In situ hybridization of PNA/DNA studied label-free by electrochemical impedance spectroscopy

Abstract

The in situ hybridization kinetics of label-free DNA on mixed monolayers of peptide nucleic acid (PNA) and 6-mercapto-1-hexanol (MCH) on Au electrodes was investigated by electrochemical impedance spectroscopy (EIS) and used to discriminate the fully complementary DNA from the single-base mismatched hybrids.

Label‐Free Impedance Biosensors: Opportunities and Challenges

“…It is also possible that the relationship between target coverage and impedance response ΔZ(θ) is logarithmic, as is the case with most field-effect biosensors [153]. Some authors (e.g., [154,155]) have obtained good fits of experimental data with the Langmuir isotherm, and there has been at least one report of sensor response being exponential in target concentration [156]. One complicating factor is whether the binding is controlled kinetically or reaches equilibrium during the experiment.…”

“…Liu et al reported a DNA sensor based on faradaic impedance spectroscopy and were able to easily detect 1 nM of 15mer target [155].The observed change in R ct is presumably due to electrostatic repulsion between the negatively-charged redox species and negative charge on the DNA. Probes were made of PNA, a DNA mimic with a neutral backbone, to increase fractional R ct change.…”

A Novel Type of Nucleic Acid-based Biosensors: the Use of PNA Probes, Associated with Surface Science and Electrochemical Detection Techniques

“…Moreover, the exact association (hybridisation) and dissociation rate constants can be obtained. Thus, the method is comparable to a fluorescence technique (Liu et al, 2005). Monolayers of cysteine-linked peptide nucleic acid assembled on gold electrodes, were investigated for the sensing of DNA recognition (Degefa et al, 2008).…”

“…Liu et al have studied in situ hybridisation kinetic studies with label-free DNA target oligonucleotides on a mixed monolayer of PNA and mercaptohexanol on Au electrodes using EIS. EIS can be used to follow the in-situ hybridisation kinetics of PNA/DNA by recording the change of R ct with time (Liu et al, 2005). The immobilised PNA probes on the sensor surface are uncharged, and hence, do not affect the charge transfer from the redox indicator Fe(CN) 6 3-/4-to the electrode.…”

“…Under the term "surface" techniques, we will include electrochemical, gravimetric techniques, Quartz Crystal Microbalance (QCM), as well as specifically surface science characterisation techniques like X-ray Photoelectron Spectroscopy (XPS), Reflection Absorption Infrared Spectroscopy (RAIRS), Surface Plasmon Resonance (SPR), Surface Enhanced Raman Scattering (SERS) and Time-of-Flight Ion Mass Spectrometry (ToF SIMS); for the first time, these techniques, rather original when applied to PNA-DNA detection, will be gathered and compared in one chapter. Electrochemical detection of DNA binding to DNA or PNA has been widely described in the literature (Liu et al, 2005;Steichen et al, 2007; Cyclic Voltametry (CV), or more sophisticated, Differential Pulse Voltametry (DPV), Electrochemical Impedance Spectroscopy (EIS), conductivity changes may be used as sensitive transduction techniques. The principles of these electrochemical techniques will be recalled; the advantage of using redox markers or electroactive labels will be considered.…”