Metal-Ion Amplified Sensor

For practical application, an ideal biosensor must be as straightforward as possible with least number of synthesis and analytical steps. Kraatz and coworkers introduced a simple, label-free and sensitive electrochemical sensor for single nucleotide mismatch detection. This approach relies on the diffusive property of the negatively charged redox probe [Fe(CN)6] and its interplay with matched and mismatched DNA films. 

Based on the initial SECM results, it was postulated that it should be possible to evaluate differences in R t directly by SECM and monitor the amperometric feedback current in the presence and absence of Zn +. The presence of SNP caused an increase in electron transfer rate constant, presumably due to better penetration of 

Recently, the effects of various metal ions on the electrochemical impedance spectra of 25-mer dsDNA films were reported. These metal ions include Mg + and Ca +, known to have high affinity for the phosphate backbone of DNA, the trivalent Al + and La +, and divalent transition metal ions Ni +, Cu +, Zn +, Cd + and Hg +. In all cases, the presence of metal ions decreases the of ds-DNA Films, presumably due to their coordination with the backbone phosphate and potentially association with one or more of the exocyclic 

Af-atoms ofthe purine bases. The ARct ofthe different metal ions was found in the order of Ca = Hg + Cd Ni  

Cu + Zn + which is inversely proportional to their free energies of hydration (see Fig. 7.16) [99]. 

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