Bioinspired Diffusion-Limited Silicification in Coacervate Assemblies Enables Smart Nanotoroids for Deep and Sensitive Tumor Penetration

Controlling the self-assembly of mesoporous materials beyond equilibrium remains a fundamental challenge. Conventional templating systems form ordered structures through energy-minimizing coassembly but lack the kinetic and spatial freedom required to produce asymmetric or topologically complex architectures. Here, we report a bioinspired coacervate-directed silicification strategy that enables diffusion-limited and spatially asymmetric condensation within soft templates, yielding ordered hexagonal mesoporous nanotoroids. In this system, poly(acrylic acid) (PAA) electrostatically associates with the cationic surfactant cetyltrimethylammonium bromide (CTAB), driving liquid–liquid phase separation and forming disc-like coacervate assemblies. Reaction-diffusion imbalance across the inner and outer interfaces within these templates induces asymmetric silicification, driving an interior collapse and toroidal self-transformation. By tuning PAA concentration, the diffusion-condensation kinetics can be precisely modulated, allowing programmable control over collapse dynamics and final topology, with enlarged central cavities (14–71 nm) and reduced rim thickness (15–35 nm). These nanotoroids exhibit uniform sub-100 nm size, high surface area (846 m 2 g –1 ), and abundant mesopores (∼2.0 nm). The nanotoroids (rim thickness ∼15 nm, height ∼40 nm) display markedly prolonged blood circulation, enhanced tumor accumulation (+173%), improved vascular extravasation, and deeper intratumoral penetration, while reducing hepatic and splenic uptake by 19% and 14%, respectively, compared with spherical analogues. These combined advantages translate into potent antitumor efficacy in both subcutaneous and spinal metastasis models. This work establishes a new paradigm for sol–gel topology control by bridging reaction-diffusion dynamics with bioinspired silicification based on the chemistry of LLPS (liquid–liquid phase separation), thereby unlocking the untapped biomedical potential of toroidal topologies that were rarely accessible.