G-quadruplex DNAzyme-based microcystin-LR (toxin) determination by a novel immunosensor

Biosens Bioelectron. 2011 Jul 15;26(11):4393-8. doi: 10.1016/j.bios.2011.04.047. Epub 2011 May 6.

Abstract

In this paper, we demonstrate the application of versatile G-quadruplex-hemin DNAzymes in an immunoassay for detecting Microcystin-LR (MC-LR). Taking advantage of the high peroxidase activity of G-quadruplex-hemin complexes and the enhancement effect of gold nanoparticles (AuNPs), the method showed simple, high sensitive and selectivity detection of target toxin residues in water samples. The coated antigen, MC-LR-ovalbumin (OVA) coated on a plate, competed for MC-LR antibody with added target analyte to form antibody-antigen immune complexes. Subsequently, the immune complex reacted with G-quadruplex-labeled secondary antibodies for colorimetric detection of MC-LR. This assay specifically determined MC-LR in the linear range of 0.1-10 ng/ml, with a limit of detection (LOD) of 0.05 ng/mL for MC-LR. The results indicated that the novel immunoassay was an alternative to traditional plate-based immunoassay for MC-LR residue screening due to this method met the standard of World Health Organization (WHO) requirements for MC-LR content in drinking water (1 ng/mL).

Publication types

  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Toxins / analysis*
  • Biosensing Techniques / methods*
  • Biosensing Techniques / statistics & numerical data
  • DNA, Catalytic
  • G-Quadruplexes
  • Gold
  • Limit of Detection
  • Marine Toxins
  • Metal Nanoparticles
  • Microcystins / analysis*
  • Ovalbumin
  • Water Pollutants, Chemical / analysis
  • Water Supply / analysis
  • Water Supply / standards

Substances

  • Bacterial Toxins
  • DNA, Catalytic
  • Marine Toxins
  • Microcystins
  • Water Pollutants, Chemical
  • Gold
  • Ovalbumin
  • cyanoginosin LR