New generation cell phones have become an essential component of daily life. In addition to storing and placing calls, they are now used for taking pictures, accessing the internet, and sending/receiving e-mails. Numerous apps are currently available for a tremendous variety of purposes. On February 22, UCLA engineers announced that they had developed a cell phone device that can detect the presence of Escherichia Coli in food and water. They presented the details regarding the new device online in the peer-reviewed journal The Royal Society of Chemistry.
E. Coli is responsible for outbreaks of food poisoning and can cause serious, sometimes life-threatening, infections. E. coli can readily easily contaminate food and drinking water and it poses a significant threat to public health, even in highly developed nations. Each year, it is responsible for a significant number of hospitalizations and deaths. As few as 10–100 E. coli particles can destroy the cells that line the intestines, cause respiratory failure, damage the kidneys, and cause blood clots in the brain, which can result in seizures and paralysis.
The new cell phone–based fluorescent imaging and sensing platform, developed by researchers from the UCLA Henry Samueli School of Engineering and Applied Science, is a lightweight, compact attachment to an existing cell-phone camera. The engineers combined antibody functionalized glass capillaries (small glass tubes to which liquid samples containing bacteria can be added) with quantum dots (semiconductors often used for medical imaging) to detect E. coli particles in liquid samples. The device contains battery-powered, inexpensive light-emitting diodes (LEDs), which can stimulate labeled E. coli particles on the capillary surface. The emissions from the quantum dots can then be imaged with the cell-phone camera via an additional lens inserted between the capillary and the cell phone.
The researchers note that their cost-effective cell-phone attachment functions as a florescent microscope; it can measure the amount of emitted light from each capillary after the bacteria particles are captured from the sample. By measuring the amount of florescent light emission from each tube, the E. coli concentration in the sample can be determined.
The engineers tested the specificity for the detection of E. coli by measuring samples contaminating other bacteria such as Salmonella; this confirmed that the device could specifically target E. coli. In addition, they tested it on food products such as milk. The detection levels of the bacterium were similar to a water sample, which does not contain the protein density of milk. The researchers noted that the device can be adapted to detect other types of bacteria, in addition to E. coli.
This device has a wide variety of practical applications. The small, cost-effective instrument can be readily taken to any location to measure possible contamination of food products, soil, or water.