Highly selective detection of 5-aminosalicylic acid based on its aggregation-induced emission using black phosphorus quantum dots

In this study, black phosphorus quantum dots (BPQDs) were proposed for the quantitative detection of 5-aminosalicylic acid (5-ASA) based on the aggregation-induced emission (AIE). BPQDs were prepared using black phosphorus (BP) crystal powder as precursor by ultrasonic stripping of the liquid phase and solvent thermal process. BPQDs exhibited blue fluorescence in ultraviolet light with optimum excitation and emission wavelengths of 343 nm and 438 nm, as well as quantum yield (QY) of 4.82%. The fluorescence of 5-ASA was a little weak with the maximum emission wavelength at 506 nm (QY=1.56%), while its fluorescence was significantly enhanced by BPQDs with the QY at 10.96%. As the concentration of 5-ASA increased, the fluorescent color shifted from blue to green. The optimal emission wavelength changed from 438 nm to 506 nm. It might be attributed to the aggregation-induced emission (AIE) of 5-ASA in the presence of BPQDs. There was favorable linear response between the fluorescence enhancement and the concentration of 5-ASA in the range of 0.1-150 μM, with the limit of detection (LOD) at 30 nM. And then an excellent fluorescence probe for 5-ASA detection was successfully prepared and it was used to determine 5-ASA in real samples with satisfactory results.