“Dynamic” molecular recognition and chirality segregation utilizing concepts of molecular machines and molecular assemblies

Abstract

The need to measure the concentration of selected ions and small organic molecules in both in vivo and in vitro processes is continuously increasing beyond the borders of various research fields. This need has been fulfilled using “host–guest chemistry”, or in general, by the use of “molecular recognition”. The basic idea in these research fields was derived from the 1 : 1 host–guest interaction based on the “key-and-lock” concept. However, we have experienced that only with this classical concept, more precise, higher-order recognition faces serious difficulty. In this review article, I wish to explain that the introduction of two new concepts, i.e., the dynamic action of molecular systems and the amplification effect of molecular assemblies, overcame the limitation of the “key-and-lock” concept. In fact, we have found that even “complete” chirality segregation can be achieved under optimal conditions.

The Past and the Future of Langmuir and Langmuir–Blodgett Films

“…The switching mode is the second generation of molecular recognition where recognition efficiency can be changed by switching receptor structures as seen in photoisomerization of receptors. 556,557 This mode requires switching of receptor−guest complex structures by external stimuli, which is the basis of most molecular machines. 558−560 Unlike these previous modes, molecular tuning at the air−water interface is based on continuous changes of receptor conformation.…”

“…The first generation of molecular recognition is based on the stable structure of a receptor–guest complex, − with a univocal guest recognition by a host molecule as typical systems such as crown ethers and cyclodextrins. The switching mode is the second generation of molecular recognition where recognition efficiency can be changed by switching receptor structures as seen in photoisomerization of receptors. , This mode requires switching of receptor–guest complex structures by external stimuli, which is the basis of most molecular machines. − Unlike these previous modes, molecular tuning at the air–water interface is based on continuous changes of receptor conformation. This is an optimization from the numerous candidates of receptor structures and may be regarded as the third generation of molecular recognition.…”

“…The LB technique can be used to control life (living cells) since tailored nanostructures can regulate cell behavior. − Since the vortex LB method may be used to align nanoscopic and microscopic objects, it was employed to produce aligned arrays of fullerene whiskers with different curvatures from a one-dimensional C 60 assembly. Cultures of the human osteoblast cell line MG63 were bound preferentially to the fullerene whiskers, probably due to the adsorption of the extracellular matrix, thus leading to cell growth along with the array of fullerene whiskers. − Aligned and controlled one-dimensional C 60 nanowhiskers were functional scaffolds for long-term maintenance of self-renewal and multipotency of human mesenchymal stem cells, as illustrated in Figure . Human mesenchymal stem-cell-based therapies are promising for tissue regeneration owing to their multipotency, accessibility, and immunosuppressive properties, but the limited supply from human sources could hinder practical clinical applications.…”

Molecular Machines and Microrobots: Nanoarchitectonics Developments and On-Water Performances

“…Molecular recognition began with the primary recognition of guests by host molecules such as crown ethers and cyclodextrins [ 176 , 177 , 178 ]. A mode of switching selectivity (transitioning between multiple stable states) was incorporated by isomerization of the host [ 179 , 180 ]. In fact, most of the current molecular machines are based on this switching of stable states and have not departed from this stage [ 181 , 182 ].…”

The evolution of molecular machines through interfacial nanoarchitectonics: from toys to tools

“…10B). 76,77 This switching mechanism utilizes two or more stable states to control recognition capability by external stimuli. Unlike these two traditional mechanisms, receptor tuning at a dynamic interface is based on selection and optimization from numerous conformational candidates of receptors (Fig.…”