Hemin immobilized into metal–organic frameworks as an electrochemical biosensor for 2,4,6-trichlorophenol

Hemin immobilized into copper-based metal–organic frameworks was successfully prepared and used as a new electrode material for sensitive electrochemical biosensing. X-ray diffraction patterns, Fourier transform infrared spectra, scanning electron microscopy, UV–vis absorption spectroscopy, and cyclic voltammetry were used to characterize the resultant composites. Due to the interaction between the copper atom groups and hemin, the constrained environment in Cu-MOF-74 acts as a matrix to avoid the dimerization of enzyme molecules and retain its biological activity. The hemin/Cu-MOF composites demonstrated enhanced electrocatalytical activity and high stability towards the oxidation of 2,4,6-trichlorophenol. Under optimum experimental conditions, the sensor showed a wide linear relationship over the range of 0.01–9 μmol L−1 with a detection limit (3σ) of 0.005 μmol L−1. The relative standard deviations were 4.6% and 3.5% for five repeated measurements of 0.5 and 5 μmol L−1 2,4,6-trichlorophenol, respectively. The detection platforms for 2,4,6-trichlorophenol developed here not only indicate that hemin/Cu-MOF-74 possesses intrinsic biological reactivity, but also enable further work to be conducted towards the application of enzyme-containing metal–organic frameworks in electrochemical biosensors.