Supramolecular gel formation regulated by water content in organic solvents: self-assembly mechanism and biomedical applications

• Published in: RSC advances Vol. 11; no. 19; pp. 11519 - 11528
• Main Authors: Liao, Lieqiang, Jia, Xinjian, Lou, Haoxiang, Zhong, Jinlian, Liu, Huijin, Ding, Shunming, Chen, Chao, Hong, Sanguo, Luo, Xuzhong
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 19.03.2021; The Royal Society of Chemistry
• Subjects: Biocompatibility; Biomedical materials; Chemistry; Controlled release; Crystal structure; Crystallography; Endothelial cells; Gels; Hydrogen bonding; Moisture content; NMR; Nuclear magnetic resonance; Self-assembly; Single crystals; Solvents; Supramolecular compounds; Tissue engineering; Xerogels
• ISSN: 2046-2069; 2046-2069
• DOI: 10.1039/d1ra00647a

As one of the most important and fruitful methods, supramolecular self-assembly has a significant advantage in designing and fabricating functional soft materials with various nanostructures. In this research, a low-molecular-weight gelator, N , N ′-di(pyridin-4-yl)-pyridine-3,5-dicarboxamide (PDA-N4), was synthesized and used to construct self-assembled gels via a solvent-mediated strategy. It was found that PDA-N4 could form supramolecular gels in mixed solvents of water and DMSO (or DMF) at high water fraction (greater than or equal to 50%). By decreasing the water fraction from 50% to 30%, the gel, suspension and solution phases appeared successively, indicating that self-assembled aggregates could be efficiently modulated via water content in organic solvents. Moreover, the as-prepared PDA-N4 supramolecular gels not only displayed solid-like behavior, and pH- and thermo-reversible characteristics, but also showed a solution-gel-crystal transition with the extension of aging time. Further analyses suggested that both the crystal and gel had similar assembled structures. The intermolecular hydrogen bonding between amide groups and the π-π stacking interactions between pyridine groups played key roles in gel formation. Additionally, the release behavior of vitamin B12 (VB 12 ) from PDA-N4 gel (H 2 O/DMSO, v/v = 90/10) was evaluated, and the drug controlled release process was consistent with a first-order release mechanism. The human umbilical venous endothelial cell culture results showed that the PDA-N4 xerogel has good cytocompatibility, which implied that the gels have potential biological application in tissue engineering and controlled drug release. Supramolecular hydrogels with solution-gel-crystal transition, pH- and thermo-reversible characteristics were constructed via a solvent-mediated strategy and applied to cell cultivation and controllable drug release.