Exploiting the Interaction of Metal Ions and Peptide Nucleic Acids−DNA Duplexes for the Detection of a Single Nucleotide Mismatch by Electrochemical Impedance Spectroscopy

摘要

The interaction of the metal ions Mg2+, Zn2+, Ni2+, andnCo2+ with DNA-peptide nucleic acid (PNA) films onna gold surface is studied by electrochemical impedancenspectroscopy in the presence of [Fe(CN)6]3-/4- as thenredox probe. Impedance data were analyzed with thenhelp of a modified Randles’ equivalent circuit. Changesnin the charge-transfer resistance, RCT, decreases in thenorder of Ni2+ > Co2+ > Zn2+ > Mg2+.We interpret thesenresults in terms of stronger interactions for Ni2+ withnthe DNA-PNA film compared to the other metal ions,npotentially involving interactions with the nucleobases,npresumably with the N7 of purines or the N3 ofnpyrimidines. On the basis of these observations, Ni2+nwas chosen to probe the detection of a C-T mismatchnin 15-mer PNA-DNA films. Using Ni2+, it is possiblento detect a single C-T mismatch. The resulting ΔRCT isnlarger for the PNA-DNA hybrid compared to that fornthe identical 15-mer DNA-DNA hybrid.