Synthesis, characterization and platelet adhesion studies of novel ion-containing aliphatic polyurethanes

Synthesis, platelet adhesion and cytotoxicity studies of new glycerophosphoryl-containing polyurethanes

In this work we synthesized new MDI -based poly(ether)urethanes (PEUs) with phospholipid-like residue as chain extender. Polymers were prepared by a conventional two-step solution polymerization procedure using 4,4' diphenylmethanediisocyanate (MDI) and poly(1,4- butanediol) with 1000 as molecular weight to form prepolymers which were successively polymerized with 1 glycerophosphorylcholine (1-GPC), 2-glycerophosphorylcholine (2-GPC) or glycerophosphorylserine (GPS) as chain extenders. Two reference polymers bearing 1,4-butandiol (BD) have been also synthesized. The polymers obtained were characterized by Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC) and modulated scanning calorimetry (MDSC). The biocompatibility of synthesized segmented polyurethanes was then investigated by platelet-rich plasma contact studies and related scanning electron microscopy (SEM) photographs for blood compatibility and cytotoxicity assay (MTT test) on material elution to assess the effect of any toxic leachables on cellular viability. Three polymers among all have given very satisfactory results suggesting to investigate more deeply their possible use in biomedical devices.

Macroporous hydrogels based on 2-hydroxyethyl methacrylate. Part 5: hydrolytically degradable materials

Macroporous hydrogels based on 2-hydroxyethyl methacrylate, 2-ethoxyethyl methacrylate and N-(2-hydroxypropyl)methacrylamide, methacrylic acid and [2-(methacryloyloxy)ethyl]trimethylammonium chloride crosslinked with N,O-dimethacryloylhydroxylamine were prepared. Hydrogels were degraded in a buffer of pH 7.4. Completely water-soluble polymers were obtained over time periods ranging from 2 to 40 days. The process of degradation was followed gravimetrically and by optical and electron microscopy. In vivo biological tests with hydrogels based on copolymers of 2-ethoxyethyl methacrylate/N-(2-hydroxypropyl)methacrylamide were performed.

Hemocompatibilty of new ionic polyurethanes: influence of carboxylic group insertion modes

New segmented polyurethane (PU) anionomers based on hydroxytelechelic polybutadiene (HTPB) were synthesized via two environment-friendly chemical routes. The effects of carboxylic content and ion incorporation mode on the surface properties were investigated by mean of water absorption analysis and static contact angle measurements using water, diiodomethane, formamide and ethylene glycol. Blood compatibility of the PUs was evaluated by in vitro adhesion assay using 111In-radiolabeled platelet rich plasma and 125I-fibrinogen. The morphology of platelet adhesion was also observed by scanning electron microscopy (SEM). Results were compared with a biomedical-grade PU, Pellethane. Insertion of the carboxylic groups on the soft segments (S-alpha series), using thioglycolic acid (TGA), increases surface hydrophilicity, limits water uptake (5%, for an ion content of 3.6 wt%), and reduces platelet adhesion and fibrinogen adsorption on the PUs' surfaces. In contrast, the classical insertion onto the hard segment (H-alpha series), using dimethylolpropionate (DMPA) as chain extender, leads to high water uptake (18%, for an ion content of 3.6 wt%) and promotes platelet and fibrinogen adhesion. SEM analyses of the non-ionic PUs exhibited surfaces with adhered platelets which underwent morphological modification. Similarly, the H-alpha ionic PUs show adherent and activated platelets. On the contrary, no platelet morphology changes were observed on the S-alpha ionic surfaces. In conclusion, insertion of carboxyl groups on the soft segments of PUs reduces their thrombogenicity.

Synthesis and characterization of polyurethane and poly(ether urethane) nanocapsules using a new technique of interfacial polycondensation combined to spontaneous emulsification

Polyurethane polymers and poly(ether urethane) copolymers were chosen as drug carriers for alpha-tocopherol. This active ingredient is widely used as a strong antioxidant in many medical and cosmetic applications, but is rapidly degraded, because of its light, heat and oxygen sensitivity. Polyurethane and poly(ether urethane)-based nanocapsules were synthesized by interfacial reaction between two monomers. Interfacial polycondensation combined with spontaneous emulsification is a new technique for nanoparticles formation. Nanocapsules were characterized by studying particle size (150-500 nm), pH, yield of encapsulation and morphologies. Polyurethanes (PUR) were obtained from the condensation of diisocyanate (isophorone diisocyanate: IPDI) and polyol: 1,2-ethanediol (EG), 1,4-butanediol (BD), 1,6-hexanediol (HD). Poly(ether urethane) copolymers were obtained by replacing diols by polyethylene glycol oligomers (PEG) M(w) 200, 300, 400 and 600. Molecular weights of di- and polyols have a considerable influence on nanocapsules characteristics cited above. The increase of molecular weight of polyols tends to increase the mean size of nanocapsules from (232+/-3)nm using EG to (615+/-39)nm using PEG 600, and led to the apparition of a population of agglomerate particles. We also noted that the yield of encapsulation increases with the increase of polyol length (from 85.6 to 92.2% w/w). Microscopic observations confirmed particle size analysis, but cannot predict the membrane structure owing the small size of the particles.