Tailoring Square-Shaped 2D Mesoporous Nanosheets via an Interface-Confined Anisotropic Assembly Strategy.

Despite considerable advancements in the synthesis of two-dimensional (2D) mesoporous nanomaterials, achieving precise control over their components, morphology, lateral dimension, and thickness remains a formidable challenge. Here, we report a rational interface-confined anisotropic assembly strategy that enables the synthesis of square-shaped 2D mesoporous nanosheets with finely tunable features including compositions (metal ion-doped mesoporous polydopamine or silica), lateral dimensions (100-200 nm), thicknesses (14-25 nm), and in-plane mesopore sizes (8-20 nm). In this strategy, truncated rhombic dodecahedral ZIF-8 metal-organic framework (MOF) nanoparticles serve as seeds to direct the selective assembly of mesoporous micelles onto their six {100} facets. The geometric confinement of these square facets guides the interfacial organization of micelles into 2D sheet-like structure, faithfully inheriting the square geometry. Following etching of the ZIF-8 seeds, the resulting nanosheets preserve their well-defined square-shaped 2D morphology and mesoporous architecture. This versatile approach enables the fabrication of diverse 2D mesoporous tunable structural attributes and metal-ion dopants. As a proof of concept, mPDA-Zn2+/Fe2+ nanosquares, featuring a uniform 2D architecture, near-infrared (NIR) photothermal properties, and Fenton-like catalytic activity, demonstrate synergistic therapeutic effects. Compared to conventional spherical analogs (1.08 × 10-8 M/s), these nanosquares (2.11 × 10-8 M/s) achieve nearly doubled maximum reaction rates and achieved remarkable tumor inhibition of up to 90%. Overall, this study establishes a novel approach for the precise engineering of 2D mesoporous nanosquares with controllable parameters, unlocking new opportunities for applications in biomedicine and beyond.