Porphyrin-Containing Metallacage with Precise Active Sites and Super Long-Term Stability as a Specific Peroxidase Mimic for Versatile Analyte Determination

Inspired by the architecture of single-atom catalysts, where the monodispersed metal atoms are widely distributed but stabilized by various coordination circumstances, the biomimetic design and synthesis of metalloporphyrin-containing nanocages have been demonstrated in this study. The nanocages were fabricated through a coordination-driven self-assembly process, and the Mn(III) porphyrin-based one was found to have exclusively peroxidase-like activity at pH 6.0 with neither oxidase nor catalase-like activity under the routine conditions. Benefiting from this, we demonstrated the wide applicability and convenient usage of an Mn(III)-containing supramolecular nanocage (Mn-PC) in the one-step detection of H₂O₂, sarcosine, and glucose through various oxidase-involved reactions, with a satisfactory detection limit and eligible specificity. Real samples including H₂O₂ in lens care solution, sarcosine in human urine, and glucose in human serum were also assayed, showing an adequate recovery rate. Such a specific activity originates from the super-consistent microstructure of each catalytic unit, which means that the active site of manganese porphyrin was "protected" by the confinement of the nanocage. This also helps to sustain the super long-term activity even after 545 days of storage. Furthermore, the intrinsic electronic structure of the Mn(III)-containing supramolecular nanocage endows the ability in electrochemical detection of H₂O₂ and glucose. Our smart design toward the supramolecular nanocages with a defined structure and quantity contributes to the construction of the ingenious sensing platform and has guiding significance for architectural design of nanozymes.