Modified Glucose Meters Measure More Than Sugar

Point-of-care glucose meters have been adapted for other target molecules by coupling them with a class of molecular sensors called functional DNA sensors.

Functional DNA sensors use short segments of DNA that bind to specific targets and a number of functional DNAs and ribonucleic acids (RNAs) are available to recognize a wide variety of targets.

Chemists at the University of Illinois (Urbana-Champaign, IL, USA) modified the meters so that they can be used as simple, portable, inexpensive meters for a number of target molecules in blood, serum, water or food. The DNA segments, immobilized on magnetic particles, are bound to the enzyme invertase, which can catalyze conversion of sucrose to glucose. The user adds a sample of blood, serum, or water to the functional DNA sensor to test for drugs, disease markers, contaminants or other molecules. When the target molecule binds to the DNA, invertase is released into the solution. After removing the magnetic particle by a magnet, the glucose level of the sample rises in proportion to the amount of invertase released, so the user then can employ a glucose meter to quantify the target molecule in the original sample.

The scientists demonstrated using functional DNA with glucose meters to detect cocaine, the disease marker interferon, adenosine, and uranium. The two-step method could be used to detect any kind of molecule that a functional DNA or RNA can bind.

The scientists next plan to further simplify their method, which now requires users to first apply the sample to the functional DNA sensor and then to the glucose meter. Yu Li, PhD, the senior author of the study, said, "We are working on integrating the procedures into one step to make it even simpler. Our technology is new and, given time, it will be developed into an even more user-friendly format.” The study was published on July 24, 2011, in the journal Nature Chemistry.

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