Increasingly intricate in their multilevel multiscale microarchitecture, metamaterials with unique physical properties are challenging the inherent constraints of natural materials. Their applicability in the nanomedicine field still suffers because nanomedicine requires a maximum size of tens to hundreds of nanometers; however, this size scale has not been achieved in metamaterials. Therefore, "nano-metamaterials," a novel class of metamaterials, are introduced, which are rationally designed materials with multilevel microarchitectures and both characteristic sizes and whole sizes at the nanoscale, investing in themselves remarkably unique and significantly enhanced material properties as compared with conventional nanomaterials. Microarchitectural regulation through conventional thermodynamic strategy is limited since the thermodynamic process relies on the frequency-dependent effective temperature, Teff (ω), which limits the architectural regulation freedom degree. Here, a novel dual-kinetic control strategy is designed to fabricate nano-metamaterials by freezing a high-free energy state in a Teff (ω)-constant system, where two independent dynamic processes, non-solvent induced block copolymer (BCP) self-assembly and osmotically driven self-emulsification, are regulated simultaneously. Fe3+ -"onion-like core@porous corona" (Fe3+ -OCPCs) nanoparticles (the products) have not only architectural complexity, porous corona and an onion-like core but also compositional complexity, Fe3+ chelating BCP assemblies. Furthermore, by using Fe3+ -OCPCs as a model material, a microstructure-biological performance relationship is manifested in nano-metamaterials.
Keywords: T1-weighted magnetic resonance imaging; block copolymer self-assembly; hierarchical structure; kinetic control; nano-metamaterials.
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