Diatomic active sites nanozymes: Enhanced peroxidase-like activity for dopamine and intracellular H2O2 detection

Considering intracellular hydrogen peroxide (H2O2) plays pivotal roles in the regulation of serial biological processes, the in-situ detection of intracellular H2O2 has attracted an extensive attention. In the present work, an atomically dispersed diatomic active sites Nanozymes (FeN3/PtN4-single-atom nanozymes (SAzyme)) was prepared exhibiting enhanced peroxidase-like activity. The obvious synergistic effect between Fe-Pt heteronuclear diatomic active sites was confirmed by series of characterization and density functional theory (DFT). The peroxidase-like activity of Fe-sites could be substantially enhanced by the bonded Pt-sites via the modulation effect. As a consequence, the gap between the d-band centre (εd) of Fe 3d orbitals and the Fermi energy level was narrowed and the electronic interaction could be strengthened, leading to a lower free energy barrier and a lower activation energy as well as fortified metal–O bonding in the kinetic pathway. Therefore, the constructed FeN3/PtN4-SAzyme exhibited higher peroxidase-like activity than that of FeN4-SAzyme. The FeN3/PtN4-SAzyme-assisted oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) facilitated the colorimetric detection of dopamine (DA), an important biomolecule. The linear detection range and limit of detection (LOD) of DA and H2O2 were 1–10 µM, 0.01–1.0 mM and 0.109 µM, 7.97 µM, respectively. In addition, the constructed SAzymes were also applied for the in-situ detection of intracellular H2O2, expanding the application scope of the newborn SAzymes.