A Sequence‐Selective Electrochemical DNA Biosensor Based on HRP‐Labeled Probe for Colorectal Cancer DNA Detection

Abstract

A highly‐sensitive sequence‐selective DNA sensor based on HRP‐labeled probe to detect specific K‐ras gene which is highly associated with colorectal cancer has been reported. Capture probe modified with–SH was first chemically adsorbed on the gold electrode through self‐assembly. Then, the hybridization of a complementary nucleic acid (target DNA:K‐ras gene) and HRP labeled oligonucleotide detection probe occurred in a sandwich way. Finally, H2O2 electroreduction current catalyzed by HRP was measured amperometrically in the presence of hydroquinon as mediator. The sequence selectivity is double guaranteed by the complementary hybridization of target DNA with capture and detection probes. The experimental conditions were optimized. The linear range is 1.17×10−11∼1.17×10−7 mol l−1 with a detection limit of 5.85×10−12 mol l−1. The electrode with capture probe can be reused after regeneration in boiling water.