Louis Danicher

In vitro uptake evaluation in Caco-2 cells and in vivo results in diabetic rats of insulin-loaded PLGA nanoparticles.

PLGA nanoparticles (NPs) are largely developed for biological applications but little is known about their uptake. Therefore, we focused our study on the modalities of insulin-loaded PLGA NPs transport across Caco-2 monolayers, and their hypoglycaemic effect on diabetic rats. Insulin-loaded PLGA NPs were formulated by a double emulsion solvent evaporation process. NPs mean diameter was between 130 and 180 nm. NPs were smooth and spherical with an entrapment efficiency above 80%. Fluorescently labeled NPs were incubated with Caco-2 cells to study the process of uptake and the intracellular fate by flow cytometry and confocal laser scanning microscopy. The kinetic of absorption was time-dependent and occurred by clathrin-mediated endocytosis. The intracellular traffic led to a basolateral exocytosis of NPs. In vitro studies and in vivo intraduodenal administration to diabetic rats showed that NPs were resistant in intestinal conditions long enough to allow both the intestinal absorption of NPs and the delivery of functional insulin in bloodstream. The resulting in vivo hypoglycaemic effect was similar to a long-acting insulin one. As no effect on glycaemia occurred after oral administration, further studies need to be conducted to protect NPs from the degradation occurring at the enteric level.

Size effect of complexing microcapsules on copper ion extraction

Abstract In a previous work [J. Microencapsulation, in press], polyamide microcapsules containing a poly(acrylic acid) gel as a macromolecular ligand (PAA-CAPS) with a mean diameter of 210 μm were prepared using an original two-step polymerization process combining interfacial polycondensation and radical polymerization in a water in oil inverse emulsion system. Extractions of many divalent cations were examined. In this work, we proposed to synthesise by the same process, smaller microcapsules with a mean diameter of 10 μm (PAA-μCAPS). Reference polyamide microcapsules, i.e. without ligand were also synthesized (μCAPS) and (CAPS) [J. Microencapsulation, in press]. Microcapsule wall thickness was evaluated by SEM and TEM observations of microcapsule cross-section cuts, microcapsule water content was determined by thermogravimetric experiments. Specific surface area and total volume of the pore of microcapsules were determined by BET method based on N2 adsorption/desorption. The comparison of the extractabilities and the stripping of Cu(II) into the various kind of microcapsules were examined.

Extraction of metal cations by polyterephthalamide microcapsules containing a poly(acrylic acid) gel

Polyterephthalamide microcapsules containing a poly(acrylic acid) gel as a macromolecular ligand (PAA-CAPS) were prepared using an original two step polymerization process in a water-in-oil inverse emulsion system. A polyamide microcapsule containing acrylic acid, initiator and cross-linking agent, is formed by interfacial polycondensation of terephthaloyl dichloride with hexamethylenediamine. In situ radical polymerization of the microcapsule core acrylic acid is initiated to obtain encapsulated poly(acrylic acid) gel. Reference polyamide microcapsules, i.e. without ligand (CAPS), were also synthesized. The mean diameter of synthesized microcapsules was 210 #181;m, and the microcapsule wall thickness was evaluated by SEM and TEM observations of microcapsule cross-section cuts. The microcapsule water content was determined by thermogravimetric experiments. The extractabilities of Cu(II), Ni(II), Co(II) and Zn(II) into PAA-CAPS were examined. The stripping of the various cations can be promoted in diluted hydrochloric acid solutions.

Model capsules: I. Synthesis, characteristics and properties of millimetric polyamide capsules

Polyamide model capsules (millicapsules) are synthesized by interfacial polymerization. An adapted apparatus has been perfected in order to obtain easy handling capsules (diameter between 1.2 and 4.5 mm) with or without surfactant. The polymer weight composition with regard to the capsule mass, the influence of the surfactant, the growing time and the concentration and the nature of the reagents on the thickness and the surface state of the capsules wall are determined. SEM observations of the internal and external surface of the membrane allows one to follow the progress of its development as a function of the polymerization time. Measurements of the permeability by macromolecules crossing through the millicapsules membrane as well as mechanical resistance by determination of the rupture strength have been made on well-defined capsules.

Preparation of polystyrene-co-divinylbenzene microspheres with controlled sizes by polymerization of stabilized microsuspensions

Abstract The preparation in two steps of polystyrene- co -divinylbenzene microbeads with controlled sizes in the range 2–20 μm diameter has been studied. A stable microsuspension of the monomers is first achieved in water at room temperature and under high shear using different steric stabilizers with or without co-stabilizers. Then, the system is polymerized using free radical initiators to form microbeads in high yield (85%). The conditions to control the characteristics of the microsuspensions have been studied. It has been shown that the microsuspensions when properly stabilized can be polymerized without noticeable change of their size and size distribution, forming microbeads free of adhering emulsion particles. However, a study of the evolution of the size and size distribution of the particles during polymerization shows that the percentage of particles with higher diameters increases slowly during the polymerization in spite of the rapid gelling process. This suggests a mechanism in which the small amount of monomers dissolved in the water phase is preferably adsorbed by those larger particles probably more poorly protected by the steric stabilizer than the finer beads.

Metallic particles from complexing microcapsules dispersed in a silica gel

A new process to control the distribution of metal nanoparticles is proposed. It involves the use of complexing microcapsules obtained by interfacial polycondensation. The latter are hollow spheres constituted of a polymer membrane, containing an insoluble active ingredient, such as a polyacrylic acid, which can complex Co2+ ions. These capsules are dispersed in a silica sol followed by thermal treatments and reduction under H2 which results in metallic Co nanoparticles confined in the capsules domains. The particles do not diffuse in the matrix.

P164 Insuline orale : pharmacocinétique et biodisponibilité de nanoparticules d’insuline administrées par voie intraduodénale

Introduction Nous avons formule de l’insuline administrable par voie orale grâce a un systeme compose d’une gelule gastroresistante contenant des nanoparticules d’insuline rapide (protection intestinale et vecteur de l’insuline au travers de la muqueuse intestinale). L’administration intraduodenale (ID) des nanoparticules (NP) a des rats diabetiques induit une normoglycemie au bout de 9 h Ce travail a consiste a determiner la biodisponibilite de l’insuline encapsulee administree par voie ID. Ceci a aussi ete realise avec des NP de peptide C, peptide peu sujet a l’hemolyse et ayant une extraction hepatique tres faible. Materiels et Methodes La voie de reference choisie pour determiner la biodisponibilite a ete la voie intraperitoneale (IP) car elle assure un premier passage hepatique de la quasi-totalite des peptides utilises. Des rats ont recu 0,165 mg/kg d’insuline ou de peptide C en solution en IP. D’autres ont recu via des catheters implantes dans le duodenum 1,65 mg/kg d’insuline ou de peptide C encapsules. L’insulinemie et la C peptidemie ont ete doses sur 12 h a partir de sang carotidien. Les biodisponibilites (B) ont ete calculees a partir des surfaces sous les courbes (SSC) d’apres la formule : B = (SSCID X DoseIP)/ (SSCIP X Dose ID) X 100. Resultats Apres administration ID de nanoparticules d’insuline, un pic de 230 ± 200 mUI/L (n = 8) a ete observe 1 h apres administration. L’insuline humaine n’est plus decelee 3 h apres administration et B Discussion L’extraction hepatique de l’insuline liberee des NP induit une perte d’information concernant l’insulinemie dosee dans le sang peripherique. De par sa quasi-absence d’extraction hepatique, le peptide C a ete un candidat interessant pour apprehender la pharmacocinetique et la biodisponibilite d’un principe actif encapsule dans nos NP. La diminution de la glycemie anterieurement obtenue apres administration ID de NP d’insuline est concomitante a une elevation de la concentration plasmatique du principe actif encapsule. Conclusion L’absorption des NP par vagues successives expliquerait l’obtention d’un profil glycemique similaire a celui d’une insuline lente.