Faceted fatty acid vesicles formed from single-tailed perfluorinated surfactants

Abstract

The aggregation behavior and rheological properties of two mixtures of perfluorononanoic acid (PFNA)/NaOH and perfluorodecanoic acid (PFDA)/NaOH were investigated in aqueous solutions. Interestingly, pH-sensitive polyhedral fatty acid vesicles were spontaneously formed in both systems, which were determined by freeze-fracture transmission electron microscopy (FF-TEM) measurements. Especially, a phase transition from faceted vesicles to the L3 phase with the increase of pH was observed in the PFNA/NaOH system while it was not observed in the PFDA/NaOH system. Differential scanning calorimetry (DSC) and wide angle X-ray scattering (WAXS) measurements confirmed that the bilayers of the faceted vesicles were in the crystalline station indicating that the crystallization of fluorocarbon chains was the main driving force for their formation. Besides, the two systems of faceted perfluorofatty acid vesicles exhibit interesting rheological properties, for instance, they showed high viscoelasticity and shear-thinning behaviour, and the elastic modulus (G') and viscous modulus (G'') of PFDA/NaOH vesicles were much higher than those of PFNA/NaOH vesicles. Conversely, the solution of the L3 phase with fluid bilayers did not present viscoelastic properties. Therefore, the viscoelastic properties of vesicles resulted from the crystalline fluorinated alkyl chains with high rigidity at room temperature and the dense packing of vesicles. As far as we know, such faceted fatty acid vesicles formed from single-tailed perfluorinated surfactants have been rarely reported. Our work successfully constructs polyhedral fatty acid vesicles and proposes their formation mechanism, which should be a great advance in the fundamental research of fatty acid vesicles.

Hydrothermal Preparation of Faceted Vesicles Made of Span 40 and Tween 40 and Their Characterization

“…In contrast, angular vesicles were observed at 0.25 wt% (Figure 5b,c). A cryo-TEM image of Type B vesicles is consistent with the observations previously reported [15][16][17][21][22][23]. The polydispersity indices (PDI) for Types A and B indicated 0.23-0.45 and 0.16-0.28, respectively.…”

“…The faceted vesicle is a polyhedral vesicle that contains membrane defects at the rim of the facets [11]. Such faceted vesicles can be formed from many different materials such as catanionic amphiphiles [12], block copolymers [13], phospholipids [11,14,15], and fatty acid/fluorinated fatty acid systems [16,17], rather than nonionic surfactants such as Span 40/Tween 40 [8]. For example, the mixture of fatty acid and fluorinated fatty acid can yield faceted vesicles by adjusting the pH of the fluorinated fatty acid [16,17].…”

“…Such faceted vesicles can be formed from many different materials such as catanionic amphiphiles [12], block copolymers [13], phospholipids [11,14,15], and fatty acid/fluorinated fatty acid systems [16,17], rather than nonionic surfactants such as Span 40/Tween 40 [8]. For example, the mixture of fatty acid and fluorinated fatty acid can yield faceted vesicles by adjusting the pH of the fluorinated fatty acid [16,17]. Alternatively, a cooling of the temperature to below the phase-transition temperature results in a formation of gel-phase interdigitated membranes and a subsequent phase separation of a flexible rim and stiff facets to induce the faceted vesicles [11,18].…”

Ubidecarenone-Loaded Nanostructured Lipid Carrier (UB-NLC): Percutaneous Penetration and Protective Effects Against Hydrogen Peroxide-Induced Oxidative Stress on HaCaT Cells

“…Freeze-fracture transmission electron microscopy (FF-TEM) was employed to characterize the morphology of UB-NLC [ 40 , 41 , 42 , 43 , 44 ]. For freeze-fracture (FF) measurements, droplets of the sample were dropped onto a specimen holder and frozen via a rapid plunge into liquid nitrogen.…”

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

“…Aggregates formed from perfluorocarbon surfactants have a high application value in drug delivery, blood substitute, etc. , In previous and current study, commercially available fluorinated surfactants, such as fluorocarbon alkyl carboxylate surfactants and perfluoroethercarboxylic acids (PFECAs), have been proved to be most strongly encapsulated by β-CD and form inclusion complexes accordingly. − As far as we know, there are no universally concerns about the self-assembly of such CD/fluorinated surfactant inclusion complexes. Since we have studied the detailed self-assembly of fluorinated fatty acids in the presence of different hydrocarbon surfactants in aqueous solution, − now we are eager to know what kind of aggregate would form through the self-assembly of CD/fluorinated surfactant complexes.…”