Construction of a novel GQD based ratiometric fluorescent composite probe for viscosity detection.

Herein, a novel ratiometric fluorescent composite nanoprobe RV-1@GQDs-OH was developed based on OH-functionalized GQDs (GQDs-OH) and molecular probe (RV-1) via π–π stacking. Compared with the conventional “on–off” viscosity probes, RV-1@GQDs-OH can be successfully applied in living systems for the ratiometric detection of viscosity changes in the viscosity range of 0–600 cP.