Chemical Stability of Metal‐organic Frameworks for Applications in Drug Delivery

Abstract

Structural variety, tunable porosity and opportunities for functionalization make metal‐organic frameworks (MOFs) promising materials for applications in medicine as drug delivery systems. In this minireview, an overview of chemical stability of MOF nanocarriers at simulated body conditions is presented. Parameters such as a choice of buffer, pH value, nanoparticle size or surface modification are discussed, as well as analytical methods and approaches suitable to determine the material stability. Last but not least, examples of tuning and improving the chemical stability of MOF nanoparticles for solution‐based drug delivery (oral and intravenous) are presented and examples of MOFs as pH‐responsive drug nanocarriers are given.

Perspectives on the Influence of Crystal Size and Morphology on the Properties of Porous Framework Materials

“…They reported that PCN-224 with a particle size of 90 nm loaded with a photosensitizer were better performing in photodynamic therapy than PCN-224 with a particle size of 190 nm. Moreover, since MOFs are considered to be intrinsically biodegradable, the particle size influences also the overall carrier stability ( Bunzen, 2021 ). For instance, Falcaro et al reported on the chemical stability of ZIF-8 with regard to the particle size ( Velásquez-Hernández et al, 2019 ).…”

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

“…128−130 Wang et al reported on a pH-responsive fluorinated ZIF for in vitro and in vivo 19 F MRI. 128 ZIF-8 comprises Zn(II) ions and 2-methylimidazolate ligands and is known to be pHresponsive (stable at neutral and slightly basic conditions, but rather unstable in acidic conditions 131,132 ). In this work, some of the ligands were exchanged to 4-(trifluoromethyl)imidazole to provide the fluorine moieties for the detection by 19 F MRI.…”

Biofunctionalized metal–organic frameworks and host–guest interactions for advanced biomedical applications

“…64,65 As discussed by McKinlay et al, one of the biggest potential drawbacks for MOFs is their chemical stability, which happens to depend on several factors such as the operating environment, temperature, pH conditions, and particle size. 66,67 The enhanced chemical instability of MOFs could actually be a desirable characteristic, as it would prevent an endogeneous accumulation of potentially toxic ions and MOF precursors in the living system. 64 Control over the physical and chemical properties of MOFs via biofunctionalization could ensure a stability of up to several days, or even weeks, which would be enough to ensure completion of its intended function, such as drug delivery, bio-sensing or bio-imaging.…”