Nanocatalyst-based assay using DNA-conjugated Au nanoparticles for electrochemical DNA detection

Thangavelu Selvaraju, Jagotamoy Das, Kyungmin Jo, Kiyeon Kwon, Chan Hwa Huh, Tae Kyu Kim, Haesik Yang*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

63 Scopus citations


Compared to enzymes, Au nanocatalysts show better long-term stability and are more easily prepared. Au nanoparticles (AuNP8) are used as catalytic labels to achieve ultrasensitive DNA detection via fast catalytic reactions. In addition, magnetic beads (MBs) are employed to permit low nonspecific binding of DNA-conjugated AuNPs and to minimize the electrocatalytic current of AuNPs as well as to take advantage of easy magnetic separation. In a sandwich-type electrochemical sensor, capture-probe-conjugated MBs and an indium-tin oxide electrode modified with a partially ferrocene-modified dendrimer act as the target-binding surface and the signal-generating surface, respectively. A thiolated detection-probe-conjugated AuNP exhibits a high level of unblocked active sites and permits the easy access of p-nitrophenol and NaBh4 to these sites. Electroactive p-aminophenol is generated at these sites and is then electrooxidized to p-quinoneimine at the electrode. The p-aminophenol redox cycling by NaBH4 offers large signal amplification. The nonspecific binding of detection-probe-conjugated AuNPs is lowered by washing DNA-linked MB-AuNP assemblies with a formamide-containing solution, and the electrocatalytic oxidation of NaBH4 by AuNPs is minimized because long-range electron transfer between the electrode and the AuNPs bound to MBs is not feasible. The high signal amplification and low background current enable the detection of 1 fM target DNA.

Original languageEnglish (US)
Pages (from-to)9883-9888
Number of pages6
Issue number17
StatePublished - Sep 2 2008
Externally publishedYes

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Spectroscopy
  • General Materials Science
  • Surfaces and Interfaces
  • Electrochemistry


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