Recent Advances in Metal-Organic Frameworks as Anticancer Drug Delivery Systems: A Review.

BACKGROUND Metal-organic frameworks (MOFs), as attractive hybrid crystalline porous materials, are increasingly being 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 MOFbased 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 potentials. 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 MOFs and offer little to no control over the drug delivery. Stimuli-responsive DDSs offer better spatiotemporal control over the 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 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.