The selective enhancement of catalytic activity is a challenging task, as catalyst modification is generally accompanied by both desirable and undesirable properties. For example, in the case of the direct synthesis of hydrogen peroxide, Pt on Pd improves hydrogen conversion, but lowers hydrogen peroxide selectivity, whereas Au on Pd enhances hydrogen peroxide selectivity but decreases hydrogen conversion. Toward an ideal catalytic property, the development of a catalyst that is capable of improving H-H dissociation for increasing H₂ conversion, whilst suppressing O-O dissociation for high H₂O₂ selectivity would be highly beneficial. Pd-core AuPt-bimetallic shell nanoparticles with a nano-sized bimetallic layer composed of Au-rich or Pt-rich content with Pd cubes were readily prepared via the direct seed-mediated growth method. In the Pd-core AuPt-bimetallic shell nanoparticles, Au was predominantly located on the {100} facets of the Pd nanocubes, whereas Pt was deposited on the corners of the Pd nanocubes. The evaluation of Pd-core AuPt-bimetallic shell nanoparticles with varying Au and Pt contents revealed that Pd-core AuPt-bimetallic shell that was composed of 2.5 mol% Au and 5 mol% Pt, in relation to Pd, exhibited the highest H₂O₂ production rate (914 mmol H₂O₂ g_metal⁻¹ h⁻¹), due to the improvement of both H₂O₂ selectivity and H₂ conversion.

Diverse connective tissues exhibit hierarchical anisotropic structures that intricately regulate homeostasis and tissue functions for dynamic immune response modulation. In this study, remotely manipulable hierarchical nanostructures are tailored to exhibit multi-scale ligand anisotropy. Hierarchical nanostructure construction involves coupling liganded nanoscale isotropic/anisotropic Au (comparable to few integrin molecules-scale) to the surface of microscale isotropic/anisotropic magnetic Fe₃O₄ (comparable to integrin cluster-scale) and then elastically tethering them to a substrate. Systematic independent tailoring of nanoscale or microscale ligand isotropy versus anisotropy in four different hierarchical nanostructures with constant liganded surface area demonstrates similar levels of integrin molecule bridging and macrophage adhesion on the nanoscale ligand isotropy versus anisotropy. Conversely, the levels of integrin cluster bridging across hierarchical nanostructures and macrophage adhesion are significantly promoted by microscale ligand anisotropy compared with microscale ligand isotropy. Furthermore, microscale ligand anisotropy dominantly activates the host macrophage adhesion and pro-regenerative M2 polarization in vivo over the nanoscale ligand anisotropy, which can be cyclically reversed by substrate-proximate versus substrate-distant magnetic manipulation. This unprecedented scale-specific regulation of cells can be diversified by unlimited tuning of the scale, anisotropy, dimension, shape, and magnetism of hierarchical structures to decipher scale-specific dynamic cell-material interactions to advance immunoengineering strategies.