Biocompatibility Of Polyurethanes Research Articles

The polydopamine‐assisted heparin anchor enhances the hydrophilicity, hemocompatibility, and biocompatibility of polyurethane

AbstractSurface heparinization is an effective solution to resolve low endothelialization, poor anticoagulation, and hemocompatibility of polyurethane (PU) used as materials of small‐diameter vascular grafts. Here, the effects of polydopamine (PDA) and poly (acrylic acid) (PAA) as crosslinking agents on the surface heparinization were explored. The PU membranes grafted with heparin (Hep) via dopamine (PU/PDA‐Hep) showed better hydrophilicity and stability, compared to heparinized PU membranes via acrylic acid (PU/PAA‐Hep). The results of X‐ray photoelectron spectroscopy demonstrated that heparin was successfully grafted onto the PU surface and the grafting efficiency was high when PDA as a cross‐linking agent. The grafted heparin aggregated and formed nanoparticles, and increased the surface roughness of PU membranes. The heparinized membranes demonstrated good anti‐adhesion of bovine serum albumin and fibrin protein. In addition, no activated platelets or educts on heparinized PU were found by platelet adhesion tests, implying that heparin‐immobilized surfaces had good hemocompatibility. Moreover, the in vitro cytocompatibility assessment showed that the PU/PDA‐Hep significantly improved the proliferation of L929 cells and was superior to PU/AA‐Hep. These results demonstrated that PDA‐assisted surface heparinization was an effective method to improve the anticoagulant and biocompatibility of PU small‐diameter vascular materials and could be extended to other implantable materials.

Hydrolytic stability and biocompatibility on smooth muscle cells of polyethylene glycol–polycaprolactone-based polyurethanes

Abstract

Production of Biodegradable Palm Oil-Based Polyurethane as Potential Biomaterial for Biomedical Applications.

Being biodegradable and biocompatible are crucial characteristics for biomaterial used for medical and biomedical applications. Vegetable oil-based polyols are known to contribute both the biodegradability and biocompatibility of polyurethanes; however, petrochemical-based polyols were often incorporated to improve the thermal and mechanical properties of polyurethane. In this work, palm oil-based polyester polyol (PPP) derived from epoxidized palm olein and glutaric acid was reacted with isophorone diisocyanate to produce an aliphatic polyurethane, without the incorporation of any commercial petrochemical-based polyol. The effects of water content and isocyanate index were investigated. The polyurethanes produced consisted of > 90% porosity with interconnected micropores and macropores (37–1700 µm) and PU 1.0 possessed tensile strength and compression stress of 111 kPa and 64 kPa. The polyurethanes with comparable thermal stability, yet susceptible to enzymatic degradation with 7–59% of mass loss after 4 weeks of treatment. The polyurethanes demonstrated superior water uptake (up to 450%) and did not induce significant changes in pH of the medium. The chemical changes of the polyurethanes after enzymatic degradation were evaluated by FTIR and TGA analyses. The polyurethanes showed cell viability of 53.43% and 80.37% after 1 and 10 day(s) of cytotoxicity test; and cell adhesion and proliferation in cell adhesion test. The polyurethanes produced demonstrated its potential as biomaterial for soft tissue engineering applications.

Adjustable Polyurethane Foam as Filling Material for a Novel Spondyloplasty: Biomechanics and Biocompatibility.

To investigate the biomechanics and biocompatibility of polyurethane (PU) foam with adjustable stiffness as a filling material for a novel spondyloplasty that is designed to reduce the risk of postoperative adjacent level fractures. Sixty individual porcine lumbar vertebrae were randomly split into 4 groups: A, B, C, and D. Group A served as unmodified vertebral body controls. Groups B, C, and D consisted of hollowed vertebral bodies. Vertebrae of groups C and D were filled with adjustable PU foams of different stiffness. The compressive strength and stiffness of vertebrae from groups A-D were recorded and analyzed. 3T3 mouse fibroblasts were cultured with preformed PU foams for 4 days to test biocompatibility. The strength and stiffness of the hollowed groups were lower than in group A. However, the differences were not statistically significant between group A and group C (P > 0.05), and were obviously different between group A and group B or group D (P < 0.01 and <0.05, respectively). Moreover, the strength and stiffness after filling foams in group C or group D were significantly greater than in group B (P < 0.01 and <0.05, respectively). Live/dead staining of 3T3 cells confirmed the biocompatibility of the PU foam. The new PU foam shows adaptability regarding its stiffness and excellent cytocompatibility invitro. The results support the clinical translation of the new PU foams as augmentation material in the development of a novel spondyloplasty.

114: The incorporation of human recombinant tropoelastin improves the biocompatibility of high or low porosity polyurethane

Polyurethanes (PU) are synthetic polymer and have been widely used in medical devices and artificial organs for tissue repair. High and low porous polymer scaffolds containing recombinant human tropoelastin (TE) and PU were generated by electrospinning technique; these scaffolds have favourable mechanical and biological properties used as implantable applications. This study was to evaluate the acute and chronic inflammatory response to implantation of low and high porosity PU scaffolds with/without TE in mouse model. The back of each C57B/L6 mouse (n = 32) was subcutaneously implanted with control PU, low porosity PU/tropoelastin (PU/TE) and high porosity PU/tropoelastin (HP PU/TE) implants. Mice (n = 8) were euthanized and harvested the tissue samples at 1 day, 1 week, 2 weeks and 4 weeks. Histopathology and immunohistochemistry were performed to assess inflammatory cell infiltration, collagen deposition and granulation formation of each sample. Compared to control PU, fewer neutrophils were found on PU/TE and HP PU/TE implant surface, associated with lower expression of GM-CSF at 1 day following implantation. After 1 weeks, compared the surrounding granulation tissue formation from PU, both HP PU/TE and PU/TE have been found that thinner capsule thickness with less total infiltrating cells and proliferating cells PCNA, fewer macrophage/FBGCs F4/80, less neovascularization VWF, down-regulation level of MMP-2, MMP-9 and cytokines, including GM-CSF, IL-6, IL-10. Compared the tissue ingrowth of low porosity PU/TE implant, high porous HP PU/TE scaffolds demonstrated a larger number of total infiltrating cells inside the implant, associated with larger collagen deposition, greater proliferation rate PCNA, higher level of cytokines GM-CSF, IL-10 and MMP-2 after 2 weeks. Overall results suggested that firstly, the incorporation of TE into either high or low porosity PU scaffold could improves in the biocompatibility of PU alone, uniquely measured here as a reduced foreign body inflammatory response and better wound healing response at whole implant sites. Secondary, high porosity PU/TE enhanced and accelerated the active cells proliferation and infiltration into the scaffolds compared to low porosity scaffold.

Hemocompatibility evaluation of polyurethane film with surface‐grafted poly(ethylene glycol) and carboxymethyl‐chitosan

AbstractTo improve the hemocompatibility and biocompatibility of polyurethanes (PUs), PU surface was firstly modified by poly(ethylene glycol) PEG through acryloyl chloride and subsequently grafted on carboxymethyl‐chitosan (CMCS). Attenuated total reflection Fourier transform infrared spectroscopy and X‐ray photoelectron spectroscopy analysis confirmed that carboxyl‐chitosan was grafted onto PUs surface. The surface properties of unmodified and modified PU films were determined and compared by water contact angle assessment. After PEG and CMCS grafting, the surface energy of the PU film was increased. Furthermore, the hemocompatibility of the modified PU films was systematically evaluated by bovine serum albumin (BSA) adsorption, the dynamic blood clotting test, the platelet adhesion test, and the hemolytic test. It appears that BSA adsorption and platelet adhesion were significantly curtailed for the modified PU films. Therefore, the obtained results showed the modified PU film has better hemocompatibility. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

LARGELY IMPROVED BLOOD COMPATIBILITY OF POLYURETHANE BY BLENDING WITH FLUORINATED PHOSPHATIDYLCHOLINE POLYURETHANE

The improvement of biocompatibility of polyurethanes was investigated. The results demonstrate that the blood compatibility of polyurethanes can be further improved by just simply mixing with the fluorinated phosphatidylcholine poly(carbonate urethane)s (FPCPCUs). The solution blending was done by mixing poly(ether urethane) (PEU) with FPCPCU in different compositions. An increased blood compatibility of the blend films was observed with the increase of FPCPCU content, and when FPCPCU content reached to 40 wt% (40FPCPCU film), 6 times and 23 times decrease of platelet adhesion number have been achieved, compared with that of FPCPCU and PEU, respectively. More interestingly, the blend films showed even better blood compatibility than that of FPCPCU. DSC, AFM and XPS were used to characterize the miscibility and surface structure of the blends film. The largely improved blood compatibility was rationalized based on the combined effect of phase separation between PEU and FPCPCU and the formation of surface nanostructures induced by segregation of FPCPCU at the surface.

Influence of Catalyst Type on Biocompatibility of Polyurethanes

Segmented polyurethanes (PUR) based on poly(ε-caprolactone)diol (PCL) as soft segments and cycloaliphatic diisocyanate were obtained. Two different types of catalysts were used for synthesis: dibutyltin dilaurate (DBTDL) and iron (III) acetylacetonate Fe(acac)3. Structure, thermal analysis, water absorption of obtained polyurethanes were studied. Polyurethanes catalyzed by Fe(acac)3 have lower glass transition temperature (Tg2) and melting temperature (Tm2) of hard domains in comparison with polyurethanes synthesized with DBTDL. Amount of absorbed water is in the range of 1,0-2,0% and is higher for PUR catalyzed by DBTDL. SEM observations show that type of catalyst used in synthesis affect structure of polyurethanes. Biological test XTT was done in order to determine influence of various metallic compounds used as catalyst on viability of human bone cell culture. The XTT results indicate no influence on viability of human osteoblasts cultured on the obtained PUR.

Effects of polydimethylsiloxane grafting on the calcification, physical properties, and biocompatibility of polyurethane in a heart valve

AbstractSegmented polyurethane (PU) has proven to be the best biomaterial for artificial heart valves, but the calcification of polyurethane surfaces causes serious problems in long‐term implants. This work was undertaken to evaluate the effects of polydimethylsiloxane (PDMS) grafting on the calcification, biocompatibility, and blood compatibility of polyurethane. A grafted polyurethane film was compared with virgin polyurethane surfaces. Physical properties of the samples were examined using different techniques. The hydrophobicity of the polyurethane films increased as a result of silicone modification. The effects of surface modification of polyurethane films on their calcification and fibroblast cell (L 929) and platelet behavior were evaluated in vitro. Fourier transform infrared spectroscopy indicated the direct involvement of the polyether soft segments of the polymer in the calcification process. Scanning electron microscopy of films indicated that grafting of silicone rubber to the surface of polyurethane successfully prevented the calcification process. The morphology of fibroblast cells that adhered to the PU films and modified films was similar to that of controls and showed the same proliferation. On the other hand, grafting PDMS onto PU did not affect the amount of platelets that adhered to the polyurethane surfaces. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 758–766, 2005

Biocompatibility of Poly(carbonate urethane)s with Various Degrees of Nanophase Separation

Nanophase separation has been suggested to influence the biological performance of polyurethane. In a previous work, six different 4,4'-diphenylmethane diisocyanate (MDI)-based poly(carbonate urethane)s (PCUs) that exhibited various degrees of nanophase separation were synthesized and characterized. In the present work, these PCUs were used as a model system to study the effect of nanometric structures on the biocompatibility of polyurethane. Human blood platelet activation, monocyte activation, protein adsorption, and bacterial adhesion on PCU were investigated in vitro. It was found that human blood platelets as well as monocytes were less activated on the PCU surfaces with a greater degree of nanophase separation in general. This phenomenon was closely associated with the lower ratio of human fibrinogen/albumin competitively adsorbed on these surfaces. Bacterial adhesion was also inhibited in some nanophase-separated PCUs. [diagram in text].

Biocompatibility of MPC: in vivo evaluation for clinical application

Biocompatibility is important to assure a mild body reaction to an implanted device and its long-term stability and functionality. In diabetes research, subcutaneously implanted glucose monitoring systems need biocompatible surfaces for long-term application. The biocompatibility of poly(2-methacryloyloxyethyl phosphorylcholine-co-n-butyl methacrylate) (MPC), a material similar to the phospholipid layer of a cell membrane, was compared in vivo with the biocompatibility of polyurethane (PU), polyvinyl alcohol (PVA), and cuprophane (CUP). Needle-type glucose sensors and hollow-fiber probes used for microdialysis were coated with these four different biomaterials and implanted subcutaneously in 18 rats and 7 healthy volunteers. At set intervals, the implants and, in the case of the rats, also the surrounding tissue were removed and characterized by light and electron microscopy. MPC-coated sensors and hollow-fiber probes showed smooth and thin deposits in flat layers, whereas the surface deposits on PU- and PVA-coated sensors and those on CUP hollow-fiber probes appeared as rough, irregular, and dense attachments of aggregated cells and protein. This study confirmed results from earlier in vitro tests by showing the biocompatibility and reliability of MPC. Even though the amount of protein and cells attached to the MPC surface was not as low as expected from in vitro experiments, the biocompatibility and long-term stability of the implanted devices were superior to those of PU, PVA, and CUP.

Antimicrobial activity and biocompatibility of polyurethane and silicone catheters containing low concentrations of Silver: A new perspective in prevention of polymer-associated foreign-body-infections

In modern medicine, infection is one of the most serious complications of implanted plastic devices. The host is not able to overcome this special type of opportunistic infection despite having a normal immune response and a low virulence of most of the bacteria involved. Antimicrobial therapy alone generally cannot cure the infection and the removal of catheters often remains the only choice of therapy. Bacterial adhesion to the polymer surface of the catheter, be it luminal or external, is an important step in the pathogenesis of catheter-associated infections. In this report, we describe new approaches to the prevention of infections by impregnation of polyurethane and silicone with silver by two different methods. The antimicrobial activity of these silver-impregnated catheters is more than 10 fold higher for coagulase-negative staphylococci (CNS) compared to catheters without silver. Similar results are obtained with other microbial organisms like Staphylococcus aureus, Enterococcus faecalis, Escbericbia coli, Pseudomonas aeruginosa and Candida albicans. The new polymers show no cytotoxic or thrombogenic side effects in vitro.

Surface structure and biocompatibility of polyurethanes

Two series of polyether polyurethanes, chain extended by ethylene glycol, have been synthesised with rigid exclusion of moisture to avoid side reactions. The polyether molecular weight was varied in each series. The polymers, which have been well characterised, are used to correlate surface properties and biocompatibility. The polyethylene glycol materials showed no significant surface segregation when examined by XPS. The polytetramethylene glycol polymers showed marked surface segregation of soft block. SIMS analysis showed that, even with surface segregation of soft block, some hard block was present at the outermost surface. Contact angle data confirmed that variations in polymer surface structure, with an increase in soft block molecular weight, were also present when the membrane was in an aqueous environment. Biocompatibility tests showed that there were no detectable differences between the polytetramethylene materials, though the surface compositions varied. The polytetramethylene polyurethanes were similar to Biomer in biocompatibility.

In vivo biocompatibility of aliphatic segmented polyurethane in rabbit

An aliphatic segmented polyurethane with soft to hard segment ratio 3 was synthesised using hexamethylene diisocyanate, polypropylene glycol 400 and 1,4-butane diol.A stainless steel cage implant system has been used to study the in vivo biocompatibility of this polyurethane. United States Pharmacopoeia negative control polyethylene was used for the comparison. Three cages, one with polyurethane another with United States Pharmacopoeia polyethylene and the third control empty cage were implanted subcutaneously in the dorsal aspect of rabbits. The inflammatory exudate surrounding the material was aspirated from the cages on 4, 7, 14 and 21 days after implantation. The total protein content in the exudate aspirated from all the 3 cages was significantly higher at 7 days than in the reported normal rabbit serum of New Zealand white rabbit but equal to that of our rabbit colony. The albumin concentration was lower in the initial period but increased at 21 days post implantation period in all the cages. Concentration of α1, α2 and γ-globulin also decreased in all cages at 21 days. Neutrophils were predominant in all the exudates aspirated from polyurethane, polyethylene and empty control cages during whole implantation period. This is attributed to the profound effect of the cages on the surrounding vasculature. Macrophage was found to be seen during acute phase of inflammation due to the migration of macrophage along with neutrophil towards the inflammatory lesion. The percentage of neutrophils showed a faster decline in the cage containing polyethylene at 21 days. The extra cellular alkaline phosphatase activity, though higher in exudate from cages containing polyurethane at 14 days post implantation, was same in all 3 cages at 21 days. Leucine amino peptidase activity was found to be decreased at 21 days of post implantation time though the empty control cage exhibited an increase at 14 days post implantation. The inflammatory response at 21 days was similar in polyurethane and the control polyethylene.