Escherichia Coli based microfluidic whole-cell glucose biosensor
Diabetes is a long term prevailing disease which affects millions of people worldwide. It is a condition where the body fails to utilize the ingested glucose. There has been a dire need for the development of low cost yet effective glucose sensing device. Present day devices are amperometric and works on generated electrochemical signals.
We propose an idea wherein we exploit the lac operon mechanism of the E.coli to detect the concentration of glucose with respect to the varying color intensity. Microfluidic devices involve reactions between substances which can flow in microlitres (µl). The sensitivity of most reaction mechanisms increases many folds when performed in the microlitre regime. This low cost device could be a probable candidate for sensitive chromometric sensor types. Typical division time for E.coli is 20 minutes. Based on the color intensity, we can determine the concentration of glucose in sample by plotting a graph between concentration and absorbance.
In the absence of glucose, the cell depends on alternative sources such as lactose which require switching on of the lac operon .When introduced to IPTG-X gal solution, the β -galactosidase enzyme produced by the operon breaks down X gal, producing blue color. Hence, higher the glucose concentration, lower is its color intensity. The blue color will be high in a reaction set of low glucose concentration. A PDMS- based device working under this principle can be designed for the detection of varying level of glucose concentration with different blue gradient .This device can be further miniaturized into a compact design allowing detection of liquids in channels of micrometer size.