Cyclodextrins (CDs) are a class of cyclic oligosaccharides consisting of several α-(1,4)-linked d-glucose units. They have a cavity of sub-nanometer size, into which a guest molecule of the appropriate size and shape can be selectively incorporated. The ability of CDs to form inclusion complexes with guest molecules has been widely used both academically and industrially. However, most of inclusion complex formation with CDs has been limited to aqueous media. Recently, the authors succeeded in developing CD derivatives that can effectively include guest molecules in oils and nonpolar organic solvents. This review describes molecular recognition in organic solvents by new CD dimers with different linkers and substituent groups, which were designed and synthesized based on the knowledge obtained so far.

Natural cyclodextrins (CDs) and their derivatives are host molecules that form inclusion complexes with hydrophobic drugs and are widely applied as pharmaceutical additives and DDS carriers in the pharmaceutical field. Recently, supramolecular necklaces using CDs have also been attracting attention, and their functions have been found to be superior to those of conventional low-molecular-weight or high-molecular-weight drug formulation materials. In addition, a paradigm shift is taking place in which CDs themselves are being used as active pharmaceutical ingredients. This paper reviews the creation of CD-based materials and their application to pharmaceuticals.

Because of their simplicity and low cost, analytical reagents (i.e., chemosensors,) have been actively developed toward future applications for healthcare and biological studies. However, conventional molecular probes, the basic structures of analytical reagent, are typically insoluble in water, and their synthesis often requires complicated protocols. To address these issues, cyclodextrins (CyDs) are a promising clue owing to the encapsulation ability that solubilizes various organic compounds in water and can supramolecularly add molecular recognition moieties. We have conceptualized the design of cyclodextrin-based supramolecular analytical reagents, in which hydrophobic molecular probes are encapsulated in the CyD cavity that offers a nano-sized hydrophobic reaction field in water. In this review, we have summarized the basic concepts of analytical reagent and pointed out facing issues in this research area. Then, we have introduced successful examples of CyD-based supramolecular analytical reagents showing fluorescent, colorimetric, and electrochemical signals, mainly from our recent publications. We believe that the concept of CyD-based supramolecular analytical reagents will innovate the design of chemosensing system by providing unconventional molecular selectivity that cannot be achieved with traditional molecular probes.

Do you know the field of biomimetic chemistry? This is an interdisciplinary research field in chemistry that focuses on producing the functions of natural biomolecules using chemically synthesized compounds. Our group has developed artificial hemoglobin compounds using cyclodextrin derivatives for many years. Our original biomimetic model complex, hemoCD, is the only example as artificial hemoglobin compounds that function in water as well as in vivo. HemoCD can transport oxygen like hemoglobin, while hemoCD strongly binds CO and excreting CO in the urine. Therefore, hemoCD shows high potential as an emergency drug for fire-gas poisoning. In this paper, we introduce our drug development research based on biomimetic chemistry.