Interfacial chemistry governs nanoparticle self-sorting during biomimetic crystallization.

Biominerals comprise composite crystals in which organic constituents are spatially organized within mineral matrices with exquisite precision, giving rise to hierarchically ordered architectures. Despite extensive efforts, achieving precise control over organic-inorganic interactions to construct biomimetic composite materials with programmable composition and spatial organization remains a major challenge. Here we show that diblock copolymer nanoparticles with distinct compositions and dimensions-resembling pseudo-proteins-undergo spontaneous self-sorting during occlusion within growing calcite crystals, yielding artificial biominerals in which two nanoparticle populations are selectively localized in distinct crystalline domains. Using in situ monitoring techniques and atomic force microscopy, we demonstrate that this self-sorting process arises from nanoparticle surface chemistry, which leads to differing polymer-mineral interfacial interactions. Moreover, the resulting composite crystals exhibit spatiotemporal release of the occluded species, highlighting the potential for advanced delivery systems. More broadly, self-sorting occlusion establishes a conceptual framework for understanding the spatial organization of organic components in biominerals and provides a versatile strategy for the rational design of next-generation biomimetic materials.