Hydrogen sulfide-activated DNA-engineered Au@Ag@Prussian blue nanoplatforms for cascade ROS amplification

Microenvironment-responsive catalytic nanoplatforms offer a promising route for amplifying reactive oxygen species (ROS), but their performance is often limited by insufficient H₂O₂ supply, glutathione (GSH)-mediated ROS scavenging, and limited colloidal stability under complex conditions. Accordingly, this study aimed to construct an H₂S-responsive cascade catalytic nanoplatform integrating DNA-mediated nanoparticle regulation with ROS-generating catalytic processes and to investigate its underlying catalytic mechanism. To achieve this goal, we developed a DNA sequence-engineered Prussian blue (PB)-coated Au@Ag nanoplatform (Au@Ag@PB) using A15-CpG DNA as a surface-regulating ligand, in which the adenine-rich A15 segment facilitated surface association with Au@Ag and contributed to colloidal stabilization, whereas the CpG-containing segment provided an oligonucleotide component for stimulus-responsive release. Among the tested DNA sequences, A15-CpG exhibited favorable colloidal behavior and supported relatively homogeneous Au@Ag@PB formation. Upon H₂S exposure, the PB shell decomposed to release Fe²⁺ for Fenton-mediated ·OH generation, while sulfide-mediated Ag-shell etching increased the accessibility of the Au component. The more accessible Au component exhibited glucose oxidase-like activity and promoted glucose-associated H₂O₂ generation, while Fe-mediated Fenton reactions generated ·OH, as supported by fluorescence and EPR measurements. Meanwhile, the nanoplatform exhibited GSH-depleting capability in cell-free assays and enabled H₂S-responsive release of surface-associated DNA. In vitro experiments showed preliminary cytocompatibility toward MRE cells, increased intracellular ROS accumulation under NaHS-triggered conditions, and concentration-dependent inhibition of 4T1 cells. Collectively, these results highlight DNA sequence engineering as a surface-regulation strategy for constructing H₂S-responsive cascade catalytic nanoplatforms with integrated colloidal regulation and ROS-amplifying catalytic functions.