Abstract

Background: Metal-organic frameworks (MOFs), as attractive hybrid crystalline porous materials, are being increasingly investigated in biomedical applications owing to their exceptional properties, including high porosity, ultrahigh surface areas, tailorable composition and structure, and tunability and surface functionality. Of interest, in this review, is the design and development of MOF-based drug delivery systems (DDSs) that have excellent biocompatibility, good stability under physiological conditions, high drug loading capacity, and controlled/targeted drug release.

Objective: This review highlights the latest advances in MOFs as anticancer drug delivery systems (DDSs) along with insights on their design, fabrication, and performance under different stimuli that are either internal or external. The synthesis methods of MOFs, along with their advantages and disadvantages, are briefly discussed. The emergence of multifunctional MOF-based theranostic platforms is also discussed. Finally, the future challenges facing the developments of MOFs in the field of drug delivery are discussed.

Methods: The review was prepared by carrying out a comprehensive literature survey using relevant work published in various scientific databases.

Results: Novel MOFs in biomedical applications, especially in drug delivery, have shown great potential. MOF-based DDSs can be classified into normal (non-controllable) DDSs, stimuli-responsive DDSs, and theranostic platforms. The normal DDSs are pristine MOFs loaded with therapeutic agents and offer little to no control over drug release. Stimuli-responsive DDSs offer better spatiotemporal control over drug release by responding to either endogenous (pH, redox, ions, ATP) or exogenous stimuli (light, magnetism, US, pressure, temperature). The theranostic platforms combine stimuli-responsive drug delivery with diagnostic imaging functionality, paving the road for imaging-guided drug delivery.

Conclusion: This review presented a summary of the various methods utilized in MOF's synthesis along with the advantages and disadvantages of each method. Furthermore, the review highlighted and discussed the latest developments in the field of MOF-based DDSs and theranostic platforms. The review is focused on the characteristics of MOF-based DDSs, the encapsulation of different anticancer drugs as well as their stimuli-responsive release.

Keywords: Metal-organic frameworks, stimuli-responsive, drug delivery system, drug loading, drug release, cancer.

Graphical Abstract