An unusual polyoxometalate-encapsulating 3D polyrotaxane framework formed by molecular squares threading on a twofold interpenetrated diamondoid skeleton.

Threading molecular square "beads" on a twofold interpenetrated diamondoid skeleton gives a new type of 3D metal-organic polyrotaxane framework with large channels, in which nanosized Keggin anions as guests are encapsulated for the first time.

Metal-organic frameworks as potential drug delivery systems.

INTRODUCTION: Metal-organic frameworks (MOFs) are a unique class of hybrid porous solids based on metals and organic linkers. Compared to traditional porous materials, they possess predominance of large surface areas, tunable pore size and shape, adjustable composition and functionalized pore surface, which enable them unique advantages and promises for applications in adsorption and release of therapeutic agents. AREAS COVERED: This review addresses MOFs as a new avenue for drug delivery and exhibits their ability to efficiently deliver various kinds of therapeutic agents. It also details the requirements that MOFs need to satisfy for biomedical application, such as toxicological compatibility, stability, particle size, and surface modification. In addition, several approaches used to enhance encapsulation efficiency are summarized and parameters influencing delivery efficiency are also discussed. EXPERT OPINION: Benefiting from the unique advantages of MOFs materials, efficient delivery of various kinds of drugs has been achieved in some MOF materials. However, it is only the outset of MOFs in drug delivery system, and numerous work need to be done before clinical applications, for example, studying their in vivo toxicity, exploring degradation mechanisms so as to establish real stability of MOFs in body's liquid, providing appropriated surface modification avenue for MOFs, and researching in vivo efficiency and pharmacokinetics of drug-loaded MOFs.