Abstract
Biomimetic planar artificial membranes have been widely studied due to their multiple applications in several research fields. Their humectation and thermal response are crucial for reaching stability; these characteristics are related to the molecular organization inside the bilayer, which is affected by the aliphatic chain length, saturations, and molecule polarity, among others. Bilayer stability becomes a fundamental factor when technological devices are developed—like biosensors—based on those systems. Thermal studies were performed for different types of phosphatidylcholine (PC) molecules: two pure PC bilayers and four binary PC mixtures. These analyses were carried out through the detection of slight changes in their optical and structural parameters via Ellipsometry and Surface Plasmon Resonance (SPR) techniques. Phospholipid bilayers were prepared by Langmuir-Blodgett technique and deposited over a hydrophilic silicon wafer. Their molecular inclination degree, mobility, and stability of the different phases were detected and analyzed through bilayer thickness changes and their optical phase-amplitude response. Results show that certain binary lipid mixtures—with differences in its aliphatic chain length—present a co-existence of two thermal responses due to non-ideal mixing.
Highlights
The detection of biomacromolecules in solid-liquid interfaces is an important topic that is currently being studied by several research groups [1,2]
Thermal Studies Performed by Ellipsometric and Surface Plasmon Resonance (SPR) Technique
DPPC, DPPC:DMPC and DPPC:DOPC mixtures were studied by SPR technique, permitting the recognition of their molecular movements when they are subjected to stressful conditions, allowing the detection of minimal changes in their refractive index, a characteristic that is intrinsically related to molecular interactions generated into the membrane (Figures 2 and 3)
Summary
The detection of biomacromolecules (like viruses, exosomes, liposomes, and proteins) in solid-liquid interfaces is an important topic that is currently being studied by several research groups [1,2]. Further, the development of integral and stable biomimetic membranes has been a topic widely analyzed by different research groups during the past years These studies have been focused mainly on the modeling of native bilayer membranes with the finality of understanding their behavior under certain conditions and, obviously, with the aim of finding possible scientific applications [8,9]. Small variations in the layer were detected and analyzed through slight thickness changes and phase-amplitude response using Ellipsometry and Surface Plasmon Resonance (SPR) techniques, respectively For this last characterization method, the same ellipsometric equipment was used as a base, but the assembly was slightly modified, including a dove prism into the optical path that permits to obtain a higher resolution and sensitivity in SPR signal detection [40]
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