Temperature-Induced Nanostructure Transition for Supramolecular Gelation in Water

Abstract

Thermogel is an injectable biomaterial that functions at body temperatures due to the ease of the sol-togel transition. However, most conventional physically crosslinked thermogels generally have relatively low stiffness, which limits various biomedical applications, particularly for stem-cellbased studies. While chemical cross-linking through doublenetwork (DN) structures can increase the stiffness of the hydrogel, they generally lack injectable and thermoresponsive properties due to strong covalent bonds between molecules. To address this challenge, we have developed a temperatureinduced nanostructure transition (TINT) system for preparing physical DN supramolecular hydrogels. These hydrogels possess injectable, thermoreversible characteristics and relatively high storage modulus (G′), which increases ∼14-fold from 20 to 37 °C (body temperature). Our bottom-up strategy is based on the co-assembly of aromatic peptide (Ben-FF) and poly(ethylene glycol) (PEG) to form a thermogel at 37 °C through a nanofiber dissociation pathway that differs from the well-known micelle aggregation or polymer shrinkage mechanisms. Peptide molecules form helical packing and weak, noncovalent interactions with PEG, resulting in co-assembled metastable nanofibers. Thermal perturbation initiates lateral dissociation of nanofibers into extensively cross-linked DN nanostructures and subsequent hydrogelation (ΔG = −13.32 kJ/mol). The TINT hydrogel is nontoxic to human mesenchymal stem cells and supports enhanced cell adhesion, suggesting the potential of this strategy in the applications of tissue engineering and regenerative medicine.

Poly(l-threonine-co-l-threonine Succinate) Thermogels for Sustained Release of Lixisenatide

“…The HOD peak at 4.83 ppm shifted to 4.63 ppm, and the peak rather collapsed as the temperature increased from 20 to 50 °C (Figure c). Such changes are caused by changes in the polymer–water interactions and dehydration of the polymers at high temperatures. , In addition, the methyl peak of l -Thr at 1.228 ppm shifted to 1.223 ppm, whereas that of succinylated l -Thr remained at 1.275 ppm (Figure c dashed line in the inset). Although the change in chemical shift is small, the data suggest that dehydration of the l -Thr bearing a hydroxy group is more directly involved in the sol-to-gel transition.…”

Photofabrication of fluorescent nanospheres from de novo designed peptides, and their enzyme-responsive dissociation in living cells

“…[13][14][15][16] Peptide assemblies are ordinarily governed by a combination of noncovalent and covalent interactions, encompassing hydrogen bonds, 17 p-p stacking, 18 hydrophobic interactions, 19,20 coulombic forces, 21,22 disulfide S-S bonds, 23,24 L-phenylalanine polymerization, dityrosine crosslinking, [25][26][27] and so on, which could drive peptide self-assembly processes, stabilize secondary or tertiary structures, and establish conjugation patterns even at the protein level. Tremendous efforts have been made to exploit de novo designed peptides and mimic bioactive assemblies, however, the function-oriented synthesis is still limited by many influencing factors of pH environment, [28][29][30] working temperature, [31][32][33] ionic strength, 34,35 hydrophilic/hydrophobic properties, 36,37 pre-assembly method, 38,39 host-guest modeling, 40,41 spacer occupation, 42,43 and so on.…”

CO2-Responsive Rosin-Based Supramolecular Hydrogels: Diverse Chiral Nanostructures and Their Application in In Situ Synthesis of Chiral Gold Nanoparticles

“…Chirality is ubiquitous and essential in living organisms and can be formed at different scales, from the molecule to supramolecule and the nanoscale to macroscale. Chiral nanostructures prepared from supramolecular assemblies have attracted considerable attention due to their excellent properties in the fields of sensing, , recognition, , biological medicine, , and catalysis. , It has been proven that the chirality of nanostructures is usually determined by their molecular chirality. , In addition, the chirality of the nanostructures can be controlled by changing the molecular structure or the solvent. Rosin is an abundant biomass resource, and its main component is abietic acid.…”