Poly(ester-ether-ester) block copolymers, belonging to a class of biodegradable materials, were synthesized from poly(ethylene glycol) and epsilon-caprolactone by a simple ring-opening mechanism, which avoids the use of potentially toxic inorganic or organometallic initiators. The morphological and mechanical properties of such materials were investigated by gel-permeation chromatography, vapour pressure osmometry, proton magnetic resonance, infrared spectroscopy, differential scanning calorimetry, X-ray diffractometry and stress-strain tensile tests. The biocompatibility was investigated by cytotoxicity and hemocompatibility tests; the cytotoxicity was tested by the Neutral Red uptake assay, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay, the Kenacid Blue R-binding method, and by the cell proliferation test on polymer films; the hemocompatibility was tested by the contact activation both of the coagulation cascade (intrinsic pathway), by the plasma prekallikrein activation test, and of the thrombocytes, by measuring the release of platelet factor 4 and beta-thromboglobulin. The experimental results show that such a polymerization process permits high-molecular mass block copolymers with relatively good tensile and mechanical properties to be obtained. Their cyto- and hemo-compatibility makes them suitable for employment as biomaterials

Poly(vinyl alcohol) was used to make hydrogels containing various amounts of collagen. These "bioartificial materials", made of synthetic and biological polymers, were studied to investigate the effect of the presence of the collagen on the structural properties of the hydrogels. A comparison between thermal and morphological properties of collagencontaining hydrogels and hydrogels of pure poly(vinyl alcohol) was made.

Poly (L-lactide)-poly (oxyethylene)-poly (L-lactide) block copolymers obtained in bulk, by a ring opening mechanism, from poly(ethylene glycol)s (PEG)s and L-lactide (LA), at 120-140 degrees C, in the absence of added catalysts are described. By using PEGs with different molecular masses, 3000 and 35 000, respectively, and varying the initial molar ratio LA to PEG, two series of copolymers with different molecular masses, relative length of blocks and hydrophilicity were obtained. Physico-chemical characterization of the copolymers had been previously performed. The morphological characteristics of the copolymers were investigated by means of X-ray diffractometry, optical and scanning electron microscopy. The biological properties of the materials were determined by evaluating their cytotoxicity, cytocompatibility, hemocompatibility and degradability using different standard tests. The results obtained indicate that the block copolymers synthesized may be useful for biomedical applications, in particular as resorbable drug vehicles. The materials are brittle and their mechanical properties are not appropriate for implant devices

Abstract;: Blends of natural and synthetic polymers were studied for potential applications in the biomedical field. Collagen and hyaluronic acid were mixed in aqueous solution with poly(viny1 alcohol) and poly(acry1ic acid). The properties of the blends were studied by differential scanning calorimetry and dynamic mechanical thermal analysis. Some methods were also investigated to enhance the miscibility of the polymers in these blends.

The in vitro biocompatibility of fluorinated polyurethanes (FPUs), labelled as FPU 42, 52, 58, and 60, was evaluated by means of thrombogenicity, cytoxicity and cytocompatibility tests. Cardiothane(R) was taken as control material. The thrombogenicity was tested on thin material films by measuring the activation of prekallikrein (PKK) to kallikrein (KK). Level I cytoxicity tests of the bulk materials, i.e. Neutral Red (NR) uptake, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT), and Kenacid Blue (KB) assays, were performed to assess the influence of the polymer extracts on, respectively, lysosomes, mitochondria and cell proliferation. The cytocompatibility was evaluated, on thin membranes made by a spraying phase-inversion process, by measuring the area of the polymer surface covered by human umbilical vein endothelial cells (HUVEC) 1 week after seeding. The results indicate that all the polymers are not thrombogenic, and not cytotoxic. The FPUs that contain polycaprolactone glycol (PCLG) (FPU 52 and 60) instead of poly(tetramethylene ether) glycol (PTMEG) (FPU 42 and 58) as soft segment show the lowest thrombogenicity and the best cytocompatibility