A novel and versatile sensing platform based on HRP-mimicking DNAzyme-catalyzed template-guided deposition of polyaniline

A novel, simple, and versatile amperometric sensing platform was developed based on HRP-mimicking DNAzyme-catalyzed template-guided deposition of polyaniline (PANI). Pb2+ was chosen as a model to demonstrate the proof-of-concept of our approach. The Pb2+ aptamer was first self-assembled on the electrode surface. Upon addition of Pb2+, Pb2+ bound to its aptamer to form G-quadruplex (G4). HRP-mimicking DNAzyme with peroxidase catalytic activity was successfully generated after hemin was efficiently intercalated into the G4 structure. Subsequently, HRP-mimicking DNAzyme catalyzed oxidation of aniline to PANI with H2O2 exclusively at the G4 structures, which lead to a readily measurable "turn-on" electrochemical signal. The constructed platform exhibited a good linear response toward Pb2+ over a wide range of concentration from 1.0 x 10(-9) M to 1.0 x 10(-5) M with the detection limit of 5.0 x 10(-19) M. The high performance DNAzyme-based strategy can be further extended to quantify a wide variety of analytes. (C) 2012 Elsevier B.V. All rights reserved.