Cation Tuning toward the Inference of the Gelation Behavior of Supramolecular Gels.

Peng Xue,Yi Zhang,Huiqiong Wu,Jide Wang,Rujuan Shen,Xiaojuan Wang,Fan Yue,Ting He

doi:10.1038/srep25390

Abstract

We serendipitously discovered that the tripeptide Asp–Phe–Phe trifluoroacetic acid salt (hereafter abbreviated as β-AspFF) formed a reversible thermotropic gel in chloroform solution (at temperatures higher than the boiling point of chloroform), and a stable gel in toluene solution (at equal to or lower than the room temperature). Experimental results indicate that doping metal ions into β-AspFF toluene gels can trigger morphological variations in the gel skeleton, thereby increasing gel volume and inducing the collapse of organogels. Investigation on the cation-tuned gelation behavior of β-AspFF can be used to elucidate heating-induced gel collapse (of normal gel) or reverse thermotropic gelation as well as select carbamide and acetamide as activators of β-AspFF gels in chloroform solution at room temperature.

Highlights

Advances in the use of supramolecular gelators for fabrication of polymer-like physical gels have inspired scholars to develop functional soft materials[1,2,3,4,5]
Scanning electron microscopy (SEM) results showed that the β -AspFF toluene gel consists of fibrous networks with entangled long fibrils, with diameters ranging from 50 nm to 100 nm (Figure S2)
This finding was confirmed by transmission electron microscopy (TEM) observations, in which fibrils possess an average diameter of less than 100 nm (Fig. 1a)

Summary

Introduction

Advances in the use of supramolecular gelators for fabrication of polymer-like physical gels have inspired scholars to develop functional soft materials[1,2,3,4,5]. The heat-set, jelly-like networks of LMWGs have attracted intensive attention as novel thermoresponsive materials. The reversible self-assembly of the first thermotropic LMWG is an enthalpically driven process, in contrast to the entropy-driven heat-set gelation of polymers and proteins[12]. Cations or anions are used as a chemical stimulus to effectively elucidate the self-assembly pathway during gelation. The binding effect of cations on supramolecular gels has begun to attract widespread attention[19,20,21,22]. We introduce a facile example of using cations as a chemical stimulus to investigate the structure–activity relationship of a thermotropic gel. The gelator β -AspFF is a tripeptide that contains diphenylalanine (FF) as the assembly core and aspartic acid moiety as the metal binding unit (Figure S1)

Methods

Results

Conclusion