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. 2012 Feb 1;2(2):127–138. doi: 10.7150/thno.3476

Figure 4.

Figure 4

Development of multiplexed system to detect protease activity with QDs. (A) Multiplexed assay of proteases by using QDs with different colors. SA-QD525, SA-QD605, and SA-QD655 were used (from left to right). Biotinylated peptide substrates for MMP-7, caspase-3, and thrombin were conjugated to the AuNPs, and then the resulting Pep-AuNPs were associated with SA-QD525, SA-QD605, and SA-QD655, respectively. (a) SA-QDs only. (b) SA-QDs + respective Pep-AuNPs. (c) SA-QDs + Pep-AuNPs + MMP-7. (d) SA-QDs + Pep-AuNPs + caspase-3, (e) SA-QDs + Pep-AuNPs + thrombin. (f) QDs + Pep-AuNPs + mixture of the respective protease and its inhibitor. (B) High-resolution TEM images of QD-PepMMP7-AuNP assembly (left) before and (right) after incubation with MMP-7. The released AuNPs in enzyme-treated samples were removed by filtration. (C) Changes in the PL intensities of QDs having different colors (SA-QD525, SA-QD605, and SA-QD655) in the presences of biotinylated PepTHR-AuNPs in solution. The molar ratios of Pep-AuNPs to respective QDs were equally maintained at 50. Adapted with permission from 40.