Recent progress in biological and chemical sensing by luminescent metal-organic frameworks

Abstract

Luminescent metal organic frameworks (LMOFs), formed by coordinated bridging between metal ions and multidentate organic ligands with relevant fluorescent structures, have been the subject of intense research due to their tunable photoluminescent properties. The numerous permutations and combinations of available metal ions and organic linkers can yield novel LMOFs for countless applications. The luminescent characteristics of LMOFs depend upon many factors, including their structural components, coordination milieu of the metal ions, chemical structure/volume of the pore surfaces, and host-guest interactions between the LMOFs and reacting species (e.g., non-covalent interactions, coordination bonds, and π-π interactions). The combined effects of these parameters justify the expansion of their application in various fields. In addition, they are recognized as ideal candidates for biological applications due to their high loading capacity of functional molecules, facile surface modification and conjugation with biocompatible ligands (such as antibodies and proteins), tunable structural geometry, and intrinsic biocompatibility. By elaborating on these points, this article provides up-to-date information on the developments in the scientific/technological application of LMOFs, with special emphasis on the types, properties, and potential in sensing and biological applications. The discussion is further expanded to describe the major challenges and constraints of this research field.