Turn-on fluorescent detection of captopril in urine samples based on hydrophilic hydroxypropyl β-cyclodextrin polymer.

Here, one kind of hydrophilic hydroxypropyl β-cyclodextrin cross-linked polymer (HP-CDP) was prepared and used to establish a "turn-on" fluorescent probe for selective determination of captopril in biological samples. The HP-CDP has been synthesized in one step by cross-linking (2-hydroxypropyl)-β-cyclodextrin (HP-β-CD) with a rigid aromatic group linker tetrafluoroterephthalonitrile (TFT), and the synthesis parameters of HP-CDP were optimized with water solubility, yield, and adsorption capacity as indicators. When it was used as a luminescent material, we have found an interesting phenomenon that the fluorescence emission of HP-CDP was quenched after forming a coordination compound with ferric ions, and then recovered after adding a certain concentration of captopril, since captopril can reduce the ferric iron to ferrous ions and cause ligand replacement. Based on this observation, a novel turn-on fluorescent method was developed for the determination of captopril. The method exhibited good linearity in the range of 9.2 × 10-7 to 4.6 × 10-4 M (R2 = 0.9982) and a low detection limit of 1.8 × 10-7 M at optimum HP-CDP concentration, ferric ion concentration, pH, and incubation time. Moreover, interference experiments demonstrated that this fluorescence sensor had excellent selectivity that can commendably resist the interference from potential foreign substances. The proposed method has been successfully applied to determine captopril in human urine samples and may provide outstanding application potential in the future development of sensors. In addition, it is believed that HP-CDP also has a wide range of applications, for example, as a solubilizer, pollutant adsorbent, or drug carrier. Graphical abstract ᅟ.