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 th e hepatitis B virus (HBV), using MB as the hybridization indicator was perf ormed. The voltammetric signals of MB have been investigated at bare CPE, d ouble stranded DNA (dsDNA)-modified CPE and single stranded DNA (ssDNA)-mod ified 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 voltam metric signal of MB. The response of the hybridization of the probe with th e single-base mismatch oligonucleotide at CPE was detected by MB. In this c ase, the unbound guanine bases increased the voltammetric signal obtained w ith the hybrid-modified CPE. Control experiments with the noncomplementary oligonucleotides were performed to assess whether the DNA. biosensor respon ds selectively, via hybridization, to the target. Numerous factors, affecting the probe immobilization, target hybridization and indicator binding reactions are optimized to maximize the sensitivity a nd reduce the assay time. The new indicator MB holds great promise for rapi d screening of HBV infection. (C) 2000 Elsevier Science B.V. All rights res erved.