Dataset Information

Probing Water State during Lipidic Mesophases Phase Transitions.

ABSTRACT: We investigate the static and dynamic states of water network during the phase transitions from double gyroid ( Ia3‾d ) to double diamond ( Pn3‾m ) bicontinuous cubic phases and from the latter to the reverse hexagonal (H_II ) phase in monolinolein based lipidic mesophases by combining FTIR and broadband dielectric spectroscopy (BDS). In both cubic(s) and H_II phase, two dynamically different fractions of water are detected and attributed to bound and interstitial free water. The dynamics of the two water fractions are all slower than bulk water due to the hydrogen-bonds between water molecules and the lipid's polar headgroups and to nanoconfinement. Both FTIR and BDS results suggest that a larger fraction of water is hydrogen-bonded to the headgroup of lipids in the H_II phase at higher temperature than in the cubic phase at lower temperature via H-bonds, which is different from the common expectation that the number of H-bonds should decrease with increase of temperature. These findings are rationalized by considering the topological ratio of interface/volume of the two mesophases.

SUBMITTER: Yao Y

PROVIDER: S-EPMC9298331 | biostudies-literature | 2021 Nov

REPOSITORIES: biostudies-literature

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Probing Water State during Lipidic Mesophases Phase Transitions.

Yao Yang Y Catalini Sara S Kutus Bence B Hunger Johannes J Foggi Paolo P Foggi Paolo P Mezzenga Raffaele R

Angewandte Chemie (International ed. in English) 20211022 48

We investigate the static and dynamic states of water network during the phase transitions from double gyroid ( Ia3‾d ) to double diamond ( Pn3‾m ) bicontinuous cubic phases and from the latter to the reverse hexagonal (H<sub>II</sub> ) phase in monolinolein based lipidic mesophases by combining FTIR and broadband dielectric spectroscopy (BDS). In both cubic(s) and H<sub>II</sub> phase, two dynamically different fractions of water are detected and attributed to bound and interstitial free water. ...[more]

PMID: 34558162

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Project description:Lipidic mesophases are a class of highly ordered soft materials that form when certain lipids are mixed with water. Understanding the relationship between the composition and the microstructure of mesophases is necessary for fundamental studies of self-assembly in amphiphilic systems and for applications, such as the crystallization of membrane proteins. However, the laborious formulation protocol for highly viscous mesophases and the large amounts of material required for sample formulation are significant obstacles in such studies. Here we report a microfluidic platform that facilitates investigations of the phase behavior of mesophases by reducing sample consumption 300-fold, and automating and parallelizing sample formulation. The mesophases were formulated on-chip using less than 80 nL of material per sample and their microstructure was analyzed in situ using small-angle X-ray scattering (SAXS). The 220 μm-thick X-ray compatible platform was comprised of thin polydimethylsiloxane (PDMS) layers sandwiched between cyclic olefin copolymer (COC) sheets. Uniform mesophases were prepared using an active on-chip mixing strategy coupled with periodic cooling of the sample to reduce viscosity. We validated the platform by preparing and analyzing mesophases of the lipid monoolein (MO) mixed with aqueous solutions of different concentrations of β-octylglucoside (βOG), a detergent frequently used in membrane protein crystallization. Four samples were prepared in parallel on chip, by first metering and automatically diluting βOG to obtain detergent solutions of different concentration, then metering MO, and finally mixing by actuation of pneumatic valves. Integration of detergent dilution and subsequent mixing significantly reduced the number of manual steps needed for sample preparation. Three different types of mesophases typical for MO were successfully identified in SAXS data from on-chip samples. Microstructural parameters of identical samples formulated in different chips showed excellent agreement. Phase behavior of samples on-chip (~80 nL per sample) corresponded well with that of samples prepared via the traditional coupled-syringe method using at least two orders of magnitude more material ("off-chip", 35-40 μL per sample), further validating the applicability of the microfluidic platform for on-chip characterization of mesophase microstructure.

Dataset Information

Probing Water State during Lipidic Mesophases Phase Transitions.

Publications

Probing Water State during Lipidic Mesophases Phase Transitions.

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