INVESTIGADORES
OLIVEIRA Rafael Gustavo
congresos y reuniones científicas
Título:
Myelin monolayers at the air/water interface: physical parameters of coexisting domains
Autor/es:
PUSTERLA JULIO MARTÍN; HERNÁNDEZ, JUAN MARTÍN; BISHOF, ANDREA A.; WILKE, N.; RAFAEL GUSTAVO OLIVEIRA
Lugar:
San Javier, Tucumán
Reunión:
Congreso; XLI Reunión Anual de la Sociedad Argentina de Biofísica; 2012
Institución organizadora:
Sociedad argentina de Biofísica
Resumen:
Myelin membranes spread as Langmuir
monolayers at the air/water interface. They show coexisting domains whose
morphology depends on compression state and ionic character of the subphase.
The equilibrium domain radius was estimated from the transition from circular
to elliptical shapes (1) to be ~70 µm (2). It depends on the competition
between line tension (λ) and dipolar repulsion inside the domains which is
proportional to the dipolar density difference (µ2) between the
phases. In this work we focus on the determination of both parameters.
Line tension was indirectly inferred
for myelin lipid domains, rendering extremely low values (fN range) (3). We
directly measured λ by shape
relaxation methods (4) and found it within 0.65-0.95 pN depending on subphase
conditions. Some authors ascribe ë to the difference in height between the
lipid phases. In order to estimate the difference in height we measured the
reflectivity by Brewster angle microscopy.
The
other force that competes with line tension is dipolar repulsion. We measured
the restricted Brownian motion of trapped domains and, from the distribution of
positions; we calculated µ2 between the phases and found it ranging between
10-40 fN. Having both, λ and µ2, an
equilibrium radius may be approximated.