3D-printed rolling circle amplification chip for on-site colorimetric detection of inorganic mercury in drinking water

Food Chem. 2019 Dec 1:300:125177. doi: 10.1016/j.foodchem.2019.125177. Epub 2019 Jul 13.

Abstract

A point-of-care testing chip was developed for the colorimetric detection of inorganic mercury ion (Hg2+). The disposable chip fabricated by three-dimensional printing technology contains DNAzymes produced by rolling circle amplification (RCA); a color change caused by the enzymatic reaction between DNAzymes and the peroxidase substrate 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) is measured using a portable spectrophotometer. In the "turn-off"-type RCA reaction, the annealing of the T(12) primer that initiates the RCA reaction is blocked by the interaction of thymine with Hg2+; thus, the amount of amplified DNAzymes causing a color change is decreased depending on Hg2+ concentration. The colorimetric signal is enhanced by amplifying double-repeat DNAzymes from a circular DNA template. The chip detected Hg2+ in tap drinking water samples with high sensitivity (lowest validated value: 3.6 μg/L) and showed better selectivity, precision, and reproducibility than conventional analysis instruments. This low-cost easy-to-use platform can reduce the risk of accidental Hg2+ poisoning.

Keywords: 3D-printing; Colorimetric detection; DNAzyme; Drinking Water; Mercury; Point-of-care (POC) testing.

MeSH terms

  • Colorimetry / instrumentation*
  • Colorimetry / methods
  • DNA, Catalytic / chemistry
  • Drinking Water / analysis*
  • Equipment Design
  • Mercury / analysis*
  • Mercury / chemistry
  • Printing, Three-Dimensional*
  • Reproducibility of Results
  • Sensitivity and Specificity
  • Spectrophotometry / methods
  • Water Pollutants, Chemical / analysis*

Substances

  • DNA, Catalytic
  • Drinking Water
  • Water Pollutants, Chemical
  • Mercury