An electrochemical DNA sensor for detection of cytokeratin 19

A novel assay for the voltammetric detection of DNA sequences relating to cytokeratin 19 by using Hoechst 33258 as the hybridization indicator was reported. The biosensor was developed by using thiolated ssDNA as the capture probe for hybridization with CK19 gene on a gold electrode. A significant increase of the peak current for Hoechst 33258 upon hybridization of immobilized ssDNA with target DNA was observed. This peak current change was used to monitor the recognition of the CK19 DNA sequence. Immobilization and hybridization conditions determining the performance of the electrochemical assay were investigated. Under optimal conditions, the constructed electrochemical DNA biosensor has excellent specificity for single-base mismatch and complementary after hybridization. A detection limit of 1.8 × 10−8 M for complementary target DNA can be achieved with a good reproducibility.