Photo Gel–Sol/Sol–Gel Transition and Its Patterning of a Supramolecular Hydrogel as Stimuli‐Responsive Biomaterials

Abstract

In a focused library of glycolipid-based hydrogelators bearing fumaric amide as a trans-cis photoswitching module, several new photoresponsive supramolecular hydrogelators were discovered, the gel-sol/sol-gel transition of which was pseudo-reversibly induced by light. Studying the optimal hydrogel by NMR spectroscopy and various microscopy techniques showed that the trans-cis photoisomerization of the double bond of the fumaric amide unit effectively caused assembly or disassembly of the self-assembled supramolecular fibers to yield the macroscopic hydrogel or the corresponding sol, respectively. The entanglement of the supramolecular fibers produced nanomeshes, the void space of which was roughly evaluated to be 250 nm based on confocal laser scanning microscopy observations of the size-dependent Brownian motion of nanobeads embedded in the supramolecular hydrogel. It was clearly shown that such nanomeshes become a physical obstacle that captures submicro- to micrometer-sized substrates such as beads or bacteria. By exploiting the photoresponsive property of the supramolecular nanomeshes, we succeeded in off/on switching of bacterial movement and rotary motion of bead-tethered F(1)-ATPase, a biomolecular motor protein, in the supramolecular hydrogel. Furthermore, by using the photolithographic technique, gel-sol photopatterning was successfully conducted to produce sol spots within the gel matrix. The fabricated gel-sol pattern not only allowed regulation of bacterial motility in a limited area, but also off/on switching of F1-ATPase rotary motion at the single-molecule level. These results demonstrated that the photoresponsive supramolecular hydrogel and the resulting nanomeshes may provide unique biomaterials for the spatiotemporal manipulation of various biomolecules and live bacteria.

Hierarchical supramolecular hydrogels: self-assembly by peptides and photo-controlled release via host–guest interaction

“…Photo-switchable moieties are notably fascinating because they support the establishment of light-responsive peptide hydrogels. LMWGs comprising azobenzenes [35][36][37] and stilbenes 26,38,39 are two important variations of this approach. Azobenzene is unique since it can be readily photo-isomerized as well as form photo-responsive inclusion complex with b-CD via host-guest interaction in water.…”

Structural hydrogels

“…For example, Huang et al [201] reported the method to fabricate hierarchical one-dimensional (1D) hydrogels architectures including nanotubes, coiled-coil ropelike structures, nanohelices, and nanoribbons via lanthanum-cholate supramolecular self-assembly, mediated by temperature. Besides, hydrogel patterns at micron scale or macro scale can also be obtained via supramolecular self-assembly [202][203][204]. These structured supramolecular hydrogels were anticipated to generate versatile applications in cell culture, tissue engineering, biomedical science and biosensor.…”

Stimuli‐Responsive Systems

“…In the course of the research of Hamachi and coworkers on organo-and hydrogelators based on glycosylated amino acids, Matsumoto and coworkers [75] synthesized a variety of compounds based on fumaric acid diamide to obtain photo-responsive hydrogels (Scheme 11.22). Some of the compounds did form photo-responsive hydrogels: their solutions underwent a gel-to-sol transition upon E-to-Z photoisomerization and vice versa.…”