A coumarin-based red-emitting fluorescent probe for sequential detection of Fe3+ and PPi, and its applications in real water sample and bioimaging in vivo

Iron ions (Fe3+) is one of the most abundant and irreplaceable trace elements among many trace elements. The abnormal levels of Fe3+ in human body can cause a number of adverse effects and diseases. Similarly, pyrophosphate (PPi) is involved in a variety of biological metabolic processes and played an important role in many biochemical reactions. The imbalance of PPi levels in the body can also induce same diseases. Hence, it is of great significance to develop a method to detect Fe3+ and PPi. Herein, a coumarin-based red-emitting fluorescent probe (AFY) was reported for sequential recognition of Fe3+ and PPi. In the presence of Fe3+, the fluorescence of probe AFY was distinctly enhanced and AFY-Fe3+ with 1:1 coordination was generated. The complexation constant of Fe3+ and AFY is 1.46×104 M−1. Upon further addition of PPi, the red fluorescence of the AFY-Fe3+ was quenched. The response mechanism of AFY-Fe3+ to PPi can be attributed to the strong binding ability between Fe3+ and PPi, which released AFY from the complex AFY-Fe3+ and restored the nonfluorescence of AFY. The detection limits of AFY to Fe3+ and PPi are 0.35 and 0.72 μM, respectively. Moreover, the semi-quantitative evaluation of Fe3+ in real water samples was realized by solution colorimetry and AFY-based test strips. Concurrently, utilizing AFY-based test strips, the rapid and on-site detection of Fe3+ in real water samples was realized through the smartphone color recognizer App. It is worth mentioning that probe AFY has been successfully applied in bioimaging of Fe3+ and PPi in vivo.