Metal-organic frameworks for stimuli-responsive drug delivery.

Metal-organic framework (MOF), a novel hybrid porous material which is composited by metal ions and organic linkers, has drawn increasing attention and became a promising material in the biomedical field owing to their unique properties including large pore volume, high surface area, tunable pore size, versatile functionality and high drug loading efficiency. However, the MOF families and members, and the drug release mechanisms in MOF-based stimuli-responsive drug delivery systems (DDSs) are rarely summarized. Here, we systematically classified the families of MOF and introduced some representative members in MOF families. Moreover, the underlying drug release mechanisms were interpreted according to endogenous stimuli (include pH, glutathione (GSH), adenosine-triphosphate (ATP), ion, glucose, enzyme, HS, and etc.) and the exogenous stimuli (include light, temperature, pressure, and etc.). Furthermore, the remaining challenges and future directions of DDSs based on MOF are discussed and proposed. This review revealed the relationship between the structure and properties of MOF. A better understanding of these release mechanisms under different stimuli would benefit the designing of sophisticated DDSs based on the promising material of MOF.