Partially Reduced MIL-100(Fe) as a CO Carrier for Sustained CO Release and Regulation of Macrophage Phenotypic Polarization

Abstract

Carbon monoxide (CO) is a bioactive molecule with high potential as it shows promising efficacy for regulating inflammation. Materials capable of storing and delivering CO are of great potential therapeutic value. Although CO-releasing molecules (CORMs) have been developed to deliver CO, the short CO duration of minutes to 2 h confines their practical use. In this study, partially reduced MIL-100(Fe) as a new CO-releasing nanoMOF was developed and used for sustained CO release and macrophage (MA) phenotypic polarization regulation. MIL-100(Fe) was synthesized and mildly annealed in vacuum for partial reduction. When the annealing temperature was lower than 250 °C, less Fe(II) present in MIL-100(Fe) and the subsequent CO adsorption and desorption profiles displayed typical features of physisorption. While it was annealed at 250 °C, it showed about 20% of Fe(III) was reduced, which resulted in chemisorption of CO due to the high coordination affinity of Fe(II) to CO. The loading amount of CO was increased, and the CO release was prolonged for about 24 h. Furthermore, the CO release from this nanoMOF could alter the lipopolysaccharide (LPS)-induced macrophage from M1 to the alternative M2 phenotype and promoted the growth of endothelial cells (ECs) by paracrine regulation of MA. It can be envisioned as a promising CO-releasing solid for biomedical application.

An organic-organometallic CO-releasing material comprising 4,4′-bipyridine and molybdenum subcarbonyl building blocks

“…With one exception where a fluorescent probe was used, 59 all the studies used the Mb assay as the CO detection method. The standout feature of Mobpy is the amount of CO released (1.51 mmol g −1 in HEPES, 1.32 mmol g −1 in PBS), which is higher than that measured for Mo H pyz (1.05 mmol g −1 in HEPES), and much higher than that reported for CO-loaded MIL-88B-Fe and MIL-100-Fe MOFs (entries 5–7).…”

Recent advances in carbon monoxide-releasing nanomaterials

“…a) Structure of MIL-88B, b) SEM micrograph of NH 2 -MIL-88B, c) UHV-IR spectra of NH 2 -MIL-88B before and after CO incubation [ 105 ], Copyright 2013, Wiley-VCH. (C) Diagrammatic representation of the synthesis of CO@MIL-100(Fe) and the impact of released CO on MA over time [ 106 ]. Copyright 2022, ACS.…”

“…Yajun Weng and colleagues also successfully synthesized a highly crystalline Fe-based MOF, MIL-100(Fe), in aqueous phase at ambient temperature ( Fig. 7 C) [ 106 ]. Similar to MIL-88B, MIL-100(Fe) produces CUSs under vacuum thermal activation conditions, enabling direct binding of CO molecules.…”

Tricarbonyl-Pyrazine-Molybdenum(0) Metal–Organic Frameworks for the Storage and Delivery of Biologically Active Carbon Monoxide

“…For the CORM@SiO 2 system, the inaccessibility of some surface azido groups limited the degree of functionalization to 22% . To achieve higher CO payloads, porous or layered materials have been studied as nanocarriers. − The first report of this approach described the adsorption of CO on coordinatively unsaturated sites (CUS) in MIL-88B-Fe metal–organic frameworks (MOFs) . When the CO-loaded MOFs were immersed in phosphate buffered saline (PBS), framework degradation led to decarbonylation.…”