Bench Press

Thankfully food scares like the Salmonella contamination of peanut products from the Peanut Corporation of America are fairly rare in the US the health risk posed by contaminated food and water must be taken extremely seriously and effective means to test and certify food and water safety are of the utmost importance. Despite this even with modern advances some tests can currently take days to verify the safety of food and water samples.

This lag time can ultimately prove disastrous in certain scenarios. For example, the rural
community of Walkerton, Canada experienced E. coli contamination in May, 2000 resulting in seven deaths and hundreds sickened by the contaminated water. Therefore, testing of critical supplies like water ought to be as near real time as possible in order to minimize potential harm.

This brings me to research being conducted by Dr. Shacham-Diamand’s group at Tel Aviv University. Speaking about the dangers of water poisoning Dr. Shacham-Diamand warns “You don’t want hospitals to be sensors for toxicity. That’s too late”. This desire to provide a more rapid and effective testing apparatus propelled Shacham-Diamand’s group to design a “lab on a chip” capable of accurately detecting a wide range of contaminants in water within minutes of simply adding water to the chip.

This “lab on a chip” is built upon genetically engineered E. coli in reaction chambers on a chip as seen in the diagram below (Subfigures A + B). When exposed to nL samples the E. coli luminesce in the presence toxins which are then detected and quantified by the signal strength. Initial experiments done with E. coli containing the lac promoter (activated by IPTG) fused to lux-CDABE genes of V. Fischeri proved the feasibility of utilizing whole cell bacteria in order to generate luminescent signal that could be detected utilizing a solid-state photodetector¹. Other experiments conducted by Dr. Shacham-Diamond’s group have proved the feasibility of detecting a variety of contaminants with genetically engineered E. coli².

Currently, Dr. Shacham-Diamand’s group has worked on further modeling of their chip design (above Subfigure C) in order to optimize the detection of the luminescent signal. The flexibility generated by using genetically engineered E. coli has Dr. Shacham-Diamand’s group looking into alternative applications of their chip such as screening potential cancer drugs.

In the end innovative nanoscale devices like this “lab on a chip” and the DNA-coated nanowire device we blogged about previously show tremendous promise for improving our ability to detect and diagnose a wide range of problems be they contaminated water or diseases.

(Sources: Tel Aviv University , 1 – Towards toxicity detection using a lab-on-chip based on the integration of MOEMS and whole-cell sensors , 2 - Novel Integrated Electrochemical Nano-Biochip for Toxicity Detection in Water)