Scanning Electrochemical Microscopy: A Multiplexing Tool for Electrochemical DNA Biosensing

Abstract

Scanning electrochemical microscopy (SECM) translates the current generated by an electrochemical reaction occurring at a tip electrode scanned across a surface substrate into an image. SECM not only provides a simple electrochemical image of the conductive and/or insulating substrate but also provides kinetic information of the heterogeneous electron transfer reactions when the tip electrode approaches the surface. Applications including biosensing have been demonstrated. In this chapter, we will focus on recent advances in the application of SECM toward the label-free detection of base pair mismatches in DNA.Despite having nanometer dimensions, the base pair mismatches along a DNA strand can be readily detected by SECM in an array format through exploiting the negative charge in the vicinity of selfassembled DNA films. The response can be amplified using metal ions to enhance the discrimination between matched and mismatched DNA films. This simple strategy has been used to probe the position of a single nucleotide mismatch, the type of the mismatch, and hybridization position of complementary strand and even allows the identification of various animal species.