Biomimetic Strain-Stiffening Self-Assembled Hydrogels

Supramolecular structures with strain-stiffening properties are ubiquitous in nature but remain rare in the lab. Herein, we report on strain-stiffening supramolecular hydrogels that are entirely produced through the self-assembly of synthetic molecular gelators. The involved gelators self-assemble into semi-flexible fibers, which thereby crosslink into hydrogels. Interestingly, these hydrogels are capable of stiffening in response to applied stress, resembling biological intermediate filaments system. Furthermore, strain-stiffening hydrogel networks embedded with liposomes are constructed through orthogonal self-assembly of gelators and phospholipids, mimicking biological tissues in both architecture and mechanical properties. This work furthers the development of biomimetic soft materials with mechanical responsiveness and presents potentially enticing applications in diverse fields, such as tissue engineering, artificial life, and strain sensors.     

Precise Size-Selective Sieving of Nanoparticles Using a Highly Oriented Two-Dimensional Supramolecular Polymer

The development of size-selective membranes with well-defined nanopores towards the precise separation of nanometer-sized substances is a challenging task to achieve. Here a supramolecular membrane is presented that comprises a highly oriented, honeycomb-like, 2D supramolecular polymer on a polycarbonate filter support. It enables precise size-selective sieving of colloidal nanoparticles (NPs). Owing to the uniform parallel-aligned nanocavities within the 2D supramolecular polymers, the composite membrane shows a high size-selectivity with a sub-nanometer accuracy in the cutoff size of about 4.0 nm. In principle, the species of size-separable particles are unlimited, as demonstrated by quantum dots, noble metal, and metal oxide NPs. This supramolecular membrane combined with filtration advances the potential of NPs in terms of their monochromatic emission and size monodispersity, and also enables rapid removal of small magnetic NP adsorbents that are otherwise difficult to capture.