NUIG4: A biocompatible pcu metal–organic framework with an exceptional doxorubicin encapsulation capacity

Abstract

Metal–organic frameworks (MOFs) are promising multifunctional porous materials for biomedical and environmental applications. Here, we report synthesis and characterization of a new MOF based on the tetrahedral secondary building unit [Zn₄O(CBAB)₃]_n (NUIG4), where CBABH₂ = 4-((4-carboxybenzylidene)amino)benzoic acid. NUIG4 belongs to the family of MOFs with primitive cubic pcu topology, being a rare example with 4-fold interpenetration. The pore architecture enables unprecedentedly high doxorubicin (DOX) loading capacity (1955 mg DOX/g NUIG4) with pH-controlled release. Solid-state NMR and ab initio modeling confirmed formation of aromatic π–π stacking interactions between DOX and the framework. Preliminary cell-line experiments suggested a protective effect of NUIG4 on healthy HDF cells against DOX toxicity. NUIG4 also displays potential for adsorptive small-molecule gas separation, with a BET surface area of 1358 m² g⁻¹ and high selectivity of 2.75 for C₂H₂ over CO₂.