Antibiotic loaded microspheres as antimicrobial delivery systems for medical applications.

In this paper, we present the preparation and antibiotic loading of polymeric microspheres, composed of copolymers derived from fatty acid/amino acid components, as new polymeric platforms for antibiotic delivery systems. New polymeric materials were used to prepare microspheres with and without immobilized model antibiotics (streptomycin, chloramphenicol and amphotericin B) by a W/O/W double-emulsion/solvent evaporation method, in which chloroform and poly(vinyl alcohol) are used as the solvent and emulsifier, respectively. The antimicrobial activity of the microspheres was tested against Gram-positive S. aureus, Gram-negative E. coli bacteria, and C. albicans, as a representative of a fungus. The new polymeric microspheres are particularly effective carriers for streptomycin, exhibiting antibacterial activity against all tested microorganisms.

New injectable elastomeric biomaterials for hernia repair and their biocompatibility.

Complications associated with implantation of polymeric hernia meshes remain a difficult surgical challenge. We report here on our work, developing for the first time, an injectable viscous material that can be converted to a solid and elastic implant in vivo, thus successfully closing herniated tissue. In this study, long-chain fatty acids were used for the preparation of telechelic macromonomers end-capped with methacrylic functionalities to provide UV curable systems possessing high biocompatibility, good mechanical strength and flexibility. Two different systems, comprising urethane and ester bonds, were synthesized from non-toxic raw materials and then subjected to UV curing after injection of viscous material into the cavity at the abdominal wall during hernioplasty in a rabbit hernia model. No additional fixation or sutures were required. The control group of animals was treated with commercially available polypropylene hernia mesh. The observation period lasted for 28 days. We show here that artificially fabricated defect was healed and no reherniation was observed in the case of the fatty acid derived materials. Importantly, the number of inflammatory cells found in the surrounding tissue was comparable to these found around the standard polypropylene mesh. No inflammatory cells were detected in connective tissues and no sign of necrosis has been observed. Collectively, our results demonstrated that new injectable and photocurable systems can be used for minimally invasive surgical protocols in repair of small hernia defects.

Influence of ceria nanoparticles on chemical structure and properties of segmented polyesters.

In this work, we present new nanocomposite materials derived from segmented copolyesters, comprising ethylene terephthalate (PET) segments and dimerized linoleic acid (DLA), and nanometric cerium oxide particles (CeO2). Nanoparticles were incorporated in situ during polycondensation in various concentrations, from 0.1 up to 0.6 wt.%. It was found that preparation of nanocomposites in situ, during polycondensation, had no significant influence on changes in segmental composition as determined from (1)H and (13)C, as well as 2D NMR. Thermal analysis and calculated degree of crystallinity showed that increasing concentration of ceria nanoparticles lead to an increase in mass content of PET crystallites in hard segments. The XRD investigations also showed an increased intensity of characteristic signals with increasing ceria concentration. Simultaneously, the incorporation of CeO2 led to an increase in tensile strength and elongation at break, indicating a reinforcing and plasticizing effect of ceria nanoparticles. However, the modulus at 10% strain decreased with increasing amount of nanoparticles. The in vitro culture of human cardiac progenitor cells (hCPCs) on the new materials indicated a homogenous cell displacement across the samples after 5 days with no signs of cytotoxicity, indicating good biocompatibility in vitro of CeO2-based nanocomposites and a potential for biomedical applications.

Preparation and bioactivity of novel multiblock thermoplastic elastomer/tricalcium phosphate composites.

There is a recognized need for improved treatment of osteoarthritis of the finger joints disease. Joint fusions are commonly used for treating the pain and potential deformity of arthritis. At severe deformity, artificial joint replacement is required. The most widely used are space-filler type joints made of high performance silicone rubber. One of the problems that occurs with these artificial replacements is that they can fail, because silicone elastomer used for their fabrication is relatively weak material and show to break apart and fragment. We have recently developed novel poly(aliphatic/aromatic-ester) (PED) material of sufficient mechanical properties and excellent flexibility. To enhance the bioactivity of these polymers (PED) and bone-bonding properties, PED/beta-TCP composites were prepared. The ceramic particles were homogeneously distributed during conventional blending and showed good adhesion to the polymer matrix. The thermal characteristics and mechanical properties of the composites were investigated as a function of beta-TCP content. The Youngs modulus and the yield strength of the composites increased with the increase in beta-TCP volume while the tensile strength and fracture strain decreased. In vitro investigations demonstrated an increase in cytocompatibility with increasing amount of beta-TCP up to 20 vol%.

[Biocompatibility assessment of aqueous extracts from new multiblock poly(ester-ester) copolymer]. / Badania biologiczne wyciagów wodnych z nowego multiblokowego poli(estro-estro) kopolimeru.

In the Technical University of Szczecin, Department of Chemical Fibres and Physical Chemistry of Polymer there has been synthesised a new polymer based on butylene terephthalate--PBT and dimerized fatty acid--DFA. Five different polymers varying in mechanical properties depending on hard segments--PBT and soft segments--DFA composition were obtained. Assessment of biocompatibility of the new materials was conducted according to FDP. Prepared water extracts from polymers were applicated intravenously to mouse and intra-abdominaly to mice and guinea pigs. All animals survived spell of the experiment and no signs of physical degradation were noticed. Kidney, liver, spleen, heart and peritoneum specimens was taken and evaluated microscopically. There was no signs of toxic action of the extracts. Based on principles in FDP and the data from animal studies it is applicable that evaluated materials have no increased toxicity.

[Assessment of tissue responsiveness after implantation of a new block copolymer into rat tissue]. / Badanie odpowiedzi tkankowej po wszczepieniu nowego kopoliestru blokowego do tkanek szczura.

The report describes tissue response an implantation of new block copolymer and compares with tissue response after presently used in medicine polymer implants. Implants shaped as 15 x 3 mm cylinders were placed subcutaneously on the abdomen and into muscles of both tight of Wistar rats. After 3, 7 and 14 days was taken tissue specimens with implants and kidneys to gross and light microscope examination. During the experiment there was not toxic signs considering rat's appearance and behaviour. Microscopic examination shows no difference between tissue response to presently in medicine used implants and new polymers.

The influence of new polyester block copolymer on morphology of hepatocytes of rats liver.

The liver is a complex organ with metabolic, excretory, and defence functions, so the effect of toxic polymers is often find in disorganisation of hepatic structure and may induce cell damage. In this study it is estimated the influence of recently synthesised multiblock copolymers based on poly/butylene terepthalate) and a dimerized fatty acid. The films of polymers were implanted intra-abdominally in 45 rats of Wistar breed covering the right lobe of liver. The specimens of liver were collected in 1, 3 and 6 day of experiment in order to be evaluated under microscope. The morphology of lobules, size and shape of hepatocytes, size and shape of nuclei's of hepatocytes, any infiltration of plasma cell were taken into account during examination. There have been no difference in morphology between specimens of liver from rats with implanted polymer and control group which could implicate their toxicity.