New multifunctional textile biomaterials for the treatment of leg venous insufficiency.

Acryloyl monomers have been synthesized by reaction of beta-cyclodextrin and troxerutin with acryloyl chloride and grafted on a knitted material obtained from polyamide 6.6 and polyurethane fibers. Polyamide grafted with beta-cyclodextrin derivative binds troxerutin as a physical complex. The obtained biomaterials have been tested in vivo on rats for their ability to deliver troxerutin (a flebotonic drug) to different skin areas (epidermis, dermis and vascular wall). The results showed that the new synthesized materials can act as multifunctional bioactive textiles that can display both compression (given by the textile material) and sustained venotonic and haemostatic properties (given by the troxerutin delivered from biomaterial to the skin).

A novel multicompartimental system based on aminated poly(vinyl alcohol) microspheres/succinoylated pullulan microspheres for oral delivery of anionic drugs.

Poly(vinyl alcohol) (PVA) microspheres were prepared by dispersion reticulation with glutaraldehyde and further aminated. These microspheres were firstly loaded with diclofenac (DF) and then entrapped in cellulose acetate butyrate (CAB) microcapsules by an o/w solvent evaporation technique for intestinal delivery of drug. The encapsulated PVA microspheres due to their low swelling degree in intestinal fluids, do not have enough force to produce the disruption of CAB shell, therefore different amounts of succinoylated pullulan microspheres (SP-Ms) (exchange capacity up to 5.2 meq/g) were co-encapsulated. The SP-Ms do not swell in acidic pH, but swell up to 20-times in intestinal fluids causing the rupture of CAB shell and facilitating the escape of loaded PVA microspheres.

Aminated polysaccharide microspheres as DNA delivery systems.

This article describes the production and characterization of cationic microparticles based on pullulan and starch for the delivery of nucleic acids. The microparticles were prepared by chemically cross-linkinking of a polymer solution dispersed in organic phase, followed by amination with N, N-diethyl-2-chloroethyl amine hydrochloride, or N-glycidyl-N,N-dimethyl-N-methylammonium chloride. The association of desoxyribonucleotide (DNA) with positively charged microparticles was determined. The association capacity and the affinity of microspheres for DNA were investigated as a function of type of polysaccharide, content and basicity of the amino groups. It was found that the both types of carriers synthetized display a high affinity for defibrotide due to the high porosity of polysaccharide microspheres (PMs). The in vitro release kinetics from microspheres showed an initial fast release of DNA (30 min) followed by slower release rate over 14 days. DNA release was influenced by the ionic strength of the receiving fluid. In addition, DNA release was slightly more rapid from pullulan than from starch complexes. DNA stability studies were performed by agarose gel, indicating no degradation even after 14 days. All the produced cationic microspheres were able to quantitatively load DNA. The release of DNA from PMs was strongly affected by the ionic strength of the receiving fluid. Finally, agarose gel electrophoresis of DNA released from microspheres indicated that no DNA degradation occurs even after 14 days of release from PMs.

Acrylic microspheres for oral controlled release of the biguanide buformin.

Spherical microparticles based on methacrylic acid-methyl methacrylate copolymer have been developed. The method chosen for the preparation of such microparticles was suspension radical copolymerization of acrylic comonomers in the presence of the ethyleneglycol dimethacrylate as crosslinking agent. The microparticles obtained were characterised by inverse size exclusion chromatography, scanning electron microscopy, swelling degree and exchange capacity. The porous volume of the microspheres ranged from 0.086 ml/g for the microparticles produced by a methacrylic acid/methyl methacrylate ratio of 1/3 and a 10% degree of crosslinking, to 8.57 ml/g for the microparticles produced by a methacrylic acid/methyl methacrylate ratio of 3/1 and 2% degree of crosslinking (in 0.1 N NaCl in phosphate buffer pH 7.4). Also the pore diameter of the swollen microparticles ranged from a few to 120 A. Buformin tosylate - a classical hypoglycaemic drug - was included in the polymer network of the microparticles during the polymerization process. Due to the water solubility of the drug and its low solubility in the organic phase, the entrapment yield did not exceed 15%. However the amount of encapsulated drug as well as the drug released from the microparticles, was dependent on the methacrylic acid/methyl methacrylate ratio, the degree of crosslinking and solvent/comonomers ratio.

Physico-chemical characterization of Ca-alginate microparticles produced with different methods.

In the present paper the physico-chemical characterization of Ca-alginate microparticles produced with different methods is presented. Ca-alginate microparticles were obtained either by emulsification method or by dripping an aqueous alginate solution into a solution of calcium salt. Inverse Size Exclusion Chromatography (ISEC) was used for the determination of dimensions of the pores and porous volume of microparticles having a mean diameter of 220 microm when obtained by emulsification method. The same technique was used to study the variation of the pore size and porous volume with pH. The results were related with the content of calcium and sodium in the microparticles, before and after their treatment with different HCl solutions. For the particles with a mean diameter of 1.2 mm (obtained by dripping method) we adopted an other approach based on the steric exclusion of solute at equilibrium. For a convenient interpretation of the obtained data, determination of water regain, swelling degree, and scanning electron microscopy (SEM) were performed. Finally, a comparison of the characteristics of microparticles produced by ionic and epichlorohydrin crosslinkings was made. The maximum dimensions of the pores of the microparticles obtained by emulsification were found smaller than those obtained by other technics. The variation of the dimensions of the pores and porous volume with pH is not significant. The structure of the chemically crosslinked beads with epichlorohydrin is more elastic and the swelling is reversible; after drying and reswelling process, the dimensions of the pores and porous volume of these microparticles remain unchanged. On the opposite, for the microparticles obtained by emulsification or dripping method in the presence of calcium ions, these characteristics are changed after a first drying process.