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 (epsilon(d)) 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 mu M, 0.01-1.0 mM and 0.109 mu M, 7.97 mu M, 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.

Automated summary

In this study, atomically dispersed diatomic active sites nanozymes with enhanced peroxidase-like activity were successfully prepared, and the synergistic effect between Fe-Pt heteronuclear diatomic active sites was confirmed. The nanozymes showed a wide detection range and low detection limit for dopamine and hydrogen peroxide, and could be used for in-situ detection of intracellular hydrogen peroxide.