title: Nano-silver-modified PQC/DNA biosensor for detecting E. coli in environmental water.
abstract: 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.
authors.affiliation: The Department of Chemistry, The University of Hong Kong, Hong Kong SAR, China.
authors.forename: H
authors.initials: H
authors.lastname: Sun
authors.forename: T S
authors.initials: TS
authors.lastname: Choy
authors.forename: D R
authors.initials: DR
authors.lastname: Zhu
authors.forename: W C
authors.initials: WC
authors.lastname: Yam
authors.forename: Y S
authors.initials: YS
authors.lastname: Fung
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods*; D004269:DNA, Bacterial / Q000302:isolation & purification*; D004784:Environmental Monitoring / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D004926:Escherichia coli / Q000235:genetics / Q000302:isolation & purification*; D055617:Micro-Electrical-Mechanical Systems / Q000295:instrumentation*; D020411:Oligonucleotide Array Sequence Analysis / Q000295:instrumentation*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014871:Water Microbiology; D014873:Water Pollutants / Q000032:analysis*
chemical_list: D004269:DNA, Bacterial; D014873:Water Pollutants