We present a novel strategy for label-free detection of glucose based on CdSe/ZnS core/shell quantum dots (QDs).
We exploit the concentration-dependent, narrowband absorption of the hexokinase-glucose 6-phosphate
dehydrogenase enzymatic assay to selectively filter a 365-nm excitation source, leading to a proportional decrease in
the photoluminescence intensity of the QDs. The visible wavelength emission of the QDs enables quantitative
readout using standard visible detectors (e.g., CCD). Experimental results show highly linear QD
photoluminescence over the clinically relevant glucose concentration range of 1-25mM, in excellent agreement with
detection methods demonstrated by others. The method has a demonstrated limit of detection of 3.5μM, also on par
with the best proposed methods. A significant advantage of our strategy is the complete elimination of QDs as a
consumable. In contrast with other methods of QD-based measurement of glucose, our system does not require the
glucose solution to be mixed with the QDs, thereby decreasing its overall cost and making it an ideal strategy for
point-of-care detection of glucose in low-resource areas. Furthermore, readout can be accomplished with low-cost,
portable detectors such as cellular phones, eliminating the need for expensive and bulky spectrophotometers to
output quantitative information. The general strategy we present is useful for other biosensing applications
involving chemistries with unique absorption peaks falling within the excitation band of available QDs.