Assembling of Gold Nanoparticles in Core-Shell Zeolite Imidazolate Framework Crystals for In Situ Electrochemical Detection of H₂O₂ Released from Living Cells

The quantification of hydrogen peroxide (H2O2), a vital biomarker in pathogenesis released from live cells, is of importance to life science. This work presents a method to assemble gold nanoparticles (AuNPs) in core-shell zeolite imidazolate framework (ZIF) crystals by the direct growth of ZIF-67 on ZIF-8 seeds (AuNPs/ZIF-8@ZIF-67). With a large surface, abundant catalytic sites, enhanced conductivity, and good dispersity of components, the AuNPs/ZIF-8@ZIF-67-modified glassy carbon electrode (AuNPs/ZIF-8@ZIF-67/GCE) reveals excellent catalytic activity for the electrochemical reduction of H2O2. The modified electrode exhibits a wide linear range of 0.05-120 mu M and a low detection limit of 0.016 mu M (S/N = 3) with excellent selectivity, stability, and reproducibility. The corresponding electrochemical sensor has been successfully used for the practical detection of H2O2 released from living human embryonic kidney 293 (HEK293) cells and nonmetastatic breast cancer (MCF-7) cells under optimal conditions. This sensor demonstrates the potential for in situ detection applications in complicated biological systems.