A comparison of cationic and anionic intercalators for the electrochemical transduction of DNA hybridization via long range electron transfer

Electrochemical transduction of DNA hybridization based on the concept of long-range electron transfer using different types of intercalators is reported. This paper examines the performance of two classes of intercalators, based on their charge, that is positively and negatively charged intercalators. The DNA modified electrode was prepared using a two component self-assembled monolayer of thiolated 20-mer probe single-stranded DNA (ss-DNA) and mercaptohexanol (MCH). After hybridization with complementary target ss-DNA the duplex was incubated in an intercalator solution followed by voltammetric measurement in an intercalator free solution. The cations intercalate more rapidly than the anions. However, significant non-specific signals were observed for the cationic intercalators due to non-specific binding to the diluent layer. Anionic intercalator on the other hand showed negligible non-specific signals. (C) 2004 Elsevier B.V. All rights reserved.