Zeolitic imidazolate frameworks for use in electrochemical and optical chemical sensing and biosensing: a review

This review (with 145 refs.) summarizes the progress that has been made in the use of zeolitic imidazolate frameworks in chemical sensing and biosensing. Zeolitic imidazolate frameworks (ZIFs) are a type of porous material with zeolite topological structure that combine the advantages of zeolite and traditional metal-organic frameworks. Owing to the structural flexibility of ZIFs, their pore sizes and surface functionalization can be reasonably designed. Following an introduction into the field of metal-organic frameworks and the zeolitic imidazolate framework (ZIF) subclass, a first large section covers the various kinds and properties of ZIFs. The next large section covers electrochemical sensors and assays (with subsections on methods for gases, electrochemiluminescence, electrochemical biomolecules). This is followed by main sections on ZIF-based colorimetric and luminescent sensors, with subsections on sensors for metal ions and anions, for gases, and for organic biomolecules. The last section covers SERS-based assays. Several tables are presented that give an overview on the wealth of methods and materials. A concluding section summarizes the current status, addresses current challenges, and gives an outlook on potential future trends. In recent years, ZIFs and their composites have been widely used as probes in chemical sensing, and these probes have shown great advantages over other materials. This review describes the current progress on ZIFs toward electrochemical, luminescence, colorimetric, and SERS-based sensing applications, highlighting the different strategies for designing ZIFs and their composites and potential challenges in this field.