A Co(II)–organic framework and peroxidase mimetic Hemin@metal–organic framework and its application in the colorimetric analysis of glucose

Abstract

A Co(II)-organic framework (Co-MOF), [Co₃(3,5-bimpy)₂(5-cpia)₂(H₂O)₂], was constructed via the hydrothermal reaction of 3,5-bis(1-imidazoly)pyridine (3,5-bimpy) and 5-(2′-carboxylphenoxy)isophthalic acid (5-H₃cpia). The Co-MOF possessed a three-dimensional (3D) porous architecture with the porosity of 22.4% per unit volume. The Co-MOF@Hemin composite was further constructed via the encapsulation of Hemin into the Co-MOF material. The constructed Co-MOF@Hemin exhibited satisfactory peroxidase-like activity through catalytic oxidation of the colorless peroxidase substrate 3,3,5,5-tetramethylbenzidine (TMB) to a blue-colored oxTMB in the presence of H₂O₂. Hence, the detection of H₂O₂ was achieved with a wide linear range from 0.005 to 0.5 mM (R² = 0.992) and a low detection limit of 1.26 μM. More importantly, the peroxidase-like Co-MOF@Hemin was suitable for the sensitive and selective detection of glucose under the presence of glucose oxidase (GOx), which reduced O₂ to H₂O₂. This analytical procedure for the detection of glucose had a linear range from 0.3 to 3 mM (R² = 0.997), with a detection limit of 49 μM. The experimental results display the broad application prospects of the enzyme-based MOFs in green and selective targets analyses.