摘要
We present a novel ratiometric pH sensor design using water-soluble, dual-emission, Mn 2+ -doped quantum dots (Qdots) decorated with D-penicillamine (DPA-MnQdots). In contrast to more commonly used ratiometric pH sensors that rely on the coupling of two fluorophores, our design uses only a single emitter, which simplifies ratiometric sensing and broadens the applications of the sensor. Our single-emitter DPA-MnQdots exhibit two emission bands, at 510 nm (green) and 610 nm (red), which are, respectively, attributable to exciton recombination and emission of the Mn 2+ dopants. The emission intensity ratio (I 510 /I 610 ) of the DPA-MnQdots depends linearly on surrounding pH values within physiological conditions (from pH 4.5 to 8.5). Moreover, the biocompatible DPA-MnQdots were used for long-term monitoring of local pH values in HeLa cells.