Polymerization kinetics of a mixture of Lipiodol and Glubran 2 cyanoacrylate glue upon contact with a proteinaceous solution.

The Glubran 2 cyanoacrylate glue is a liquid embolic agent used to block blood vessels endovascularly. Typically mixed with an iodized oil (Lipiodol) for visualization under X-ray, it polymerizes when in contact with blood and tissues owing to the presence of ions and proteins. The objective of the study is to determine the influence of plasma proteins in the polymerization reaction.

Polymerization kinetics of n-butyl cyanoacrylate glues used for vascular embolization.

Vascular embolization is a minimally invasive treatment used for the management of vascular malformations and tumors. It is carried out under X-ray by navigating a microcatheter into the targeted blood vessel, through which embolic agents are delivered to occlude the vessels. Cyanoacrylate liquid glues have been widely used for vascular embolization owing to their low viscosity, rapid polymerization/solidification rate, good penetration ability and low tissue toxicity.

Transient behavior and relaxation of microcapsules with a cross-linked human serum albumin membrane.

Capsules consist of droplets enclosed by a membrane with shear resistant properties especially when fabricated by interfacial cross-linking. In many applications, the protection and release of the internal medium need to be strictly controlled. It is possible to tune the membrane mechanical properties by changing the physico-chemical conditions of the fabrication process, but a good control of the production requires their characterization, which is a scientific challenge, since the objects are a few tens of microns in size at most.

Characterizing the membrane properties of capsules flowing in a square-section microfluidic channel: effects of the membrane constitutive law.

A microfluidic method is presented to measure the elastic membrane properties of a population of microcapsules with diameter of order 60 μm. The technique consists of flowing a suspension of capsules enclosed by a polymerized ovalbumin membrane through a square-section microfluidic channel with cross dimension comparable with the capsule mean diameter. The deformed profile and the velocity of a given capsule are recorded.

Tension of red blood cell membrane in simple shear flow.

When a red blood cell (RBC) is subjected to an external flow, it is deformed by the hydrodynamic forces acting on its membrane. The resulting elastic tensions in the membrane play a key role in mechanotransduction and govern its rupture in the case of hemolysis. In this study, we analyze the motion and deformation of an RBC in a simple shear flow and the resulting elastic tensions on the membrane.

Comparison between spring network models and continuum constitutive laws: application to the large deformation of a capsule in shear flow.

A capsule is a liquid drop enclosed by a solid, deformable membrane. To analyze the deformation of a capsule accurately, both the fluid mechanics of the internal and external fluids and the solid mechanics of the membrane must be solved precisely. Recently, many researchers have used discrete spring network models to express the membrane mechanics of capsules and biological cells.

Comparison between measurements of elasticity and free amino group content of ovalbumin microcapsule membranes: discrimination of the cross-linking degree.

An inverse method is used to characterize the membrane mechanical behavior of liquid filled microcapsules. Cross-linked ovalbumin microcapsules are flowed and deformed into a cylindrical microchannel of comparable size. The deformed shape is compared to predictions obtained numerically when modeling a capsule under the same flow conditions.

Mechanical properties of alginate beads hosting hepatocytes in a fluidized bed bioreactor.

Fluidized bed bioartificial liver has been proposed as a temporary support to bridge patients suffering from acute liver failure to transplantation. In such a bioreactor, alginate beads hosting hepatocytes are in continuous motion during at least six hours. After having shown in vitro the functionality of such a device, the present study aims at analyzing the potential mechanical alterations of the beads in the bioreactor, perfused by different surrounding media.

Identification of the elastic properties of an artificial capsule membrane with the compression test: effect of thickness.

The mechanical properties of a capsule membrane are evaluated by means of a compression experiment between two parallel plates. Since large deformations of the membrane are involved, the choice of the wall material constitutive law is essential. In this paper, we explore different classical laws to describe the behavior of the membrane and evaluate also the limit of application of the thin shell approximation.

Deformation and bursting of nonspherical polysiloxane microcapsules in a spinning-drop apparatus.

We analyze the deformation and bursting process of nonspherical organosiloxane capsules in centrifugal fields. Measurements were performed in a commercial spinning-drop tensiometer at different values of tube rotation. A theoretical analysis of the mechanics of initially ellipsoidal elastic shells subjected to centrifugal forces is developed where the deformation of the capsule is predicted as a function of the initial geometry and membrane elastic properties.

Compression of biocompatible liquid-filled HSA-alginate capsules: determination of the membrane mechanical properties.

Compression experiments between two parallel plates are performed on a series of biocompatible HSA-alginate capsules with two different membrane thicknesses. The capsule geometry and size as well as the average membrane thickness are first measured. The compression set-up is fitted with a sensitive force transducer that allows measurement of the compression force as a function of plate separation.

Swelling of hydrocolloid dressings.

Wound healing is promoted by dressings that maintain a moist environment. Specifically, hydrocolloid dressings allow excess fluid to escape without permitting wound desiccation. However, the fluid handling capacity of hydrocolloid dressings depends on many factors such as the physicochemical properties of the gel formulation, and the design of the dressing.

Theoretical modelling of the motion and deformation of capsules in shear flows.

Mechanical models for capsules freely suspended in another liquid, are devised to predict the deformation, motion, breakup of one particle and also the rheological flow behaviour of a suspension. The capsule is filled with a newtonian liquid, and is surrounded by a thin deformable membrane having otherwise arbitrary mechanical properties. Initially spherical capsules in simple shear flow, are found to deform and orient with respect to streamlines, while their membrane is continuously rotating around the internal liquid.

Viscous filtration of red blood cell suspensions.

Filtration experiments on red blood cell suspensions are usually conducted in a saline buffer solution. As a result, the flow of a particle in a pore is largely dominated by viscous effects, and it is not possible to distinguish between normal and membrane altered cells. A new approach to red cell filtration is proposed here, whereby the cells are suspended in a Dextran solution that has roughly the same viscosity as the internal hemoglobin solution.

Determination of the red blood cell apparent membrane elastic modulus from viscometric measurements.

Rhelogical measurements on a dilute suspension of red blood cells (RBCs) are interpreted by means of a microheological model that relates the shear evolution of the apparent viscosity to the intrinsic properties of the suspended particles. It is then possible to quantify the average deformability of a RBC population in terms of a mean value of the membrane shear elastic modulus, Es. Dilute suspensions of erthrocytes exhibit shear-thinning behavior with a constant high shear viscosity.