Metal‐Organic‐Frameworks as Contrast Agents in Magnetic Resonance Imaging

Abstract

Metal-organic-frameworks (MOFs) are used either as drug carrying substrate for drug delivery or contrast agent for magnetic resonance imaging (MRI). MOFs are also playing a major role in harnessing dual or multiple modalities in therapeutic and diagnostic applications as a combined platform for both drug delivery and MRI contrast agents either as a T 1 -or T 2 -or combined T 1 -and T 2 -contrast agents for MRI image enhancement. This article presents an overview of the recent development of the modified and unmodified MOFs being used as MRI contrast agents and describes their biological evaluations, e.g., biocompatibility, bio-toxicity, in vitro and in vivo MRI cell imaging, and MRI image enhancement in animals. It illustrates vast diversities and complexities in developing these materials through complex designs and syntheses, types of MOFs being used, examinations of these MOFs-based materials for possible MRI contrast agents, types of MRI contrast agents, their functionalities and mechanism, in situ and in vivo MRI in cells and animals, and ranges of biological evaluations on the MOFs-based MRI contrast agents. Perspectives, insights, critical reflections, and future outlook are also presented.

Metal–Organic Frameworks for Biomedical Applications

“…Imaging agents, such as fluorescent small molecules and imaging contrast agents, are employed to generate signals or enhance the signal contrast in targeted tissues. In the past several years, owing to the facile functionalization, diversiform structures and compositions, and large porosities of MOFs, MOF‐based nanocomposites are widely used in fluorescence imaging (FL), computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET) imaging 42. In this section, we will highlight the applications and potential advantages of MOF‐based nanocomposites as imaging contrast agents or imaging contrast carriers in monomodal and multimodal bioimaging applications.…”

“…MRI contrast agents can transform the longitudinal (T 1 ) and lateral (T 2 ) relaxation rates of water protons for disease diagnosis. To date, numerous MOFs that contain Gd, Mn, Fe, iron oxide, and their derivatives have been used in the development of MRI contrast agents to achieve high‐resolution MRI effects 42a,b,46. For example, Steunou and co‐workers designed a superparamagnetic mesoporous MIL‐100(Fe) composite decorated by maghemite (γ‐Fe 2 O 3 ) NPs for MRI imaging and cancer treatment 47.…”

“…Integrated multimodal diagnostic technologies in one system are long‐term challenges in the diagnosis of disease. Significantly, multimodal bioimaging, superimposed by two or more monomodal bioimaging, can comprehensively reflect the pathological information, and has been rapidly developed as a glorious technique of clinical diagnosis and disease detection 42c…”

The Chemistry of Reticular Framework Nanoparticles: MOF, ZIF, and COF Materials

“…Guest molecules can turn nanoparticles into probes for tracking applications in live cell imaging as well as theranostics applications when combined with drug delivery systems 21e,f,253,291. Different types of reticular nanoparticles have been developed for clinical diagnostics including computed tomography (CT)292 and magnetic resonance imaging (MRI) 20a,293,296. Magnetic response of active moieties or molecules can be incorporated into a porous framework, either as metal center, building block20a,294 or guest‐molecule occupying the host's pores 295.…”

CoFe2O4/TMU‐17‐NH2 as a hybrid magnetic nanocomposite catalyst for multicomponent synthesis of dihydropyrimidines

“…Over the past three decades, the synthesis of metal–organic frameworks (MOFs) as porous crystalline hybrid materials by assembling metal nodes and organic ligands has attracted considerable attention with the aim of finding meaningful applications in various fields such as gas storage and separation, drug delivery, optics, sensing and biomedical imaging . Due to the diversity in metal centres and functional groups, high surface area and tunable porosity, MOFs can be valid as versatile heterogeneous catalysts .…”