Gonçalves da Silva AMPS. Interaction of Hydrophobic Ionic Liquids with Lipids in Langmuir Monolayers.
LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018;
34:3797-3805. [PMID:
29518336 DOI:
10.1021/acs.langmuir.7b04164]
[Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The interaction of two ionic liquids, trihexyl(tetradecyl)phosphonium bis(trifluoromethylsulfonyl)-imide and trihexyl(tetradecyl)phosphonium dicyanamide, [P6 6 6 14][Ntf2] and [P6 6 6 14]/[N(CN)2], with several long-chained lipids with a different net charge at the hydrophilic group, a cationic surfactant, dioctadecyldimethylammonium bromide (DODAB), a zwitterionic phospholipid (DPPC), an anionic phospholipid (DPPG), and the neutral stearic acid (SA), was investigated at the air-water interface using the Langmuir trough technique. The experimental surface pressure-area (π- A) isotherms obtained for selected compositions of each binary system reveal distinct interfacial behavior. The degree and the nature of the IL-lipid interaction strongly depend on the charge distribution in the lipid polar group. Miscibility, or immiscibility, at the monolayer was inferred from the comparison of the experimental π- A isotherm with the theoretical curve calculated for the corresponding ideal mixture based on the π- A isotherms of the pure components. Phase separation and partial miscibility occurred in IL/DODAB and IL/DPPC systems, respectively. In both the IL/DPPG and the IL/SA systems, a new catanionic complex was found. For the IL/SA system, the catanionic complex formation varies with the subphase pH.
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