Domination of H-Bond Interactions in the Solvent-Triggering Gelation Process

Abstract

Gels prepared with the solvent-triggering method are attractive for their easy and fast preparation; however, the role of solvents in this process remains unclear, which hinders the efficient and accurate control of desired gel properties. In this study, the role of solvents in the solvent-triggering gelation process is studied using 9-fluorenylmethoxycarbonyl (Fmoc)-protected diphenylalanine (Fmoc-FF) as the gelator. Density functional theory (DFT)-based calculations and corresponding wavefunction analyses are conducted to identify the H-bonding interaction sites between the molecules. The calculation results clearly annotate the activating role of DMF and the triggering role of H 2 O in the gelation process. The solvation of Fmoc-FF by DMF can activate the Hbonding sites on the peptide chain, showing a conformation reversal and higher electrostatic potentials. Then, the H-bonding between Fmoc-FF and H 2 O is facilitated to trigger gelation. The physical Fmoc-FF/DMF/H 2 O gels show easily tuned mechanical strengths (G′ of 10 2 −10 5 Pa), injectable potentials (general yield strain < 100%), and stable recoverability (80−98% within 100 s). The regulation of these properties depends on not only the gelator concentration but also the H-bonding interactions with solvent molecules, which have seldom been studied in detail before. By understanding the effect of solvents, low-molecular-weight gelatorbased gels can be designed, prepared, and tuned efficiently for potential applications.

Jerky-Inspired Fabrication of Anisotropic Hydrogels with Widely Tunable Mechanical Properties

“…We hypothesize that the constant stress had a limited influence on the stiffness of the alginate hydrogels at a high water content. With further water loss, the lateral association of the aligned polymers and network shrinkage led to a rigid improvement in the hydrogels. − Therefore, the tunable anisotropy and water content of hydrogels by the stretching stress could induce different mechanical properties.…”

A co-assembly process for high strength and injectable dual network gels with sustained doxorubicin release performance

“…11,[15][16][17] Furthermore, by adopting a solvent-triggering method, the gel preparation, property-tuning and loading can be easily regulated by solvent ratios, greatly improving the operation efficiency. [18][19][20] It can successfully load DOX as presented in our previous work, showing high gelation efficiency (in 3 seconds) and efficient controlled release of DOX (12 h), as well as injectable and disassembly release abilities. 21 However, pure Fmoc-F gels still show weak gel strength.…”