Extremely Stable Supramolecular Hydrogels Assembled from Nonionic Peptide Amphiphiles

Peptide hydrogels with high stability in different media are of great interest in biomedical applications. In this paper, we report an easy, fast, and scalable method for preparing a family of nonionic peptide amphiphiles (PAs) obtained by direct aminolysis of alkyl-oilgo­(γ-benzyl-l-glutamate) samples, which were synthesized via the alkyl amine-initiated sequence ring-opening reaction of α-amino acid <i>N</i>-carboxyanhydrides. One great advantage of this method is that vast chemical diversity and large-scale yields can be achieved easily using commercially available hydramines. These PA samples can readily form a clear hydrogel without any external aid and show exceptionally enhanced gelation properties with a critical gelation concentration as low as 0.05 wt %. The hydrogels are highly stable against extreme pH values of 1 and 14 and a high salt concentration of 200 mM NaCl. These properties combined with the shear-thinning properties make these PA hydrogels ideal candidates for the new generation of injectable scaffolds

Nanoasperity: Structure Origin of Nacre-Inspired Nanocomposites

Natural nacre with superior mechanical property is generally attributed to the layered “brick-and-mortar” nanostructure. However, the role of nanograins on the hard aragonite platelets, which is so-called nanoasperity, is rarely addressed. Herein, we prepared silica platelets with aragonite-like nanoasperities via biomineralization strategy and investigated the effects of nanoasperity on the mechanical properties of resulting layered nanocomposites composed of roughened silica platelets and poly(vinyl alcohol). The tensile deformation behavior of the nanocomposites demonstrates that nanograins on silica platelets are responsive for strain hardening, improved strength, and toughness. The structure origin is attributed to the nanoasperity-controlled platelet sliding