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La transición controlada por contraperiones de un gemelo catiónico de las vesículas submicroscópicas a las gigantes
Samppa J Ryhänen1, V Matti J Säily, Mikko J Parry
1Helsinki Biophysics and Biomembrane Group, Institute of Biomedicine/Biochemistry, Biomedicum, University of Helsinki, P.O. Box 63 (Haartmaninkatu 8), FIN-00014, Finland.
Journal of the American Chemical Society
|June 29, 2006
Resumen
Los investigadores descubrieron un lípido catiónico gemini que las transiciones entre las vesículas pequeñas y gigantes (GVs) en función de la concentración de sal y la temperatura, revelando complejas estructuras biológicas de tipo membrana.
Área de la Ciencia:
- Se trata de una química supramolecular.
- Ciencia de los materiales ciencia de los materiales.
- La biofísica es la biofísica.
Sus antecedentes:
- El autoensamblaje de lípidos se entiende a nanoescala, pero la organización a mesoescala relevante para la biología es menos clara.
- Los lípidos catiónicos gemini son moléculas anfifílicas con aplicaciones potenciales en sistemas biomiméticos.
Objetivo del estudio:
- Para investigar el autoensamblaje a mesoescala de un lípido catiónico gemini.
- Comprender los factores que influyen en la formación y morfología de las vesículas lipídicas.
- Para dilucidar el mecanismo detrás de las transiciones morfológicas observadas.
Principales métodos:
- Experimentos de microscopía (por ejemplo, cryo-TEM, AFM) para observar las estructuras de los lípidos.
- Variación de la concentración de cloruro de sodio (NaCl) y la temperatura para estudiar las transiciones de fase.
- Construcción de un diagrama de fase tentativo basado en observaciones experimentales.
Principales resultados:
- Se observó una transición aguda y reversible de vesículas pequeñas (~ 40 nm) a vesículas gigantes (GVs, ~ 11 μm).
- Esta transición es dependiente de la concentración de NaCl y la temperatura.
- Estructuras mesoescalares complejas que se asemejan a membranas biológicas formadas cerca de la interfaz aire/agua por debajo de la transición.
- Se construyó un diagrama de fase tentativo de concentración de NaCl frente a la temperatura.
Conclusiones:
- Se propuso un nuevo mecanismo que involucra la interacción específica de Cl(-) conterión con el tensioactivo catiónico gemini.
- Esta interacción conduce a una red de contrión de soluto con baja curvatura espontánea, lo que influye en la organización de los lípidos.
- La red iónica controla efectivamente la curvatura de la membrana y la organización tridimensional a mesoescala del lípido, imitando el comportamiento de la membrana biológica.
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