Rational design of cuprofullerene bipyridine nanozyme with high peroxidase-like activity for colorimetric sensing of bleomycin.

The high catalytic activity of Cu-based nanozymes mainly depends on the efficient Fenton-like reaction of Cu/ HO, but Cu cannot exist stably. Trying to find a material that can stably support Cu while promoting the electron cycle of Cu/Cu still faces serious challenges. C is expected to be an ideal candidate to solve this problem due to its unique structure and rich physicochemical properties. Here, we designed and synthesized a C-doped Cu-based nanozyme (termed as C-Cu-Bpy) by loading high catalytic active site Cu onto C and coordinating with 2,2'-bipyridine (Bpy). The single crystal diffraction analysis and a series of auxiliary characterization technologies were used to demonstrate the successful preparation of C-Cu-Bpy. Significantly, the C-Cu-Bpy exhibited superior peroxidase-like activity during the catalytic oxidation of 3,3',5,5'-tetramethylbenzidine (TMB). Then, the catalytic mechanism of C-Cu-Bpy as peroxidase was elucidated in detail, mainly benefiting from the dual function of C. On the one hand, C acted as a carrier to directly support Cu, which has the ability to efficiently decompose HO to produce reactive oxygen species. The other was that C acted as an electron buffer, contributing to promoting the Cu/Cu cycle to facilitate the reaction. Furthermore, a colorimetric sensor for the quantitative analysis of bleomycin was established based on the principle of bleomycin specific inhibition of C-Cu-Bpy peroxidase-like activity, with satisfactory results in practical samples. This study provides a new strategy for the direct synthesis of Cu-based nanozymes with high catalytic performance.