Nano-silver-modified PQC/DNA biosensor for detecting E. coli in environmental water

Biosens Bioelectron. 2009 Jan 1;24(5):1405-10. doi: 10.1016/j.bios.2008.08.008. Epub 2008 Aug 13.


To meet the requirement of World Health Organization for zero tolerance of E. coli cell in 100mL drinking water, a new procedure based on photodeposition of nano-Ag at TiO(2)-coated piezoelectric quartz crystal (PQC) electrode was developed to fabricate a highly sensitive PQC/DNA biosensor. Enhancement of 3.3 times for binding of complementary DNA has been shown and attributed to the following effects arising from the nano-Ag coating. First, a large increase in the active surface area and packing density of neutravidin enhances the maximum neutravidin load to 1.8 times of a normal electrode. Second, the functional activity of neutravidin is enhanced by chemical interaction with nano-Ag to give rise to an increase in the binding ratio between neutravidin and biotinylated DNA probe from 1.00:1.76 to 1.00:3.01. Third, the stronger binding leads to a higher stability of the biotinylated DNA probes bound and increase in hybridization with the complementary DNA. Under the optimized conditions for flow analysis with online PCR product denaturing and hybridization, a detection limit of eight E. coli cells are obtained which require sampling at least 800mL water to detect a single E. coli cell in 100mL water.

Publication types

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

MeSH terms

  • Biosensing Techniques / instrumentation
  • Biosensing Techniques / methods*
  • DNA, Bacterial / isolation & purification*
  • Environmental Monitoring / instrumentation*
  • Equipment Design
  • Equipment Failure Analysis
  • Escherichia coli / genetics
  • Escherichia coli / isolation & purification*
  • Micro-Electrical-Mechanical Systems / instrumentation*
  • Oligonucleotide Array Sequence Analysis / instrumentation*
  • Reproducibility of Results
  • Sensitivity and Specificity
  • Water Microbiology*
  • Water Pollutants / analysis*


  • DNA, Bacterial
  • Water Pollutants