Protein transfer to membranes upon shape deformation

Red blood cells, milk fat droplets, or liposomes all have interfaces consisting of lipid membranes. These particles show significant shape deformations as a result of flow. Here we show that these shape deformations can induce adsorption of proteins to the membrane. Red blood cell deformability is an important factor in several diseases involving obstructions of the microcirculatory system, and deformation induced protein adsorption will alter the rigidity of their membranes. Deformation induced protein transfer will also affect adsorption of cells onto implant surfaces, and the performance of liposome based controlled release systems. Quantitative models describing this phenomenon in biomaterials do not exist. Using a simple quantitative model, we provide new insight in this phenomenon. We present data that show convincingly that for cells or droplets with diameters upwards of a few micrometers, shape deformations induce adsorption of proteins at their interface even at moderate flow rate

Numerical simulations of complex fluid-fluid interface dynamics

Interfaces between two fluids are ubiquitous and of special importance for industrial applications, e.g., stabilisation of emulsions. The dynamics of fluid-fluid interfaces is difficult to study because these interfaces are usually deformable and their shapes are not known a priori. Since experiments do not provide access to all observables of interest, computer simulations pose attractive alternatives to gain insight into the physics of interfaces. In the present article, we restrict ourselves to systems with dimensions comparable to the lateral interface extensions. We provide a critical discussion of three numerical schemes coupled to the lattice Boltzmann method as a solver for the hydrodynamics of the problem: (a) the immersed boundary method for the simulation of vesicles and capsules, the Shan-Chen pseudopotential approach for multi-component fluids in combination with (b) an additional advection-diffusion component for surfactant modelling and (c) a molecular dynamics algorithm for the simulation of nanoparticles acting as emulsifiers.Comment: 24 pages, 12 figure

Effect of copper ions on the drainage stability of foams prepared from egg white

In this paper we investigate the effect of copper ions on the stability of foams prepared from egg white. We compare the time of formation and stability of foams prepared from fresh egg whites, with and without added copper ions. We find that the foams prepared with copper ions take more time to form, but are more stable. The effect increases upon dilution of the egg whites, which shows that the bulk phase is not responsible for the increase in stability. Microscopy shows that the initial bubble size distribution of the foam is not affected by the addition of copper ions. Measurements with a ring trough show that the surface tension of the liquid vapor interface of the foam films is also unaffected. The results of the ring trough measurements show that the increase in drainage stability is caused mainly by an increase in the surface dilatational elasticity of the interface. There is also an increase in the surface dilatational viscosity, but only at frequencies less than 0.1 Hz. The increase in the surface dilatational elasticity affects the drainage stability of the foam during the initial seconds of the drainage process, whereas the increase in the surface dilatational viscosity affects the long-term drainage stability

Effect of copper ions on the drainage stability of foams prepared from egg white

In this paper we investigate the effect of copper ions on the stability of foams prepared from egg white. We compare the time of formation and stability of foams prepared from fresh egg whites, with and without added copper ions. We find that the foams prepared with copper ions take more time to form, but are more stable. The effect increases upon dilution of the egg whites, which shows that the bulk phase is not responsible for the increase in stability. Microscopy shows that the initial bubble size distribution of the foam is not affected by the addition of copper ions. Measurements with a ring trough show that the surface tension of the liquid vapor interface of the foam films is also unaffected. The results of the ring trough measurements show that the increase in drainage stability is caused mainly by an increase in the surface dilatational elasticity of the interface. There is also an increase in the surface dilatational viscosity, but only at frequencies less than 0.1 Hz. The increase in the surface dilatational elasticity affects the drainage stability of the foam during the initial seconds of the drainage process, whereas the increase in the surface dilatational viscosity affects the long-term drainage stability

Protein transfer to membranes upon shape deformation

Red blood cells, milk fat droplets, or liposomes all have interfaces consisting of lipid membranes. These particles show significant shape deformations as a result of flow. Here we show that these shape deformations can induce adsorption of proteins to the membrane. Red blood cell deformability is an important factor in several diseases involving obstructions of the microcirculatory system, and deformation induced protein adsorption will alter the rigidity of their membranes. Deformation induced protein transfer will also affect adsorption of cells onto implant surfaces, and the performance of liposome based controlled release systems. Quantitative models describing this phenomenon in biomaterials do not exist. Using a simple quantitative model, we provide new insight in this phenomenon. We present data that show convincingly that for cells or droplets with diameters upwards of a few micrometers, shape deformations induce adsorption of proteins at their interface even at moderate flow rates