An enzyme-free fluorescent sensing platform for the detection of uric acid in human urine

Abstract

An enzyme-free fluorescent sensing platform based on lanthanide metal-organic framework (Eu-BDC, BDC:1,4-benzenedicarboxylic acid) doped electrospinning fiber membrane (Eu-BDC@FM) was established for the detection of uric acid (UA) in human urine. The Eu-BDC@FM has Eu3+ characteristic emission, excellent fluorescence stability in pH 4.5–8.0, appropriate hydrophilicity and good reusability (at least 5 cycles). The fluorescence intensity of Eu-BDC@FM can be quenched by UA through inner filter effect. The relationship between the quenching efficiency and UA concentration [A] accords with Stern-Volmer formula in the range of 0–200 μM: I0/I = 0.0106 [A]+1.0199 (r = 0.9933), where I0 and I are the fluorescence intensity of Eu-BDC@FM immersed in water and the UA aqueous solution respectively. The quenching constant is 10.6 × 103 M−1 and the limit of detection is 0.6 μM. The Eu-BDC@FM-based fluorescent sensing platform was applied to detect UA in real urine samples. The common substances in human urine have no interference with UA sensing, and the recovery is in the range of 95–110% with relative standard deviation less than 2.0%. The proposed method is simple, robust, inexpensive, and has good selectivity, accuracy and precision for quantification of UA in real urine samples.