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Kinetic and Thermodynamic Hysteresis Imposed by Intercalation of Proflavine in Ferrocene‐Modified Double‐Stranded DNA
Author(s) -
Gebala Magdalena,
La Mantia Fabio,
Schuhmann Wolfgang
Publication year - 2013
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201300045
Subject(s) - proflavine , electron transfer , chemistry , monolayer , intercalation (chemistry) , cyclic voltammetry , redox , ferrocene , electrochemistry , crystallography , electrode , photochemistry , dna , inorganic chemistry , biochemistry
Surface‐confined immobilized redox species often do not show the expected zero peak separation in slow‐scan cyclic voltammograms. This phenomenon is frequently associated to experimental drawbacks and hence neglected. However, a nonzero peak separation, which is common to many electrochemical systems with high structural flexibility, can be rationally assigned to a thermodynamic hysteresis. To study this phenomenon, a surface‐confined redox species was used. Specifically, a DNA strand which is tagged with ferrocene (Fc) moieties at its 5′ end and its complementary capture probe is thiolated at the 3′ end was self‐assembled in a monolayer at a Au electrode with the Fc moieties being located at the bottom plane of the double‐stranded DNA (dsDNA). The DNA‐bound Fc undergoes rapid electron transfer with the electrode surface as evaluated by fast scan cyclic voltammetry. The electron transfer is sensitive to the ion transport along the DNA strands, a phenomenon which is modulated upon specific intercalation of proflavine into surface‐bound dsDNA. The electron transfer rate of the Fc 0/+ redox process is influenced by the cationic permselectivity of the DNA monolayer. In addition to the kinetic hindrance, a thermodynamic effect correlated with changes in the activity coefficients of the Fc 0/+ moieties near the gold‐dsDNA interface is observed and discussed as source of the observed hysteresis causing the non‐zero peak separation in the voltammograms.