Dilution-induced gel-sol-gel-sol transitions by competitive supramolecular pathways in water

Abstract

Fascinating properties are displayed by synthetic multicomponent supramolecular systems that comprise a manifold of competitive interactions, thereby mimicking natural processes. We present the integration of two reentrant phase transitions based on an unexpected dilution-induced assembly process using supramolecular polymers and surfactants. The co-assembly of the water-soluble benzene-1,3,5-tricarboxamide (BTA-EG 4 ) and a surfactant at a specific ratio yielded small-sized aggregates. These interactions were modeled using the competition between self-sorting and co-assembly of both components. The small-sized aggregates were transformed into supramolecular polymer networks by a twofold dilution in water without changing their ratio. Kinetic experiments show the in situ growth of micrometer-long fibers in the dilution process. We were able to create systems that undergo fully reversible hydrogel-solution-hydrogel-solution transitions upon dilution by introducing another orthogonal interaction.

Hybrid Hydrogels from Nongelling Polymers Using a Fibrous Peptide Hydrogelator at Low Concentrations

“…Low-molecular-weight (LMW) gelators represent a promising class of soft materials in a wide range of applications. − The LMW gels are mainly constructed through noncovalent interactions including hydrogen bonding, hydrophobic, π–π stacking, van der Waals, and electrostatic interactions. − They have significant advantages owing to facile synthesis, diverse structures, tunable properties, and rapid response to external stimuli. ,− Particularly, peptide-based hydrogelators are intriguing biomaterials due to their excellent biocompatibility, low immunogenicity, and adaptable secondary conformations, which enable excellent candidates for drug delivery, tissue engineering, and wound healing. − The peptide hydrogelators generally form a fibrillar network structure through molecular self-assembly. ,− Numerous peptide hydrogelators have been constructed from oligopeptides, , Fmoc peptides, − peptide amphiphiles (PAs), − and cyclic dipeptides . However, merely a few LMW peptide hydrogelators have been reported to trigger the gelation of polymers, and the gelation concentration is generally high. − …”

Density-tunable pathway complexity in a minimalistic self-assembly model

“…By contrast, using monomer concentration to select different products among self-limited assemblies has proved much more elusive, and only a few specific examples have been reported, showing the potential of the approach. 54…”

“…By contrast, using monomer concentration to select different products among self-limited assemblies has proved much more elusive, and only a few specific examples have been reported, showing the potential of the approach. 54 The inherent challenges for such use of monomer concentration are aptly illustrated by processes resulting in onedimensional, polymer-like assemblies, such as tubules, 55 cylindrical micelles 56 and supramolecular polymers. 14,54 The string-like species formed in equilibrium are poly-dispersed in length, their abundance decaying exponentially with the polymerization degree.…”

“…54 The inherent challenges for such use of monomer concentration are aptly illustrated by processes resulting in onedimensional, polymer-like assemblies, such as tubules, 55 cylindrical micelles 56 and supramolecular polymers. 14,54 The string-like species formed in equilibrium are poly-dispersed in length, their abundance decaying exponentially with the polymerization degree. Varying monomer density can change the exponential decay length, skewing the population towards shorter or longer species, but no tuning of the density can e.g.…”

A structural platform for B cell receptor signaling

“…The cryo-EM structures of human IgM-BCR and IgG-BCR reported by the Zhiwei Huang lab, 6 together with that of human IgM-BCR by the Yigong Shi lab 7 and murine IgM-BCR by the Hao Wu lab 8 define the organization principles of BCR assembly. Notably, the Yigong Shi lab used IgM-BCR bound to Polatuzumab vedotin Fab fragment, an Igβ-targeting monoclonal antibody conjugated to an antimitotic agent that has been approved for the treatment of B-cell lymphomas.…”