Expanding the useful lifespan of materials is becoming highly desirable, and self-healing and self-repairing materials may become valuable commodities. The formation of supramolecular materials through host–guest interactions is a powerful method to create non-conventional materials. Here we report the formation of supramolecular hydrogels and their redox-responsive and self-healing properties due to host–guest interactions. We employ cyclodextrin (CD) as a host molecule because it is environmentally benign and has diverse applications. A transparent supramolecular hydrogel quickly forms upon mixing poly(acrylic acid) (pAA) possessing β-CD as a host polymer with pAA possessing ferrocene as a guest polymer. Redox stimuli induce a sol−gel phase transition in the supramolecular hydrogel and can control self-healing properties such as re-adhesion between cut surfaces.

Metazoans express three unfolded protein response transducers (IRE1, PERK, and ATF6) ubiquitously to cope with endoplasmic reticulum (ER) stress. ATF6 is an ER membrane-bound transcription factor activated by ER stress-induced proteolysis and has been duplicated in mammals. Here, we generated ATF6alpha- and ATF6beta-knockout mice, which developed normally, and then found that their double knockout caused embryonic lethality. Analysis of mouse embryonic fibroblasts (MEFs) deficient in ATF6alpha or ATF6beta revealed that ATF6alpha is solely responsible for transcriptional induction of ER chaperones and that ATF6alpha heterodimerizes with XBP1 for the induction of ER-associated degradation components. ATF6alpha(-/-) MEFs are sensitive to ER stress. Unaltered responses observed in ATF6beta(-/-) MEFs indicate that ATF6beta is not a negative regulator of ATF6alpha. These results demonstrate that ATF6alpha functions as a critical regulator of ER quality control proteins in mammalian cells, in marked contrast to worm and fly cells in which IRE1 is responsible.

Microtubule-dependent motor, murine KIF3B, was disrupted by gene targeting. The null mutants did not survive beyond midgestation, exhibiting growth retardation, pericardial sac ballooning, and neural tube disorganization. Prominently, the left-right asymmetry was randomized in the heart loop and the direction of embryonic turning. lefty-2 expression was either bilateral or absent. Furthermore, the node lacked monocilia while the basal bodies were present. Immunocytochemistry revealed KIF3B localization in wild-type nodal cilia. Video microscopy showed that these cilia were motile and generated a leftward flow. These data suggest that KIF3B is essential for the left-right determination through intraciliary transportation of materials for ciliogenesis of motile primary cilia that could produce a gradient of putative morphogen along the left-right axis in the node.

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Cyclodextrins have been used as a cyclic component in the construction of supramolecular architectures. Recently they have been studied as a component in the construction of rotaxanes and catenanes. A cyclodextrin ring can translocate in some rotaxane and catenane structures. Therefore, much attention has been given to cyclodextrins as a component of molecular shuttles, motors, and machines. Attempts to design and synthesize molecular-level machines using cyclodextrins as a cyclic component are described.