Nanoscale Zr-Based MOFs with Tailorable Size and Introduced Mesopore for Protein Delivery

Introduction of large pore in the primitive microporous metal–organic frameworks (MOFs) with tailorable particle size can endow them with desired properties for potential applications in the intracellular delivery of membrane-impermeable proteins. However, no research is found to focus on this topic until now. Herein, a monocarboxylic acid (MA) and organic base comodulation strategy is developed to synthesize the hierarchically porous UiO-66 nanoparticles. MA of dodecanoic acid is utilized to control the pore size while trimethylamine (TEA) plays a key role in modulating the nucleation of crystallization to regulate the particle size. In comparison with microporous UiO-66, a model protein of cytochrome c (Cyt c) could be efficiently loaded into the mesoporous MOFs (mesoMOFs). The size-dependent cellular uptake is also evaluated, and it is verified that mesoMOFs with particle size of 90 nm could be endocytosed into living cells with highest efficiency. These outstanding merits enable the current mesoMOFs not only to exhibit efficient encapsulation of Cyt c but also facilitate the protein delivery into the cytosol and subsequent endosomal escape. Given the exceptional chemical stability, hierarchically porous structure as well as tunable particle size, the elaborated mesoUiO-66 nanoparticles might offer a promising platform for a variety of biomedical applications.