A facile fluorescence Eu MOF sensor for ascorbic acid and ascorbate oxidase detection

In this work, a facile fluorescence Eu3+-based metal organic frameworks (Eu MOF) sensor for ascorbic acid (AA) and ascorbate oxidase (AAO) detection was developed. The fluorescence of Eu MOF could be effectively quenched by Ce3+ but not Ce4+ at an appropriate concentration, thus, when the reductant AA was added into the solution containing Ce4+, Ce4+ was chemically reduced to Ce3+, which induced the decreased fluorescence signal of Eu MOF. However, when AAO was introduced, AA was effectively oxidized to dehydroascorbic acid (DHAA) under the catalysis of AAO, thus, Ce4+ could not be reduced, resulting in the fluorescence restore of Eu MOF. Hence, the concentration of AA and AAO could be determined by the fluorescence decrease and restore of Eu MOF. The fluorescent platform showed high sensitivity with the limit of detection of 0.32 µM for AA and 1.18 U/L for AAO, respectively. Moreover, the proposed method was successfully applied for AA and AAO determination in real samples, indicating great potential for biomedical application in complex matrices.