International Journal of Electrochemistry / 2011 / Article / Tab 5 / Review Article
Design and Development of Biosensors for the Detection of Heavy Metal Toxicity Table 5 Examples of DNA-based electrodes.
Electrode Immobilisation technique Toxic effect References GCE/ds-DNA Deposition Pb2+ interacts with ds-DNA preferentially at adenine-containing segments, leading to modifications in the double-helical structure. [58 ] SMFE/ss-DNA Inclusion in a CN membrane Pb2+ and Cd2+ covalent bind during complexation with ss-DNA. Constants of binding (estimated from Scatchard graphs):
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(Pb2+ – ssDNA) = (12 ± 0.3)* 105 M−1 ;
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(Fe3+ – ssDNA) = (1.4 ± 0.3)* 105 M−1 ;
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(Cd2+ – ssDNA) = (0.6 ± 0.2)* 105 M−1 . Limits of detection: 10−10 M Pb2+ , 10−9 M Cd2+ and 10−7 M Fe3 . [61 ] Au/ss-DNA. Self assembled method Cd2+ has the ability to be deposited at underpotential conditions onto gold substrates when it is electrochemically reduced. Constant of binding
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(Cd2+ -ssDNA) = 8.33*105 M−1 . Limit of detection: 10 pM Cd2+ . [59 ] SPE/ds-DNA and SPE/MWCNT-ds-DNA Deposition on SPE Sn2+ and As3+ was studied. [62 ]
GCE = glassy carbon electrode; SMFE = stationary mercury-film electrode; CN = cellulose nitrate; MWCNT= multi-wall carbon nanotubes; SPE = screen printed electrode.
