Whole-cell based assay for arsenite and antimonite on a compact disc centrifugal microfluidics platform for field sensing applications

Anna M. Rothert
University of Kentucky

Biosensing systems such as reporter-gene-based whole cell assays are becoming popular in biological and environmental screening. A whole cell approach to such analyses can provide valuable information about the bioavailable level of a compound of interest. In this study, a whole cell assay based on the expression of the reporter protein GFPuv was used for the sensitive detection of arsenite and antimonite. GFPuv is under the regulatory control of the ars operon of E.coli, which is only expressed in the presence of arsenite/antimonite. The amount of GFPuv fluorescence can be measured and correlated with the concentration of arsenite/antimonite in a sample. This assay has been successfully adapted to a centrifugal microfluidic platform in the shape of a compact disc. Advantages of such a system are reduced sample size, increased speed of analysis, portability, and high throughput capabilities. The applicability, long time storage, and portability of this system may be further enhanced by incorporating dried cells as reagents. Cell cultures were treated with freeze-drying and liquid-drying methods to determine cell viability and assay performance as well as potential for storage. Complete portability would allow this system to be used as a field sensor for measuring bioavailable levels of arsenite/antimonite in the environment.