Numerical investigation of the dynamical behavior of a fluid-filled microparticle suspended in human arteriole

The study of artificial microparticles (capsules and vesicles) has gained a growing interest with the emergence of bioengineering. One of their promoting applications is their use as therapeutic vectors for drug delivery, when capsules and vesicles release their capacity in a targeted environment. The dynamic behavior of capsules and vesicles in confined or unbounded flows was widely studied in the literature and their mechanical response was truthfully described using constitutive laws with good agreement with experiences. However, in a context of biological application, to our knowledge, none of published studies investigating the mechanical response of deformable microparticle took into account the real physiological conditions: the rheological properties of blood such as carrying fluid and the mechanical properties of blood vessels. In this paper, we consider a hyperelastic microparticle suspended in human arteriole. We investigate the deformation of the microparticle resulting from its interaction with blood flow and the arteriolar wall using various capillary numbers and respecting physiological properties of blood and arterial wall. The influence of the blood viscosity model (Newtonian vs shear-thinning) is investigated and a comparison with a rigid microchannel and a muscle-embedded arteriole are carried out. The fluid structure interaction (FSI) problem is solved using Arbitrary Lagrangian Eulerian (ALE) method. Our simulations have revealed that the arteriolar wall distensibility deeply influences both the deformation and velocity of the microparticle: the deformation strongly increases while the velocity decreases in comparison to an infinitely rigid wall. In the context of therapeutic procedure of targeted drug-delivery, a particular attention should be addressed to these observations, in particular for their implication in the burst mechanism

Effect of arteriolar distensibility on the lateral migration of liquid-filled microparticles flowing in a human arteriole

A promising advance of bioengineering consists in the development of micro-nanoparticles as drug delivery vehicles injected intravenously or intraarterialy for targeted treatment. Pro cient functioning of drug carries is conditioned by a reliable prediction of pharma- cokinetics in human as well as their dynamical behavior once injected in blood stream. In this study we aim to provide a reliable numerical prediction of dynamical behavior of microparticles in human arteriole focusing on the crucial mechanism of lateral migration. The dynamical response of the microparticle upon blood flow and arteriolar distensibility is investigated by varying main controlling parameters: viscosity ratio, con nement and capillary number. The influence of the hyperelastic arteriolar wall is highlighted through comparison with an in nitely rigid arteriolar wall. The hydrodynamic interaction in a microparticle train is examined. Fluid-structure interaction is solved by the Arbitrary Lagrangian Eulerian method using the COMSOL Multiphysics software

Supramolecular assembly of gelatin and inorganic polyanions: Fine-tuning the mechanical properties of nanocomposites by varying their composition and microstructure

A series of bionanocomposites has been synthesized through a complex coacervation process inducing the assembly of gelatin with a wide range of inorganic polyanions (IPyAs) differing by their diameter and charge and including polyoxometalates (POMs) and a polythiomolybdate cluster. The microstructure and stoichiometry of these hybrid coacervates, which are strongly dependent on the charge matching between both components, have been studied by combining Fourier transform infrared (FT-IR) spectroscopy, solid-state nuclear magnetic resonance (NMR), thermogravimetric analysis (TGA), elemental analysis, differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) elemental mapping. The mechanical properties of these materials were deeply characterized by tensile measurements at large deformation, revealing different behaviors (i.e., elastomer and ductile), depending on the nature of the IPyA. It is noteworthy that the mechanical properties of these bionanocomposites are strongly enhanced, compared to pure gelatin hydrogels. When attempting to connect structure and properties in these bionanocomposites, we have demonstrated that the density of cross-links (gelatin triple helices and IPyA) is the key parameter to control the extensibility of these materials

Assemblages supramoléculaires entre des clusters thiométallique et polyoxométalliques et un biopolymère pour la construction de matériaux hybrides

L association de clusters inorganiques anioniques de type polyoxométallate ou thiométallate avec un biopolymère, la gélatine, conduit par coacervation complexe à des matériaux composites particulièrement prometteurs. L étude du phénomène de séparation de phase liquide-liquide entre les deux polyélectrolytes de charges opposées ainsi que la caractérisation des coacervats ont été réalisées. Les résultats montrent d une part que le phénomène de coacervation dépend de la charge, de la taille et de la nature des clusters anioniques utilisés et d autre part que l intégrité de ces derniers est maintenue après leur immobilisation dans la matrice gélatine. Les matériaux hybrides gélatine-cluster présentent également des propriétés mécaniques originales proches de celles des élastomères mises en évidence par des essais mécaniques. Enfin, la combinaison de ces deux composantes et d un liquide ionique par dépôt couche sur couche réalisée sur une électrode de carbone a permis l élaboration de matériaux d électrode particulièrement actifs en électrocatalyse.The association of thiometalate or polyoxometalate with a biopolymer, gelatin, by a complex coacervation process leads to hybrid materials with promising properties. The coacervation process with various clusters was studied and we demonstrated that liquid-liquid phase depends on the charge, the size and the nature of the cluster. The coacervate characterization showed that the cluster s integrity was maintained once in gelatin matrix. The study of the materials mechanical properties by tensile test showed that these coacervates present rubber-like behaviour. Finally, we managed to obtain through a layer-by-layer process modified glassy carbon electrodes with electrocatalytic activities.VERSAILLES-BU Sciences et IUT (786462101) / SudocSudocFranceF

Interfacing a heteropolytungstate complex and gelatin through a coacervation process: design of bionanocomposite films as novel electrocatalysts.

International audienceBionanocomposite films on glassy carbon electrodes (GCEs) have been prepared by a very straightforward and reliable method based on a layer-by-layer deposition of polyoxometalate (POM) (i.e. [BW12O40]5−) and gelatin solutions. The strong immobilisation of [BW12O40]5− on the surface of the GCE results from electrostatic interactions between gelatin and POM, as evidenced in a hybrid hydrogel prepared by a coacervation process. The GCE has also been modified by imidazolium based ionic liquids in order to increase the charge transfer rate. Two modified electrodes with one or two POM layers have been prepared by this strategy. When compared to other POM-based modified electrodes, the novel electrodes with two POM layers exhibit excellent electrocatalytic performance for nitrite detection at pH 3 in terms of sensitivity (868 mA M−1 cm−2) and linear range of nitrite concentrations (50-600 μM)