A novel boronic acid-based fluorescent sensor for selectively recognizing Fe(3+) ion in real time

Boronic acid provides faster fluorescence response to Fe(3+) 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(3+) ion in real time. After 10 equiv. of Fe(3+) ion (1 mM) was added, the fluorescence of sensor 4 was immediately quenched by 96%. While other ions, including Ba(2+), Ca(2+), Cr(2+), Cd(2+), Co(2+), Cs(2+), Cu(2+), Fe(2+), K(+), Li(+), Mg(2+), Mn(2+), Na(+), Ni(2+) or Zn(2+), respectively, did not change the fluorescence significantly. Further tests indicated that the high selectively sensing Fe(3+) 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(3+) ion among various ions. Therefore, 4 may serve as a potential sensor for continuous monitoring and detecting Fe(3+) ion in real time.