Hydrogels Consisting of Vesicles Constructed via the Self-Assembly of a Supermolecular Complex Formed from α-Cyclodextrin and Perfluorononanoic Acid

Abstract

The self-assembly of α-cyclodextrin (α-CD) mixed with a fluorocarbon surfactant, perfluorononanoic acid (PFNA), in aqueous solution was studied. Interestingly, the 1:1 inclusion complex, PFNA@α-CD, was verified to form by 1H nuclear magnetic resonance measurement. Also as the building block, the PFNA@α-CD complex was further self-assembled into worm-like micelles under lower concentrations while hydrogels were self-assembled under higher concentrations. The hydrogels were composed of unilamellar vesicles with polydisperse size, which were clearly detected by freeze-fracture transmission electron microscopy measurements. Besides, the vesicle hydrogels showed high viscoelasticities and a substantial elastic characteristic. Also as revealed by the results of Fourier transform infrared measurements, the driving force for the vesicle and worm-like micelle formation was the hydrogen bonding between α-CD molecules. Then, these vesicles were densely packed to form hydrogels. As far as we know, the self-assembly of CDs and fluorocarbon surfactants based on host–guest inclusion in aqueous solution has been limitedly reported. Our work successfully constructed hydrogels consisting of vesicles through the self-assembly of the α-CD/PFNA complex for the first time and will also provide a better understanding and enrich the fundamental research of the self-assembly behavior of the CD/fluorosurfactant complex.

Hierarchical assembly of pH-responsive surfactant–cyclodextrin complexes

“…The truncated cone shape structure with a hydrophilic outer surface and a hydrophobic cavity, ranging from 5 to 8 Å, provide unique physicochemical properties to CDs, particularly the ability to form host-guest complexes. 1 The hydrophobic cavity, hydrophilic rims, the electron density, and the presence of the highenergy water in the cavity drive the assembly with a large range of different molecules, such as drugs, 2 polymers, [3][4][5] and surfactants, 6,7 affecting their properties. 8 In turn, surfactant molecules and amphiphilic polymers self-assemble in aqueous solutions above a defined concentration.…”

Enzyme-Responsive Molecular Assemblies Based on Host–Guest Chemistry

“…CDs are macrocyclic compounds and considered biologically safe. Recent studies have shown that CDs are able to form host–guest complexes by associating with a vast number of commercially available materials. − In particular, we demonstrated previously that β-CD-amphiphile complexes can further assemble into diverse structures, including vesicles, − tubes, − lamellae, − helical ribbons, and rhombics . Because 1,4-glycosidic bonds in CDs can be cleaved by α-amylase, , we are able to construct the CD-based molecular assemblies that may serve as a versatile platform for the development enzyme-responsive systems, especially in the construction of enzyme-responsive assemblies that exhibit structural transitions.…”

Vesicle Hydrogels Formed from the Perfluorononanoic Acid/Tetradecyl Dimethylaminoxide Oxide System

“…The morphology of vesicles reported is usually spherical. Nowadays, increasing interest has been paid to polyhedral vesicles that have been found to be formed from some nonionic surfactant systems and catanionic surfactant mixtures. , However, the hydrogels consisting of polyhedral vesicles have been rarely reported until now. − In our previous work, we systematically studied catanionic fluoro-/hydrocarbon surfactant mixtures with different alkyl chain lengths and found that hydrogels composed of polyhedral vesicles were formed in certain systems. , Therefore, to extend our earlier research about the catanionic fluoro-/hydrocarbon surfactant systems, in this paper, an amphoteric hydrocarbon surfactant, tetradecyl dimethylaminoxide (C 14 DMAO), was chosen to mix with perfluorinated n-nonanoic acid (C 8 F 17 COOH) in an aqueous solution. The phase behavior and rheological properties were investigated.…”