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Herein, we report the synthesis of simple TPE/single amino acid conjugates, TPE-Ser and TPE-Asp with side-chains featuring functional groups that may provide an additional hydrogen bonding network for hydrogelation in aqueous medium. TPE-Ser, which has the lowest molecular weight, containing hydroxyl groups undergoes self-assembly into supramolecular hydrogels under physiological pH conditions. TPE-Asp with a carboxylic group side chain undergoes the self-assembly and hydrogelation processes under slightly acidic conditions (pH = 6.0). UV-vis, IR, PL and rheological studies clearly indicate the formation, stability and fluorescence properties of TPE-amino acid hydrogels. TEM micrographs of the hydrogels indicate that the compounds are self-assembled into a nanosheet morphology with random size and shape. Further, in vitro analysis of TPE-Ser and TPE-Asp with 3A6 cells shows that the compounds exhibit unique fluorescence signals in microcellular environments thus making them suitable candidates for bioimaging applications. Overall, these findings highlight the importance of the structure-hydrogelation relationship and provide new insights into the design of single amino-acid-based supramolecular hydrogels.

Herein, we report the synthesis and optimization of an aqueous phase two-component co-assembled nanofibrous hydrogel based on charge-transfer (CT) between pyrenebutyric acid and naphthalene diimide-capped groups. This donor–acceptor CT interaction is a powerful driving force that can induce self-assembly in the aqueous phase even if the molecule contains only a single amino acid. The intermolecular CT interactions for mixed components can also be visualized in the quantum-chemical approach. This two-component supramolecular co-assembly provides a new path for the design of self-assembled nanomaterials.

Gelatin is an important hydrocolloid which has widespread applications in the pharmaceutical industry and biomedical science. However, despite its significance, clinical applications of gelatin are largely limited because of its gel-to-solution transition around human body temperature. In this work, we developed a series of F127–gelatin composite hydrogels with reverse thermo-responsive properties. The stiffness of F127–gelatin hydrogels can be adjusted by varying the types and contents of gelatin (type A, GA and type B, GB). The results of rheological data showed that F127–GA gels have higher gel strengths than those of F127–GB, which might be due to different isoelectric points between GA and GB. In addition, F127–gelatin gels showed significant cell viability and biocompatibility for human mesenchymal stem cells, indicating that these discovered hydrogels can serve as potential biomaterials and implantable scaffolds for applications in tissue engineering and regenerative medicine.

Herein, we report a tetraphenylethylene-diglycine (TPE-GG) hydrogelator from a systematic study of TPE-capped dipeptides with various amphiphilic properties. From a chemical design, we found that the hydrogelation of TPE-GG molecules can be utilized to generate supramolecular nanostructures with a large TPE-based nanobelt width (∼300 nm) and lateral dimension ratio (>30 fold). In addition, TPE-GG has the lowest molecular weight and minimum number of atoms compared to any TPE-capped peptide hydrogelator reported to date. This minimal self-assembled hydrogelator can fundamentally achieve the gel features compared with other TPE-capped peptides. A combined experimental and computational study indicates the π-π interactions, electrostatic interactions and hydrogen-bonding interactions are the major driving forces behind the formation of self-assembled nanobelts. This study demonstrates the importance of structure-property relationships and provides new insights into the design of supramolecular nanomaterials.