Postsynthetic Modifications of Iron-Carboxylate Nanoscale Metal−Organic Frameworks for Imaging and Drug Delivery

TLDR

Fe(III)-carboxylate NMOFs with MIL‑101 structure were synthesized by microwave‑assisted solvothermal reaction, characterized by SEM, PXRD, nitrogen adsorption, TGA, and EDX, and functionalized by partially replacing terephthalic acid with 2‑amino terephthalic acid to introduce amine sites for cargo attachment while preserving the framework. Proof‑of‑concept experiments showed that BODIPY dye and an ethoxysuccinato‑cisplatin prodrug could be incorporated into the NMOFs, released upon framework degradation with a rate tunable by silica coating, and that the resulting nanocarriers enabled optical imaging and anticancer activity in HT‑29 colon adenocarcinoma cells.

Abstract

Fe(III)-carboxylate nanoscale metal−organic frameworks (NMOFs) with the MIL-101 structure were synthesized using a solvothermal technique with microwave heating. The ∼200 nm particles were characterized using a variety of methods, including SEM, PXRD, nitrogen adsorption measurements, TGA, and EDX. By replacing a percentage of the bridging ligand (terephthalic acid) with 2-amino terephthalic acid, amine groups were incorporated into the framework to provide sites for covalent attachment of biologically relevant cargoes while still maintaining the MIL-101 structure. In proof-of-concept experiments, an optical contrast agent (a BODIPY dye) and an ethoxysuccinato-cisplatin anticancer prodrug were successfully incorporated into the Fe(III)-carboxylate NMOFs via postsynthetic modifications of the as-synthesized particles. These cargoes are released upon the degradation of the NMOF frameworks, and the rate of cargo release was controlled by coating the NMOF particles with a silica shell. Potential utility of the new NMOF-based nanodelivery vehicles for optical imaging and anticancer therapy was demonstrated in vitro using HT-29 human colon adenocarcinoma cells.