Metal‐Organic Frameworks: Edible Frameworks

Abstract

Metal‐organic frameworks (MOFs)—porous materials composed of organic linkers connected by metal ion or metal cluster joints—are increasingly being investigated as intravenous drug delivery vectors, as a consequence of their high molecular storage capacities, ease of functionalization, amenability to formulation, and, most importantly, the potential for MOFs with very low toxicity to be prepared. For oral administration of MOF‐based treatments, it would be most desirable to prepare materials that are suitable for human consumption, that is, edible MOFs . Currently, very little information on the safety and toxicity of MOFs is available, and so chemists must make inferences based on the properties of the precursor materials. This chapter discusses the numerous parameters that must be considered in preparing edible MOFs, including (i) available synthetic methods, (ii) desirable solvents, (iii) the metal ion(s) of choice, and (iv) the numerous categories of ligands available. Examples of porous materials that may be consumable and have interesting structures and properties, covering MOFs composed of naturally occurring linkers such as endogenous diacids, amino acids, peptides, nucleobases, and carbohydrates, as well as those prepared from petrochemically derived synthetic molecules, are provided. Finally, conclusions and suggestions for best practice are offered along with an outlook on the future of edible MOFs.

Calcium l-Lactate Frameworks as Naturally Degradable Carriers for Pesticides

“…The size, geometry, and functionality of the organic units and the variability of the metal ions have led to the discovery of more than 20 000 MOFs with a wide range of applications in gas separation, storage, and catalysis . However, the majority of MOFs reported to date are based on transition metal ions and organic linkers derived from petrochemical sources, and their toxicity has precluded many of important applications requiring eco-friendly (environmentally friendly) materials, such as applications in the food industry, biomedicine, and agriculture …”

“…Preparation of MOFs from eco-friendly metal ions such as Ca 2+ and nontoxic, naturally occurring linkers would expand the scope of applications. , However, their synthesis remains a challenge, and there have been no reported examples of such Ca 2+ -based MOFs as porous materials. This challenge is due to the multiplicity of coordination geometries and high coordination number of Ca 2+ ions and the flexibility of naturally occurring organic linkers, thus resulting in dense, nonporous structures. , …”

“…The porosity of MOF-1201 along with its environmentally friendly composition (Ca 2+ , lactate, and acetate) allowed us to explore the potential application of these MOFs in the agriculture industry, where nontoxicity and human and environmental benignity are the most important requirements for a material to be used. , Here we demonstrated the use of MOF-1201 as a solid formulation for volatile liquid fumigants.…”

Lectin-Recognizable MOF Glyconanoparticles: Supramolecular Glycosylation of ZIF-8 Nanocrystals by Sugar-Based Surfactants

“…36−40 In this sense, advances oriented to the incorporation of such functionalities in MOFs and MOF-containing composites have been focused on replacing usual organic linkers with carbohydrate supramolecular assemblies, such as cyclodextrins (CDs), yielding edible porous materials, the so-called CD-MOFs. 41−44…”

“…Research efforts on this matter are often referred to as glyconanotechnology, a term popularized by Penadés and co-workers . Great strides in glyconanotechnology have been made as a result of the creation of different bioactive glyconanostructures for various health-related applications, such as drug delivery, gene therapy, pathogen detection, toxin inhibition, and lectin-based biosensors. − In this sense, advances oriented to the incorporation of such functionalities in MOFs and MOF-containing composites have been focused on replacing usual organic linkers with carbohydrate supramolecular assemblies, such as cyclodextrins (CDs), yielding edible porous materials, the so-called CD-MOFs. − …”