Dual nanozyme based on ultrathin 2D conductive MOF nanosheets intergraded with gold nanoparticles for electrochemical biosensing of H2O2 in cancer cells

The development of facile, rapid and cost-effective strategies for sensitive detection of cancer biomarkers in human samples is of great significance for early diagnosis of malignant tumors related diseases. In this work, we develop a high-performance electrochemical biosensor based on highly active dual nanozyme amplified system, i.e., ultrathin two-dimension (2D) conductive metal-organic framework (C-MOF) nanosheets (NSs) decorated with high-density ultrafine gold nanoparticles (Au-NPs), and explore its application in sensitive detection of cancer biomarker H2O2 in live cells. The C-MOF NSs {i.e., Cu-HHTP (HHTP = 2,3,6,7,10,11-hexahydroxytriphenylene)-NSs} provide large surface area and abundant active open metal sites (Cu-O4), which could improve the catalytic activity of Cu-HHTP-NSs towards H2O2. Moreover, abundant exposed O atoms also serve as anchor sites for the deposition of high-density ultrafine Au-NPs (∼3 nm) without agglomeration. Owing to the synergistic contributions of high catalytic activity of Cu-HHTP-NSs and Au-NPs as well as their unique structural and electrical properties, the as-prepared nanohybrid modified electrode exhibits good sensing performances to H2O2 with an extremely low detection limit of 5.6 nM (3σ rules) and a high sensitivity of 188.1 μA cm-2 mM-1. Furthermore, the proposed nanozymatic electrochemical biosensor has been applied in real-time tracking H2O2 released from different human colon cells to identify colon cancer cells from normal colon epithelial cell, which demonstrates its great prospect for early diagnosis and management of various cancer diseases.