Development of Supramolecular Calix[4]arene-MCM-Based Nanomaterials Doped with CuNPs: An Inorganic–Organic Hybrid Recyclable Nanoenzyme as a Potent Peroxidase and Oxidase Mimic

An inorganic–organic hybrid nanomaterial, Cu@MCMCal, was synthesized by immobilizing p-tert-butyl calix[4]arene on to mesoporous silica followed by incorporation of CuNPs. The synthesized nanomaterial was characterized extensively using various analytical techniques such as FT-IR, UV–Vis spectroscopy, TEM, PXRD, XPS, Cu LMM Auger, BET, and TGA analyses. The hybrid nanomaterial was evaluated for its catalytic performance toward peroxidase-like activity using 3,3′,5,5′-tetramethylbenzidine (TMB) and o-phenylenediamine (OPD) as a substrate at room temperature at pH 4.5 in acetate buffer and pH 7.4 in PBS buffer, respectively. Enzyme kinetics was performed for both the substrates using the Michaelis–Menten steady-state kinetics and the Lineweaver–Burk plot to determine the catalytic affinity. Based on the kinetic measurements, the values of the Km for TMB and OPD were found to be 0.661 ± 0.143 and 0.606 ± 0.061 mM, respectively. The hybrid nanoenzyme also exhibits the oxidase-like activity using dopamine as a substrate at pH 7.4 in PBS buffer. The Cu@MCMCal nanomaterial acted as a nanoenzyme, efficient for catalysis toward oxidation reactions with better cost effectiveness and improved stability and recyclability as compared to biological enzymes. Therefore, a promising, stable, efficient, and robust nanoenzyme has been development for oxidation reactions.