Performance of QD-based nanosensor. (a) Fluorescent burst counts versus probe concentration plot for QD-based nanosensors and molecular beacons. The concentration ratio of the Cy5-labelled reporter probe and the biotinylated capture probe was 1 : 1, and the Cy5/QD ratio was maintained at 24 in all experiments. The molecular beacons were Cy5-5́-CGACC CCTGC CACGG TCTGA GA GGTCG-3́-BHQ-2 (stems are underlined). Measurement time was 100 s. (b) Sensing responsivity versus target concentration plot for nanosensors and molecular beacons. Concentrations of receptor, capture probe, and molecular beacon were all 4.8 × 10−10 M and concentration of QD was 2 × 10−11 M, reprinted by permission from Nature Publishing Group: Nature Materials [54], copyright 2005.
