Rapid whole-cell sensing chip for low-level arsenite detection

A novel whole-cell sensing chip system consisted of a micro-concentrator, a set of electrochemical detection electrodes, and a microfluidic channel was developed for rapid detection of arsenite in water. Firstly, the E. coli cells transformed with arsenited-regulated reporter plasmids were incubated with solution contained arsenite. Under this condition, the level of reporter protein, β-galactosidase, expressed by E. coli cells is dependent on the concentration of arsenite. Using the dielectrophoretic force, the micro-concentrator continuously enriched the E. coli cells into a small area above the embedded detection electrodes. And then the relative expression levels of β-galactosidase were obtained using the electrochemical method to measure the amount of p-aminophenol (PAP) which converted from the p-aminophenyl-β-D-galactopyranoside (PAPG) by β-galactosidase. From the result, it indicates this device can detect as low as 0.1 ppm of arsenite within 30 min. Compared with other traditional detection methods, our new device provides better performance like higher sensitivity, shorter analysis time, and lower cost in detecting the arsenite.