Electrochemical Biosensor for Detection of BCR/ABL Fusion Gene Using Locked Nucleic Acids on 4-Aminobenzenesulfonic Acid-Modified Glassy Carbon Electrode

In this study, an electrochemical DNA biosensor was developed for detection of the breakpoint cluster region gene and the cellular abl (BCR/ABL) fusion gene in chronic myelogenous leukemia by using 18-mer locked, nucleic acid-modified, single-stranded DNA as the capture probe. The capture probe was covalently attached on the sulfonic-terminated aminobenzenesulfonic acid monolayer-modified glassy carbon electrode through the free amines of DNA bases based on the acyl chloride cross-linking reaction. The covalently immobilized capture probe could selectively hybridize with its target DNA to form double-stranded DNA (dsDNA) on the LNA/4-ABSA/GCE surface. Differential pulse voltammetry was used to monitor the hybridization reaction on the capture probe electrode. The decrease of the peak current of methylene blue, an electroactive indicator, was observed upon hybridization of the probe with the target DNA. The results indicated that, in pH 7.0 Tris-HCl buffer solution, the peak current was linear with the concentration of complementary strand in the range of 1.0 x 10(-12) - 1.1 x 10(-11) M with a detection limit of 9.4 x 10(-13) M. This new method demonstrates its excellent specificity for single-base mismatch and complementary dsDNA after hybridization, and this probe has been used for assay of PCR real sample with satisfactory results.