Chemists from the University of Illinois have combined simple, portable and inexpensive glucose meters with molecular sensors to measure a number of target molecules in blood, serum, water or food.
Glucometers are among the few widely available and affordable devices that can provide quantitative measurements. By using enzymes indirectly activated by the presence of a target molecule, sucrose is converted into glucose, and the final glucose reading can be used to quantify the amount of target molecule:
Functional DNA sensors use short segments of DNA that bind to specific targets. A number of functional DNAs and RNAs are available to recognize a wide variety of targets. The DNA segments, immobilized on magnetic particles, are bound to the enzyme invertase, which can catalyze conversion of sucrose (table sugar) 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 researchers have demonstrated the ability of their method to detect cocaine, 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 to. The researchers plan to simplify their method by further integrating the functional DNA sensor and glucose meter. Findings were published in the journal Nature Chemistry.