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

Abstract

The high catalytic activity of Cu-based nanozymes mainly depends on the efficient Fenton-like reaction of Cu⁺/ H₂O₂, but Cu⁺ cannot exist stably. Trying to find a material that can stably support Cu⁺ while promoting the electron cycle of Cu²⁺/Cu⁺ still faces serious challenges. C₆₀ 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 C₆₀-doped Cu⁺-based nanozyme (termed as C₆₀-Cu-Bpy) by loading high catalytic active site Cu⁺ onto C₆₀ 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 C₆₀-Cu-Bpy. Significantly, the C₆₀-Cu-Bpy exhibited superior peroxidase-like activity during the catalytic oxidation of 3,3',5,5'-tetramethylbenzidine (TMB). Then, the catalytic mechanism of C₆₀-Cu-Bpy as peroxidase was elucidated in detail, mainly benefiting from the dual function of C₆₀. On the one hand, C₆₀ acted as a carrier to directly support Cu⁺, which has the ability to efficiently decompose H₂O₂ to produce reactive oxygen species. The other was that C₆₀ acted as an electron buffer, contributing to promoting the Cu²⁺/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 C₆₀-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.

Keywords: Bleomycin; C60-Cu-Bpy; Colorimetric detection; Nanozymes; Peroxidase-like activity.