Charge Transduction Through DNA

For example, it was demonstrated by Barton [32] that doublehelical DNA films on gold surface display a marked sensitivity to the presence of base mismatches within the immobilized duplexes. Moreover, it has been observed that mismatch detection is possible regardless of DNA sequence composition and mismatch identity. The presence of mismatches was elucidated based on the electrochemical characteristics of the redox active intercalators bound to the DNA-modified gold surfaces. Coupled redox reactions were employed to induce an electro-catalj ic current and thus increase the method s sensitivity (Fig. 7.4). 

A r-conjugated Fc-modified nucleoside analogue was connected at the 5 end of single-stranded oligonucleotide. After h3ft ridization to the complementary strand, the 3 end of the probe DNA strand was attached to gold electrode by Au-thiol chemistry, Fig. 7.5. 

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FefCN] ] " by methylene blue (MB] at a DNA-modified electrode. LB+ is leucomethylene blue, the product of the electrochemical reduction, (b] Cyclic voltammetry at a gold electrode modified with DNA of 2 mM [Fe(CN]6] (curve 1], 2 p.M MB (curve 2], and 2 mM [FefCNJe] and 2 p.M MB (curve 3]. Reproduced from S. 0. Kelly, E. M. Boon, J. K. Barton, N. M. Jackson, and M. G. Hill, Single-base mismatch detection based on charge transduction through DNA, Nucleic Acids Research, 1999, 27(24], 4830-4837, by permission of Oxford University Press. 

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