Capacitive monitoring of morpholino-DNA surface hybridization

Experimental and theoretical analysis

Napoleon Tercero, Kang Wang, Rastislav Levicky

Research output: Contribution to journalArticle

Abstract

Impedance and cyclic voltammetry methods, complemented by Poisson-Boltzmann (PB) modeling, are used to study hybridization of DNA analyte strands to monolayers of morpholino oligomers (MOs) immobilized by one end to mercaptopropanol-passivated gold electrodes. MOs, like peptide nucleic acids (PNAs), are uncharged molecules that recognize nucleic acids following conventional base-pairing rules. The capacitive response to hybridization, determined from real-time impedance measurements, is analyzed with emphasis on understanding the underlying structural changes and on providing a foundation for label-free diagnostics. The capacitive response is correlated with the instantaneous surface molecular populations by labeling DNA and MO strands with ferrocene tags and using cyclic voltammetry to monitor their respective coverages in real-time. This approach allows analysis of hybridization-induced changes in interfacial capacitance as a function of duplex coverage, the DC bias used for readout, buffer molarity, and probe coverage. The results indicate that unhybridizedMO layers exist in a compact state on the solid support. For hybridized layers, the intrinsic signal per hybridization event is strongly enhanced at low ionic strengths but, interestingly, does not depend on the readout bias in the sampled range negative of the capacitive minimum. A PB model incorporating an effective medium description of the hybridizing films is used to establish how hybridization-derived changes in dielectric composition and charge distribution at the surface translate into experimentally observed variations in interfacial capacitance.

Original languageEnglish (US)
Pages (from-to)14351-14358
Number of pages8
JournalLangmuir
Volume26
Issue number17
DOIs
StatePublished - Sep 7 2010

Fingerprint

Morpholinos
oligomers
Oligomers
DNA
deoxyribonucleic acid
nucleic acids
strands
Cyclic voltammetry
readout
Monitoring
Capacitance
capacitance
Peptide Nucleic Acids
Charge distribution
Nucleic acids
impedance measurement
Ionic strength
Gold
charge distribution
Labeling

ASJC Scopus subject areas

  • Electrochemistry
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Materials Science(all)
  • Spectroscopy

Cite this

Capacitive monitoring of morpholino-DNA surface hybridization : Experimental and theoretical analysis. / Tercero, Napoleon; Wang, Kang; Levicky, Rastislav.

In: Langmuir, Vol. 26, No. 17, 07.09.2010, p. 14351-14358.

Research output: Contribution to journalArticle

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