Upconversion nanorods anchored metal-organic frameworks via hierarchical and dynamic assembly for synergistic therapy

Heterogeneous materials made of metal-organic frameworks (MOFs) and optically active nanomaterials have attracted intensive interests in recent years due to their distinct physicochemical properties, but controllable fabrication of these materials remains challenging yet. In this work, we report a new strategy to in situ fabricate heterogeneous nanomaterials based on UiO-66-NH₂ and upconversion nanorods (UCNRs) via a hierarchical and dynamic assembly process. Core-satellite structured UiO-66-NH₂@UCNRs have been successfully fabricated, and the formation mechanism was thoroughly investigated by the combined use of scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. Our results revealed the involvement of three main stages: supramolecular assembly of UiO-66-NH₂ precursors with UCNRs, nucleation and growth of UiO-66-NH₂ crystal, and dynamic assembly with UCNRs accompanied by Ostwald ripening. Furthermore, based on the hereditary optical and porous features of the heterogeneous nanomaterials, an enhanced multimodal synergistic anticancer platform has been established by integrating near-infrared (NIR)-triggered photodynamic therapy (PDT) and pH-triggered anticancer drug delivery, as confirmed by cellular experiments. The present study provides a new avenue for developing advanced functional heterogeneous nanomaterials via the hierarchical and dynamic assembly strategy. [Figure not available: see fulltext.].