Preparation of Gadolinium‐Based Metal‐Organic Frameworks and the Modification with Boron‐10 Isotope: A Potential Dual Agent for MRI and Neutron Capture Therapy Applications

One-pot hydrothermal synthesize and characterization of Au/Gd bimetallic nanostructure as potential contrast agents in CT and MR imaging

Introduction

Multimodal contrast agents play an important role in early diagnosis of diseases and monitoring the treatment outcomes by increasing the accuracy and clarity of images.

Methods

Herein, a one-step simple hydrothermal route is utilized to prepare the gadolinium-1,4 H2BDC- metal-organic framework (Gd-BDC-MOF) nanoparticles decorated with gold nanoclusters. The physicochemical properties of bimetal nanostructures were evaluated, their safety and ability to enhance contrast in both CT and MR imaging were also examined.

Results

The spherical nano-sized Au decorated Gd bimetal nanostructures have an average diameter of 64 nm. The presence of both Au and Gd metals in the prepared nanostructure was confirmed using EDAX. The XRD pattern shows that, in the hydrothermal synthesis of two metals using a terephthalic acid linker, gold nanoclusters are decorated onto the gadolinium metal organic framework. The FTIR analysis confirmed the attachment of Gd to the carboxylate group of the organic linker. The bimetal nanostructure sample with a concentration of 40 mM showed similar X-ray attenuation to that of iodine at a concentration of 128 mM. At a magnetic field strength of 1.5 T, the longitudinal relaxivity value of the bimetal nanostructure was determined to be 13.635 mM-1 s-1. The MTT assay demonstrated the cytocompatibility and safety of the contrast agent synthesized for biomedical applications.

Conclusion

The fabricated bimetal nanostructure exhibits dose-dependent positive contrast enhancement in both MR and CT imaging techniques, making it a promising candidate for use as a contrast agent in medical applications.

Metal-organic frameworks: A promising option for the diagnosis and treatment of Alzheimer's disease

Beta-amyloid (Aβ) peptide is one of the main characteristic biomarkers of Alzheimer's disease (AD). Previous clinical investigations have proposed that unusual concentrations of this biomarker in cerebrospinal fluid, blood, and brain tissue are closely associated with the AD progression. Therefore, the critical point of early diagnosis, prevention, and treatment of AD is to monitor the levels of Aβ. In view of the potential of metal-organic frameworks (MOFs) for diagnosing and treating the AD, much attention has been focused in recent years. This review discusses the latest advances in the applications of MOFs for the early diagnosis of AD via fluorescence and electrochemiluminescence (ECL) detection of AD biomarkers, fluorescence detection of the main metal ions in the brain (Zn2+, Cu2+, Mn2+, Fe3+, and Al3+) in addition to magnetic resonance imaging (MRI) of the Aβ plaques. The current challenges and future strategies for translating the in vitro applications of MOFs into in vivo diagnosis of the AD are discussed.

Recent Advances in Metal-Organic Frameworks for Applications in Magnetic Resonance Imaging

Diagnostics is an important part of medical practice. The information required for diagnosis is typically collected by performing diagnostic tests, some of which include imaging. Magnetic resonance imaging (MRI) is one of the most widely used and effective imaging techniques. To improve the sensitivity and specificity of MRI, contrast agents are used. In this review, the usage of metal-organic frameworks (MOFs) and composite materials based on them as contrast agents for MRI is discussed. MOFs are crystalline porous coordination polymers. Due to their huge design variety and high density of metal ions, they have been studied as a highly promising class of materials for developing MRI contrast agents. This review highlights the most important studies and focuses on the progress of the field over the last five years. The materials are classified based on their design and structural properties into three groups: MRI-active MOFs, composite materials based on MOFs, and MRI-active compounds loaded in MOFs. Moreover, an overview of MOF-based materials for heteronuclear MRI including 129Xe and 19F MRI is given.

Adsorption Behavior of a Gd-Based Metal-Organic Framework toward the Quercetin Drug: Effect of the Activation Condition

A carboxylate gadolinium-based metal-organic framework (Gd-MOF) is an exceptional candidate for magnetic resonance imaging agents, but its low drug adsorption capacity hinders this MOF from being used as a theragnostic agent. In this work, the Gd-MOF was synthesized by a simple solvothermal method. Then, different activation situations, including various solvents over different time periods, were applied to enhance the specific surface area of the synthesized MOF. Different characterization analyses such as X-ray diffraction and Brunauer-Emmett-Teller along with experimental quercetin adsorption tests were done to study the crystalline and physical properties of various activated MOFs. In the following, the MOF activated by ethanol for 3 days (3d-E) was chosen as the best activated MOF due to its crystallinity, highest specific surface area, and drug adsorption capacity. More explorations were done for the selected MOF, including the drug adsorption isotherm, thermodynamics, and pH effect of adsorption. The results show that the activation process substantially affects the crystallinity, morphology, specific surface area, and drug adsorption capacity of Gd-MOFs. An optimized activation condition is proposed in this work, which shows an impressive enhancement of the specific surface area of Gd-MOFs just by simple solvent exchange method employment.