Induction of pH Sensitivity on the Fluorescence Lifetime of Quantum Dots by NIR Fluorescent Dyes

Modulation of the fluorescence lifetime (FLT) of CdTeSe/ZnS quantum dots (QDs) by near-IR (NIR) organic chromophores represents a new strategy for generating reproducible pH-sensing nanomaterials. The hybrid construct transfers the pH sensitivity of photolabile NIR cyanine dyes to highly emissive and long-lifetime pH-insensitive QDs, thereby inducing a reproducible FLT change from 29 ns at pH >7 to 12 ns at pH <5. This approach provides an unparalleled large dynamic FLT range for pH sensing at NIR wavelengths.