Abstract
Artificial enzymes with modulated enzyme-mimicking activities of natural systems represent a challenge in catalytic applications. Here, we show the creation of artificial Cu metalloenzymes based on the generation of Cu nanoparticles in an enzyme matrix. Different enzymes were used, and the structural differences between the enzymes especially influenced the controlled the size of the nanoparticles and the environment that surrounds them. Herein, we demonstrated that the oxidase-like catalytic activity of these copper nanozymes was rationally modulated by enzyme used as a scaffold, with a special role in the nanoparticle size and their environment. In this sense, these nanocopper hybrids have confirmed the ability to mimic a unique enzymatic activity completely different from the natural activity of the enzyme used as a scaffold, such as tyrosinase-like activity or as Fenton catalyst, which has extremely higher stability than natural mushroom tyrosinase. More interestingly, the oxidoreductase-like activity of nanocopper hybrids was cooperatively modulated with the synergistic effect between the enzyme and the nanoparticles improving the catalase activity (no peroxidase activity). Additionally, a novel dual (metallic and enzymatic activity) of the nanozyme made the highly improved catechol-like activity interesting for the design of 3,4-dihydroxy-l-phenylalanine (l-DOPA) biosensor for detection of tyrosinase. These hybrids also showed cytotoxic activity against different tumor cells, interesting in biocatalytic tumor therapy.
Highlights
One of the key advantages of enzymes is the high selectivity and activity against a particular reaction; outside of cells, they present low activity against non-natural substrate and low stability in different media than biological environment, which are important drawbacks for commercial applications
Different enzymes which involved different conformational structures, dimeric or multimeric complexes, or even introducing post-translational modifications were used in the preparation of enzyme/CuNP hybrids
The difference between enzymes, where we can use three different lipases with a particular catalytic mechanism, and the use of a supramolecular tetrameric catalase demonstrates the important effect of the structure on the final catalytic properties as nanozymes
Summary
One of the key advantages of enzymes is the high selectivity and activity against a particular reaction; outside of cells, they present low activity against non-natural substrate and low stability in different media than biological environment, which are important drawbacks for commercial applications. Nanozymes have emerged in the last years as one of the most interesting alternatives to natural enzymes, and even conventional enzyme mimics, as artificial biocatalytic tools for decontamination, biosensor, and biomedical applications.[1−14]. At this point, nanozymes show unique advantages over natural enzymes offering robustness to harsh environments, high stability, long-term storage, ease of modification, and lower manufacturing cost than protein enzymes. We demonstrate how to modulate the particular enzyme-like activity of novel copper nanohybrids, formed by copper nanoparticles (as active sites) created in a protein environment (as a scaffold), where precisely the used enzyme plays a fundamental role. A synergistic effect between the enzyme as a scaffold and the CuNPs was observed for an enhanced catalase activity
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