Rational Coordination Modification of MOF-808-His-Tyr-Cu: Dual Oxidase and Peroxidase Mimics, and Catalytic Applications.

It is still a challenge to rationally design and develop new nanozymes showing high activity and selectivity, in comparison with that of the natural bioenzymes in catalysis. Inspired by the active Cu sites in native oxidase and the intrinsic electron transfer pathway between Cu2+/Cu+, herein, the complex composed of Cu(I), histidine (His) and tyrosine (Tyr) was precisely encapsulated into the pocket of MOF-808 via the chemical interactions, and the resulting MOF-808-His-Tyr-Cu nanozyme is able to produce H2O2 by 2e- reduction of oxygen with methanol serving as electron donor, representing the characteristic oxidase-like activity. The as-generated H2O2 participated in situ in the cascade catalytic oxidation of o-phenylenediamine (OPD), which is a process that is utilized in the sensing analysis of OPD. These MOF-808-His-Tyr-Cu also exhibit excellent peroxidase (POD)-like catalytic ability in an aqueous system, and, based on that, a colorimetric method for the detection of total antioxidant capacity (TAC) was developed using a smartphone platform. The nanoenzyme catalytic mechanism was revealed, and the positive roles of Cu(I) sites, His, and Tyr work well in the enhanced enzyme like activities. Moreover, MOF-808-His-Tyr-Cu shows good oxidase mimics and works well in the catalytic generation of H2O2. Its POD-like activity also guarantees widespread prospective applications in the biocatalytic engineering and biosensing analyses.