Long-Term Antioxidant Metal–Organic Frameworks

Abstract

Free radicals produced during metabolism induce effects, such as cell damage and cancer, because of their high reactivity. Although antioxidants in food products can eliminate free radicals, they are expelled within a relatively short period of time after serving their function. In this study, we investigated the possibility of using metal−organic frameworks (MOFs) with antioxidants as their ligands. Metal−organic frameworks are crystalline polymers with repetitively coordinated ligands and metal centers. We assume that once antioxidant-based MOFs are ingested, ligands are released on a long-term basis during the process of chemical and physical disintegration. To evaluate their eligibility, we established criteria for biocompatibility, particle size, and long-term antioxidant effects. For biocompatibility, we treated cells with various concentrations of MOFs and their precursors followed by a water-soluble tetrazolium 8 (WST-8) assay. The particle size distribution was analyzed using TEM and ImageJ software, and the antioxidant release was quantified using UV−vis spectroscopy. We concluded that Fe-based FeTHQ with the antioxidant tetrahydroxy-1,4-benzoquinone (THQ) as its ligand is the most effective long-term antioxidant with its effect lasting up to 7 days. Furthermore, microwave synthesis of FeTHQ was conducted to produce more suitable particles for in vivo antioxidant applications.