A Water‐Stable Europium Metal‐Organic Framework as a Turn‐Off Fluorescence Sensor for Ascorbic Acid Detection in Human Serum

Abstract

AbstractAscorbic acid (AA) is a biomarker of some nervous system diseases, whose detection is of significance in many fields. The hydrothermal reaction of naphthalene‐2,6‐dicarboxylic acid (H2NDBC) with Eu3+ produced a europium MOF, Eu‐NDBC. Eu‐NDBC emits the combined emissions from the intraligand charge transfer (ILCT) of NDBC2− ligand and 5D0→7Fj (j=1–4) transfers of Eu(III). The factors of MOF dosage, pH and fluorescence response time are optimized as 0.6 mg, 7.35, and 5 min respectively. The sensitivity test shows a linear fitting equation of I0/I=0.00239 ⋅ CAA+1.03774 (CAA=AA concentration), with its limit of detection calculated as 4.53 μM in a wide linear range of 0–900 μM. The linear fitting of Stern‐Volmer equation gives KSV=2.46×103 M−1 and Kq=4.96×106 M−1 S−1, suggesting Eu‐NDBC sensing AA is a dynamic fluorescence quenching process. Nine control amino acids can't affect Eu‐NDBC sensing AA and the emission intensity stay stable in five fluorescence quenching‐recovery cycles. The returned CAA closed to the set CAA and the recoveries around 100 % support the accurate AA detection by Eu‐NDBC in human serum. Totally, Eu‐NDBC can be regarded as a quantitative turn‐off fluorescence sensor to AA with high sensitivity and selectivity, rapid response and durability.