A novel boronic acid-based fluorescent sensor for selectively recognizing Fe ion in real time.

Boronic acid provides faster fluorescence response to Fe compared to other reported sensors, which is critical for continuous dynamic detection. Herein, we reported a novel boronic acid-based sensor 4 that could recognize Fe ion in real time. After 10 equiv. of Fe ion (1 mM) was added, the fluorescence of sensor 4 was immediately quenched by 96%. While other ions, including Ba, Ca, Cr, Cd, Co, Cs, Cu, Fe, K, Li, Mg, Mn, Na, Ni or Zn, respectively, did not change the fluorescence significantly. Further tests indicated that the high selectively sensing Fe ion benefits from the two boronic acid functionalities in the structure. Moreover, interference experiments showed this sensor has an excellent anti-interference ability. In addition, we performed binding activity test in rabbit plasma and other real samples for practical applications, obtaining similar results. And the thin layer loading sensor 4 was also successfully applied to recognize Fe ion among various ions. Therefore, 4 may serve as a potential sensor for continuous monitoring and detecting Fe ion in real time.