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DNA hybridization plays an important role in medical diagnostics, drug development and biological threat discovery. Despite the wide use of optical hybridization detection, electrochemical methods, and especially covalently attached redox markers, attain an increasing interest. However, one problem is that the number of suppliers of electrochemically labelled oligonucleotides is very limited. This paper reports about the use of the commercially available fluorescence quenching label dabcyl (p-methyl red) as a redox active DNA-marker. We investigated the polarographic, voltammetric and adsorptive stripping voltammetric behaviour of this compound in a TRIS buffer at pH 7.5 and found that two polarographic waves (at −0.48 and −1.28 V vs. Ag/AgCl) can be easily distinguished compared to only one clear signal between −0.4 and −0.7 V in most voltammetric techniques.The alternating-current voltammetric (ACV) signal of a dabcyl-labelled target at a thiollinker-probe-SAM modified gold disk electrode was very clear but small due to a fast and irreversible decay of the reduction product. Despite of this, non-complementary DNA-strands could be discriminated and at 15 min hybridization time, trace amounts down to 50 nM target concentration could be detected. Such electrochemical use of optically active labels could open new possibilities for spectroelectrochemical studies of DNA hybridization. Keywords: DNA hybridization, Gold electrode, Voltammetry, Dabcyl, Methyl red, Self-assembled monolayer |
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