Design of chemical valve system based on the concept of molecular-specific synchronization

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The objective of this study is to construct chemical-valve system based on the concept of molecular synchronization. For this purpose, two-types of materials systems were examined here : (1)Networked structure of polymers (polymeric gels) and (2)nano-associates of block copolymers (polymeric micelles). The former system was focused on the development of materials undergoing abrupt change in their volume at physiological condition responding to external glucose concentration. A basis of the system studied here is the shift in the equilibrium between the uncharged and charged form of phenylboronic acid moieties in the polymer chain thorough complex formation with glucose. An increased glucose-concentration shifts the equilibrium in the direction of increasing fraction of borate anions and decreasing the fraction of the uncharged form. Charged borates are certainly more hydrophilic than the uncharged form. Thus, a glucose-dependent change in the ratio between uncharged and charged borates in the polymer chain should crucially affect the polymer solubility, if the polymer chain has an amphiphilic character. Apparently, this materials system should be useful to construct self-regulating insulin-releasing device for the treatment of diabetes. The latter system was designed to dissociate upon its internalization into the intracellular compartment so as to release cargo compounds selectively inside of target cells. These stimuli-sensitive polymeric micelles should be useful as nanocanrriers for gene and drug delivery.