Dual-fluorophore ratiometric pH nanosensor with tuneable pK(a) and extended dynamic range

Ratiometric pH nanosensors with tuneable pK(a) were prepared by entrapping combinations of two pH-sensitive fluorophores (fluorescein isothiocyanate dextran (FITC-D) and Oregon Green (R) dextran (OG-D)) and a reference fluorophore (5-(and-6)-carboxyte-tramethylrhodamine dextran (TAMRA-D)), in a biocompatible polymer matrix. Dual-fluorophore pH nanosensors permit the measurement of an extended dynamic range, from pH 4.0 to 7.5.