Membrane-based electrochemical nanobiosensor for escherichia coli detection and analysis of cells viability
Cheng, Ming Soon
Lau, Suk Hiang
Chow, Vincent T. K.
Date of Issue2011
School of Physical and Mathematical Sciences
A sensitive and selective membrane-based electrochemical nanobiosensor is developed for specific quantitative label-free detection of Escherichia coli (E. coli) cells and analysis of viable but nonculturable (VBNC) E. coli cells which remain mostly undetected using current methods. The sensing mechanism relies on the blocking of nanochannels of a nanoporous alumina-membrane modified electrode, upon the formation of immune complexes at the nanoporous membrane. The resulting obstacle to diffusive mass transfer of a redox probe in the analysis solution to the underlying platinum electrode reduces the Faradaic signal response of the biosensor, measured using cyclic voltammetry. Antibody loading under conditions of varying antibody concentrations and pHs are optimized. The biosensor gives a low detection limit of 22 cfu mL ̄¹ (R² = 0.999) over a wide linear working range of 10 to 10⁶cfu mL ̄¹. It is specific toward E. coli with minimal cross-reactivity to two other pathogenic bacteria (commonly found in waters). Relative standard deviation (RSD) for triplicate measurements of 2.5% indicates reasonably useful level of reproducibility. Differentiation of live, VBNC, and dead cells are carried out after the cell capture and quantitation step, by simple monitoring of the cells’ enzyme activity using the same redox probe in the analysis solution, in the presence of glucose.
Environmental science & technology
© 2011 American Chemical Society. This is the author created version of a work that has been peer reviewed and accepted for publication by Environmental Science & Technology, American Chemical Society. It incorporates referee’s comments but changes resulting from the publishing process, such as copyediting, structural formatting, may not be reflected in this document. The published version is available at:[DOI: http://dx.doi.org/10.1021/es200884a ]