Cell viability measurement using 2′,7′-Bis-(2-carboxyethyl)-5- (and-6)-carboxyfluorescein acetoxymethyl ester and a cantilever sensor

Abstract

Detection of viable pathogenic bacteria has widespread application in food safety and human health. Antibody-based methods require a growth step which limits time-to-results performance. In this study, we use a mass-change sensitive cantilever biosensor and a probe, 2′,7′-bis-(2- carboxyethyl)-5-(and-6)-carboxyfluorescein acetoxymethyl ester (BCECF-AM), that accumulates only in live cells inducing a mass-change response to determine the cell viability in a short time. A poly-l-lysine coated sensor immobilized with live Escherichia coli JM101 (a surrogate for a pathogenic target) at various concentrations was exposed to BCECF-AM in a flow arrangement. A larger resonant frequency decrease in response to 100 μL of 60 μM BCECF-AM was observed when the sensor surface cell concentration was increased from 1 090 ± 580 to 3 960 ± 370 cells/mm2 (n = 5). A log-linear relationship between the sensor surface cell concentration and frequency response was obtained in the range of 1 000-4 000 cells/mm2 and as low as ∼2 000 viable E. coli cells were rapidly detected (<1 h). © 2011 American Chemical Society.