Schematic description of properties of a solution-phase QD–GBP sensing complex that targets glucose. On the left is a solution containing QDs comprised of cadmium selenide/zinc sulfide conjugated with multiple moieties of an engineered GBP, which also binds to a dextran–quencher complex. The quencher is in close proximity to the QD center, where it quenches outgoing QD emissions by way of FRET. On the right, when glucose is added to a solution containing QDs bound to dextran–quencher complexes, then glucose displaces dextran and the quencher. Without quenching, the result is a concentration-dependent increase in emissions. D, dextran; Q, quencher; ; GLUC, glucose.