Structural features of interfacially adsorbed acyl-l-carnitines.
Huayang Liu1, Ke Fa1, Xuzhi Hu1
1Biological Physics Laboratory, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK.
Journal of Colloid and Interface Science
|May 20, 2022
Summary
Acyl-l-carnitines form sandwich bilayers at solid-liquid interfaces, with layer thickness dependent on acyl chain length. pH and ionic strength influence adsorption structure and thickness, crucial for biosurfactant applications.
Area of Science:
- Surface Chemistry
- Materials Science
- Biotechnology
Background:
- Acyl-l-carnitines (CnLCs) show promise as biocompatible biosurfactants for drug delivery and tissue engineering.
- Understanding their interfacial behavior at solid-liquid interfaces is crucial for technological applications, but remains largely unexplored.
Purpose of the Study:
- To investigate the adsorption behavior of acyl-l-carnitines (CnLCs) at a hydrophilic solid/liquid interface.
- To characterize the structure and thickness of adsorbed CnLC layers under varying pH and ionic strength conditions.
Main Methods:
- Utilized spectroscopic ellipsometry (SE) for dynamic adsorption analysis.
- Employed neutron reflection (NR) for structural determination of adsorbed layers.
- Studied CnLCs (n=12, 14, 16) at the SiO2/water interface.
Main Results:
- At neutral pH, CnLCs formed sandwich bilayers with head-tail-head structures, layer thickness increasing with acyl chain length.
- Acidic conditions led to protonation, increased head group repulsion, and formation of distinct aggregates with reduced layer thickness.
- High ionic strength screened repulsion, enhanced adsorption, and diminished pH effects.
Conclusions:
- The adsorption of CnLCs at the hydrophilic SiO2/water interface is dependent on pH and ionic strength.
- The findings provide fundamental insights into CnLC interfacial behavior, guiding their application in solid-substrate systems.
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