Abstract
Peptide nucleic acid (PNA), the DNA mimic with electrically neutral pseudopeptide backbone, is intensively used in biotechnologies and particularly in single-base mismatch detection in DNA hybridization sensors. We propose a simple method of covalent end-labeling of PNA with osmium tetroxide, 2,2′-bipyridine (Os,bipy). Os,bipy-modified PNA (PNA–Os,bipy) produces voltammetric stripping peaks at carbon and mercury electrodes. Peak potential ( E p) of one of the anodic peaks of PNA–Os,bipy at the pyrolytic graphite electrode (PGE) differs from E p of the reagent, allowing PNA–Os,bipy analysis directly in the reaction mixture. At the hanging mercury drop electrode (HMDE) the PNA–Os,bipy yields a catalytic peak Cat p , in addition to the redox couples. Using Cat p it is possible to detect purified PNA–Os,bipy down to 1 pM concentration at accumulation time 60 s. To our knowledge this is the highest sensitivity of the electrochemical detection of PNA.
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