Enzyme Mimic Based on a Self-Assembled Chitosan/DNA Hybrid Exhibits Superior Activity and Tolerance

Nature has evolved enzymes with exquisite active sites that catalyze biotransformations with high efficiency. However, the exploitation of natural enzymes is often hampered by poor stability, and natural enzyme production and purification are costly. Supramolecular self-assembly allows the construction of biomimetic active sites, although it is challenging to produce such artificial enzymes with catalytic activity and stability that rival those of natural enzymes. We report herein a strategy to produce a horseradish peroxidase (HRP) mimic based on the assembly of chitosan with a G-quadruplex DNA (G-DNA)/hemin complex. A network-like morphology of the assembled nanomaterial was observed together with a remarkable enhancement of peroxidase activity induced by the chitosan and G-DNA components. The turnover frequency and catalytic efficiency of the enzyme-mimicking material reached or even surpassed those of HRP. Moreover, the catalytic complex exhibited higher tolerance than HRP to harsh environments, such as extremely low pH or high temperatures. In accord with the experimental and simulated results, it is concluded that the spatial distribution of the G-DNA and chitosan components and the exposure of the catalytic center may facilitate the coordination of substrates by the hemin iron, leading to the superior activity of the material. Our work provides a simple and affordable avenue to produce highly active and robust enzyme-mimicking catalytic nanomaterials.