Tuning FeⅡ/FeⅢ ratio by substituent regulation to enhance peroxidase-like activity of metal–organic framework for sensitive biosensing

Here, electron-donating and drawing substituents were introduced into MIL-88 (Fe) to regulate the electronic properties of the substituents. Benefiting from the influence of electron transfer and adsorption, the electron-donating (-NH2) substituent could significantly enhance POD-like activity of MIL-88 (Fe) due to the lowest energy change in rate determination step.