Spatially Ordered Dual-Atom Nanozymes for Mimicking Substrate-Induced Conformational Locking in Natural Enzymes

Natural metalloenzymes achieve exceptional catalytic efficiency and specificity through substrate-induced conformational locking (SCL) across bimetallic sites. However, most nanozymes lack such adaptive microenvironments and dynamic regulatory capabilities. We reported a spatially ordered bimetallic nanozyme, o-FePd DAN, with a Cl-FeN₃C-PdN₃ catalytic center that emulated the SCL mechanism through directional electron transfer (DET) and axial microenvironment reconfiguration. Density functional theory (DFT) calculations showed that the Fe-Pd configuration provides optimal H₂O₂ adsorption, the lowest O-O dissociation energy, and enhanced activation of reactive oxygen species (ROS). Meanwhile, operando X-ray absorption spectroscopy reveals the formation of a bridged structure at the bimetallic site during catalysis, establishing a dynamic charge-transfer pathway that switches the dominant reaction from ROS-mediated oxidation to a DET process driven by the bridged structure. This adaptive electron modulation arises from d-orbital hybridization and the emergence of new active states near the Fermi level in the Cl-FeN₃C-PdN₃ site. Furthermore, o-FePd DAN is integrated into a three-channel visual origami sensing (Tc-VOS) platform for multichannel genotyping of human papillomavirus (HPV) subtypes. This work demonstrates a strategy for constructing spatially ordered bimetallic DANs that reproduce the SCL effect of natural enzymes and establish a dynamic, conformationally adaptive catalytic mechanism for nanozyme design.