Facile synthesis of enzyme functional metal-organic framework for colorimetric detecting H 2 O 2 and ascorbic acid

In this work, a metal-organic frameworks material MIL-88 was prepared easily using solvent-thermal method, and was first found to have catalytic activities similar to those of biological enzymes such as catalase and peroxidase. The material was characterized by XRD, SEM, TEM, EDX, FT-IR techniques and an N2 adsorption method. It exhibited peroxidase-like activity through catalytic oxidation of the peroxidase substrate 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of H2O2, producing a blue-colored solution. Under optimal conditions, the absorbance at 652 nm is linearly correlated with the concentration of H2O2 from 2.0 × 10−6 mol/L to 2.03 × 10−5 mol/L (R2 = 0.981) with a detection limit of 5.62 × 10−7 mol/L (S/N = 3). More importantly, a sensitive and selective method for ascorbic acid detection was developed using this material as a catalyst. The analytical method for ascorbic acid detection was observed to have a linear range from 2.57 × 10−6 mol/L to 1.01 × 10−5 mol/L (R2 = 0.989) with a detection limit of 1.03 × 10−6 mol/L (S/N = 3). This work suggests MOFs have advantages of preparing biomimetic catalysts and extends applications of the functional MOFs in the field of biosensor.