Synthetic diblock copolypeptides were designed to incorporate oppositely charged ionic segments that form β-sheet-structured hydrogel assemblies via polyion complexation when mixed in aqueous media. The observed chain conformation directed assembly was found to be required for efficient hydrogel formation and provided distinct and useful properties to these hydrogels, including self-healing after deformation, microporous architecture, and stability against dilution in aqueous media. While many promising self-assembled materials have been prepared using disordered or liquid coacervate polyion complex (PIC) assemblies, the use of ordered chain conformations in PIC assemblies to direct formation of new supramolecular morphologies is unprecedented. The promising attributes and unique features of the β-sheet-structured PIC hydrogels described here highlight the potential of harnessing conformational order derived from PIC assembly to create new supramolecular materials.
Diblock, triblock and pentablock copolypeptides were designed and prepared for formation of polyion complex hydrogels in aqueous media. Increasing the number of block segments was found to allow formation of hydrogels with substantially enhanced stiffness at equivalent concentrations. Use of similar length ionic segments also allowed mixing of different block architectures to fine tune hydrogel properties. The pentablock hydrogels possess a promising combination of high stiffness, rapid self-healing properties, and cell compatible surface chemistry that makes them promising candidates for applications requiring injectable or printable hydrogel scaffolds. Polyion complex (PIC) assembly of dual hydrophilic block copolymers containing non-ionic and oppositely charged ionic segments has been developed as a facile method to prepare a diverse array of micelles, vesicles, and hydrogels in aqueous media. 1-3 Due to the high water solubility of precursors, PIC formation allows the preparation of supramolecular assemblies at high concentrations via simple mixing, and does not require the use of either heating or cosolvents. These assemblies are experiencing extensive development in applications, including as carriers for therapeutic molecules and as scaffolds for cell culture and tissue repair. 1-5 We recently reported the design of PIC diblock copolypeptide hydrogels
We developed quantum dot-engineered M13 virus layer-by-layer hybrid composite films with incorporated fluorescence quenchers. TNT is designed to displace the quenchers and turn on the quantum dot fluorescence. TNT was detected at the sub ppb level with a high selectivity.
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