Potentiometric Detection of DNA Hybridization using Enzyme-Induced Metallization and a Silver Ion Selective Electrode

Abstract

Here we report on a highly sensitive potentiometric detection of DNA hybridization. The new assay uses a low-volume solid-contact silver ion-selective electrode (Ag + -ISE) to monitor the depletion of silver ions induced by the biocatalytic reaction of the alkaline-phosphatase enzyme tag. The resultant potential change of the Ag + -ISE thus serves as the hybridization signal. Factors affecting the potentiometric hybridization response have been optimized to offer a detection limit of 50 fM (0.2 amol) DNA target. The new potentiometric assay was applied successfully to the monitoring of the 16S rRNA of E. coli pathogenic bacteria to achieve a low detection limit of 10 CFU in the 4 μL sample. Such potentiometric transduction of biocatalytically-induced metallization processess holds great promise for monitoring various bioaffinity assays involving common enzyme tags.

Applications of nanomaterials in potentiometric sensors

“…Wang et al [72] reported a highly-sensitive potentiometric biosensor for detecting DNA hybridization based on monitoring the depletion of Ag + ions in the presence of AuNPs induced by the biocatalytic reaction of alkaline phosphate (ALP)-enzyme labels with a solid-contact Ag + -ISlE. The proposed method does not need to dissolve the nanocrystal tracer with H 2 O 2 or to have a preconcentration step.…”

Nucleic acid electrochemical and electromechanical biosensors: a review of techniques and developments

“…The 2-μg/ml limit of detection was established using a synthetic target as in all the work summarized in Table 2, with the exception of (Wu et al 2009) where they used bacterial lysate with no PCR.…”

“…The limits of detection given in Table 2 would be more relevant to food safety and environmental monitoring if they were extracted from experiments that used actual samples of the pathogens as in Wu et al (2009). When authors reported in Table 2 the use of food samples or cell cultures, they use them only to establish selectivity.…”

New Generation Biosensors based on Ellipsometry

“…Potentiometry is the branch of electroanalytical chemistry in which potential is measured under the conditions of no current flow (Eggins, 2002;Ronkainen, 2008). A DNA biosensor was developed by Wu et al (Wu, 2009) and a cell electrochemical biosensor for monitoring hydroquinone cytotoxicity on conductive polymer modified electrode surface by Wang et al were two examples of potentiometric electrochemical biosensors. Impedimetry is an ac method that describes the response of an electrochemical cell to small amplitude sinusoidal voltage signal as a function of frequency (Prodmidis, 2010).…”