DNA hybridization detection at heated electrodes.
The detection of DNA hybridization is of central importance to the diagnosis and treatment of genetic diseases. Due to cost limitations, small and easy-to-handle testing devices are required. Electrochemical detection is a promising alternative to evaluation of chip data with optical readout. Independent of the actual readout principle, the hybridization process still takes a lot of time, hampering daily use of these techniques, especially in hospitals or doctor's surgery. Here we describe how direct local electrical heating of a DNA-probe-modified gold electrode affects the surface hybridization process dramatically. We obtained a 140-fold increase of alternating current voltammetric signals for 20-base ferrocene-labeled target strands when elevating the electrode temperature during hybridization from 3 to 48 degrees C while leaving the bulk electrolyte at 3 degrees C. At optimum conditions, a target concentration of 500 pmol/L could be detected. Electrothermal regeneration of the immobilized DNA-probe strands allowed repetitive use of the same probe-modified electrode. The surface coverage of DNA probes, monitored by chronocoulometry of hexaammineruthenium(III), was almost constant upon heating to 70 degrees C. However, the hybridization ability of the probe self-assembled monolayer declined irreversibly when using a 70 degrees C hybridization temperature. Coupling of heated electrodes and highly sensitive electrochemical DNA hybridization detection methods should enhance detection limits of the latter significantly.
Flechsig
Gerd-Uwe
GU
Institut für Chemie, Universität Rostock, D-18051 Rostock, Germany. gerd-uwe.flechsig@uni-rostock.de
Peter
Jörg
J
Hartwich
Gerhard
G
Wang
Joseph
J
Gründler
Peter
P
D004247:DNA / Q000032:analysis*; D004563:Electrochemistry; D004566:Electrodes; D006046:Gold / Q000737:chemistry; D009693:Nucleic Acid Hybridization / Q000379:methods*; D012680:Sensitivity and Specificity; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors
D006046:Gold; D004247:DNA