA sequences related to the hepatitis B virus

A novel assay for the voltammetric detection of DNA sequences related to the hepatitis B virus (HBV), using MB as the hybridization indicator was performed. The voltammetric signals of MB have been investigated at bare CPE, double stranded DNA (dsDNA)-modified CPE and single stranded DNA (ssDNA)-modified CPE by means of differential pulse voltammetry and cyclic voltammetry and the increased peak currents were observed, in respect to the order of electrodes. The extent of hybridization between the 21-mer oligonucleotides of complementary sequences was determined by the enhancement of the voltammetric signal of MB. The response of the hybridization of the probe with the single-base mismatch oligonucleotide at CPE was detected by MB. In this case, the unbound guanine bases increased the voltammetric signal obtained with the hybrid-modified CPE. Control experiments with the noncomplementary oligonucleotides were performed to assess whether the DNA. biosensor responds selectively, via hybridization, to the target. Numerous factors, affecting the probe immobilization, target hybridization and indicator binding reactions are optimized to maximize the sensitivity and reduce the assay time. The new indicator MB holds great promise for rapid screening of HBV infection. (C) 2000 Elsevier Science B.V. All rights reserved.