Polycarbonate Polyurethane Research Articles

Perioperative Outcomes: Polycarbonate Polyurethane Artificial Blood Vessel Versus Polyester Artificial Blood Vessel.

The objective of this study was to compare the perioperative performance of the novel large-diameter composite polycarbonate polyurethane graft and the polyester graft. In this study, we retrospectively analyzed 14 patients with thoracic aortic prosthesis replacement from 2016 to 2021. The preoperative, intraoperative, and postoperative data of the 2 groups were assessed in detail. We defined the patients with polyester grafts as the control group and the patients with polycarbonate polyurethane grafts as the experimental group. The total operation time of the experimental group was significantly shorter than that of the control group, which were 159.29±38.13 minutes and 252.57±64.40 minutes, respectively (p<0.001). The length of time from aortic opening to the end of operation in the experimental group was significantly shorter than that in the control group, which were 70.43±8.08 minutes and 124.71±37.59 minutes, respectively (p<0.001). The mean total drainage of pleural fluid was lower in the experimental group than in the control group (383.43±139.68 mL vs. 828.00±457.27 mL; p<0.05). The mean postoperative in-hospital time was shorter in the experimental group than in the control group (6.71±0.75 days vs. 9.43±2.82 days; p<0.05). This study provides preliminary evidence that the novel artificial blood vessel has good mechanical properties, histocompatibility, hemocompatibility, and anti-seepage function in the human body. A multicenter randomized controlled trial is needed for further validation. The novel hybrid polycarbonate polyurethane (PCU)/polyester three-layered large-diameter artificial blood vessel simulates the internal, middle, and external layers of the human blood vessels. The inner and outer layer are made of PCU, and the middle reinforcing layer is woven by polyester. Because of the three-layered structure, this artificial blood vessel has excellent anti-seepage and anti-infection functions. the inner and outer layers of the blood vessel made of PCU let this artificial blood vessel has excellent blood compatibility, outstanding biocompatibility, high endothelialization rate, and 100% patency. By comparing the perioperative outcomes with the polyester artificial blood vessel, we find it has good mechanical properties, histocompatibility, hemocompatibility and anti-seepage function in the human body.

Hydrogen bond interaction and mechanical property of polycarbonate polyurethane solid electrolyte

The previously unconsidered hydrogen bond (H-bond) networks in polyurethane solid polymer electrolytes (PUSPE) were studied by density functional theory. We further understood the H-bond interaction in PU, judged H-bond path, and quantified H-bond energy through atomic in molecular theory topological analysis. The frequency of the theoretical model is compared with the experimental value by Fourier transform infrared spectroscopy. The effect of H-bond on mechanical property of four kinds of polycarbonate (PCDL) PUSPE with different hard segments (diphenylmethane diisocyanate MDI/4,4′-dicycloethyl methane diisocyanate HMDI/toluene diisocyanate TDI/isoflurone diisocyanate IPDI) were discussed by double-chains models. The higher tensile strength and lower elongation at break of MDI-PUSPE result from the higher H-bond interaction strength between hard segments. The H-bond interaction between TFSI- and hard segment is studied, and it is determined by kinetic analysis that it reduces the migration energy barrier. These findings provide theoretical guidance for designing PU electrolytes in the future.

Chain Extender-induced Hydrogen Bonding Organization Determines the Morphology and Properties of Thermoplastic Polycarbonate Polyurethane

Chain Extender-induced Hydrogen Bonding Organization Determines the Morphology and Properties of Thermoplastic Polycarbonate Polyurethane

Serum- and xeno-free culture of human umbilical cord perivascular cells for pediatric heart valve tissue engineering

BackgroundConstructs currently used to repair or replace congenitally diseased pediatric heart valves lack a viable cell population capable of functional adaptation in situ, necessitating repeated surgical intervention. Heart valve tissue engineering (HVTE) can address these limitations by producing functional living tissue in vitro that holds the potential for somatic growth and remodelling upon implantation. However, clinical translation of HVTE strategies requires an appropriate source of autologous cells that can be non-invasively harvested from mesenchymal stem cell (MSC)-rich tissues and cultured under serum- and xeno-free conditions. To this end, we evaluated human umbilical cord perivascular cells (hUCPVCs) as a promising cell source for in vitro production of engineered heart valve tissue.MethodsThe proliferative, clonogenic, multilineage differentiation, and extracellular matrix (ECM) synthesis capacities of hUCPVCs were evaluated in a commercial serum- and xeno-free culture medium (StemMACS™) on tissue culture polystyrene and benchmarked to adult bone marrow-derived MSCs (BMMSCs). Additionally, the ECM synthesis potential of hUCPVCs was evaluated when cultured on polycarbonate polyurethane anisotropic electrospun scaffolds, a representative biomaterial for in vitro HVTE.ResultshUCPVCs had greater proliferative and clonogenic potential than BMMSCs in StemMACS™ (p < 0.05), without differentiation to osteogenic and adipogenic phenotypes associated with valve pathology. Furthermore, hUCPVCs cultured with StemMACS™ on tissue culture plastic for 14 days synthesized significantly more total collagen, elastin, and sulphated glycosaminoglycans (p < 0.05), the ECM constituents of the native valve, than BMMSCs. Finally, hUCPVCs retained their ECM synthesizing capacity after 14 and 21 days in culture on anisotropic electrospun scaffolds.ConclusionOverall, our findings establish an in vitro culture platform that uses hUCPVCs as a readily-available and non-invasively sourced autologous cell population and a commercial serum- and xeno-free culture medium to increase the translational potential of future pediatric HVTE strategies.Graphical This study evaluated the proliferative, differentiation and extracellular matrix (ECM) synthesis capacities of human umbilical cord perivascular cells (hUCPVCs) when cultured in serum- and xeno-free media (SFM) against conventionally used bone marrow-derived MSCs (BMMSCs) and serum-containing media (SCM). Our findings support the use of hUCPVCs and SFM for in vitro heart valve tissue engineering (HVTE) of autologous pediatric valve tissue. Figure created with BioRender.com.

Effects of simulated body fluid on the mechanical properties of polycarbonate polyurethane produced via material jetting

A possible tissue substitute material, namely a thermoplastic polycarbonate polyurethane with two different hard-to-soft segment ratios, was produced via material jetting. Since application temperature and media can significantly alter the properties of polymeric materials, it is necessary to understand the impact of both. Therefore, tensile and high-cycle fatigue tests were performed without media as well as immersed in a simulated body fluid. The absorption of phosphate-buffered saline (PBS) led to a decrease in stiffness and tensile strength with a simultaneous increase in elongation at break. For the material with less hard segments, an elevated temperature resulted in a similar effect. More hard segments increase tensile strength and elongation at break. Furthermore, the fatigue behaviour deteriorates significantly with increasing fluid uptake. The fatigue strength of fully saturated specimens decreased by about 20% compared to untreated specimens. An absorption of approx. 20% of the PBS absorption maximum already showed a similar decrease.

Sulfur-Mediated Polycarbonate Polyurethane for Potential Application of Blood-Contacting Materials.

In this study, a sulfur-mediated polycarbonate polyurethane (PCU-SS) is developed by mimicking the catalyzing ability of glutathione peroxidase (GPx) on nitric oxide (NO) in the human body. The PCU-SS is endowed with the capability to produce NO based on disulfide bonds, which could strongly improve the biocompatibility of the materials. The characterization results indicate that PCU-SS could not only decrease the adhesion of platelets but also enhance the capability of anti-thrombus. Moreover, it is shown that PCU-SS has a good compatibility with endothelial cells (ECs), while has a marked inhibition capacity of the proliferation of smooth muscle cells (SMCs) and macrophages (MA). Meanwhile, the result of animal implantation experiments further demonstrates the good abilities of PCU-SS on anti-inflammation, anti-thrombus, and anti-hyperplasia. Our results offer a novel strategy for the modification of blood-contacting materials based on disulfide bonds. It is expected that the PCU-SS could shed new light on biocompatibility improvement of cardiovascular stents.

Analysis of oxidative degradation and calcification behavior of a silicone polycarbonate polyurethane-polydimethylsiloxane material.

The biocompatibility and chemical stability of implantable devices are crucial for their long-term success. CarboSil® is a silicon polycarbonate polyurethane copolymer with good biocompatibility and biostability properties. Here, we explored the possibility to improve these characteristics by introducing 30% of extra-chain cross-linkable poly(dimethyl siloxane) (PDMS). Patches made of CarboSil and CarboSil-30% PDMS were manufactured by spray, phase-inversion technique and subjected to a heating-pressure treatment. Both materials showed good biocompatibility, either in viability and proliferation of cell-based experiments both with mouse fibroblasts and subcutaneous implant in rats. Fourier-transform infrared spectroscopy showed a significant decrease in soft segment loss in CarboSil-30% PDMS samples with respect to CarboSil in in vitro accelerated oxidative treatments with CoCl2 and 20% H2 O2 at 37°C up to 36 days. Same results were observed in subcutaneous implants up to 90 days. Field-emission scanning electron microscopy on samples exposed to calcification solutions during 80 days highlighted the presence of a homogeneous distribution of calcium deposition over the entire surface of CarboSil samples, while no calcium deposits were observed in CarboSil-30% PDMS samples. Patches subjected to subcutaneous experiments showed no sign of calcification after 90 days, irrespectively of their composition. Thanks to the improved characteristics in terms of degradation and calcification the modified materials described in this work hold great promise for their use in the manufacture of cardiovascular devices.

Synthesis and properties of high performance thermoplastic polycarbonate polyurethane elastomers through a non-isocyanate route.

Thermoplastic polycarbonate polyurethane elastomers (TPCUEs) are synthesized through a solvent-free non-isocyanate melt polycondensation route. The route starts with the synthesis of 1,6-bis(hydroxyethyloxycarbonylamino)hexane (BHCH) from ethylene carbonate and 1,6-hexanediamine, and then the TPCUEs are prepared by the melt polycondensation of BHCH and polycarbonate diols (PCDLs). The TPCUEs are characterized by GPC, FT-IR, 1H NMR, XRD, AFM, DSC, TGA and tensile testing. The TPCUEs prepared have linear structures and high molecular weights, with Mn over 3.0 × 104 g mol-1. And these TPCUEs exhibit excellent thermal and mechanical properties, with T g ranging from -18 to -1 °C, T m ranging from 93 to 122 °C, T d,5% over 240 °C, tensile strength between 28.1-47.3 Mpa, elongation at break above 1000%, Young's modulus between 13.8-32.7 Mpa and resilience at 200% fixed-length between 70-90%, which makes them a promising alternative to products synthesized through the isocyanate route. In addition, the effects of the hard segment contents and the molecular weights of soft segment on the properties of TPCUEs are researched.

Surface-Catalyzed Nitric Oxide Release via a Metal Organic Framework Enhances Antibacterial Surface Effects.

It has been previously demonstrated that metal nanoparticles embedded into polymeric materials doped with nitric oxide (NO) donor compounds can accelerate the release rate of NO for therapeutic applications. Despite the advantages of elevated NO surface flux for eradicating opportunistic bacteria in the initial hours of application, metal nanoparticles can often trigger a secondary biocidal effect through leaching that can lead to unfavorable cytotoxic responses from host cells. Alternatively, copper-based metal organic frameworks (MOFs) have been shown to stabilize Cu2+/1+ via coordination while demonstrating longer-term catalytic performance compared to their salt counterparts. Herein, the practical application of MOFs in NO-releasing polymeric substrates with an embedded NO donor compound was investigated for the first time. By developing composite thermoplastic silicon polycarbonate polyurethane (TSPCU) scaffolds, the catalytic effects achievable via intrapolymeric interactions between an MOF and NO donor compound were investigated using the water-stable copper-based MOF H3[(Cu4Cl)3(BTTri)8-(H2O)12]·72H2O (CuBTTri) and the NO donor S-nitroso-N-acetyl-penicillamine (SNAP). By creating a multifunctional triple-layered composite scaffold with CuBTTri and SNAP, the surface flux of NO from catalyzed SNAP decomposition was found tunable based on the variable weight percent CuBTTri incorporation. The tunable NO surface fluxes were found to elicit different cytotoxic responses in human cell lines, enabling application-specific tailoring. Challenging the TSPCU-NO-MOF composites against 24 h bacterial growth models, the enhanced NO release was found to elicit over 99% reduction in adhered and over 95% reduction in planktonic methicillin-resistant Staphylococcus aureus, with similar results observed for Escherichia coli. These results indicate that the combination of embedded MOFs and NO donors can be used as a highly efficacious tool for the early prevention of biofilm formation on medical devices.

Ultrathin fibre coatings on nanofibrous nonwovens by plasma enhanced chemical vapor deposition

Abstract For the generation of tailor-made polymer coatings on nanofibrous nonwovens plasma enhanced chemical vapor (PECVD) is a promising process, even for complex geometries. The plasma coatings can greatly improve their suitability for biomedical applications by optimising biocompatibility to the local needs, especially for cardiovascular disease treatments. Therein, wound healing and endothelialisation are important steps which are connected by a complex interaction. The monomers allylamine and hexamethyldisiloxane, as well as different process conditions were studied for the coating of nanofibrous thermoplastic silicone polycarbonate polyurethane (TSPCU) nonwovens. Aim of this study was to investigate the feasibility of plasma polymer coating under preservation of the nanofibrous morphological structure. Beside characterization of the nonwoven, biological evaluation with endothelial and fibroblast cells was performed. The prepared nonwoven samples support the feasibility of plasma coating under preservation of the nanofibrous structure. Also, different effects of the surfaces in contact with fibroblasts and endothelial cells could be observed.

A biocompatible pressure sensor based on a 3D-printed scaffold functionalized with PEDOT:PSS for biomedical applications

Personalized health-care monitoring, such as human motion and gait, can provide valuable information useful for prevention and diagnosis of a variety of diseases and also in patients rehabilitation. By employing suitable biocompatible materials that possess tunable compression properties related to 3D structure and able to convert the strain stimuli into a detectable signal, pressure sensors for human motion monitoring can be developed. In this study, our purpose is to obtain a conductive and biocompatible scaffold able to transform the mechanical deformations caused by an applied pressure to an electrical resistance variations. In particular, the effect of a conductive biocompatible functionalization with PEDOT:PSS polymer on thermoplastic silicone polycarbonate polyurethane (CarboSil) scaffold presenting five different structures have been studied by mechanical and electrical tests. The scaffold stiffness depends on structures features but it is not affected by the PEDOT:PSS coating. The electrical tests show a linear response on a wide range of pressure loads with all the tested polymeric scaffolds. Two scaffolds show the higher conductivity respect to other samples. Therefore, the scaffold structure network influences the electrical sensor response. The possibility to exploit the 3D printing tecnology with CarboSil paves the way to a new class of customizable, easy to manufacture and biocompatible integrated devices for medical applications. • Monitoring human motion to provide information for bone healing fractures. • 3D printing technology to create different and customizable polyurethane scaffolds. • PEDOT:PSS functionalization to obtain a conductive and biocompatible scaffold. • Pressure sensor to convert the strain stimuli into a detectable signal.

The novel hybrid polycarbonate polyurethane / polyester three-layered large-diameter artificial blood vessel.

The most common materials of artificial blood vessels are polyethylene terephthalate and polytetrafluoroethylene. But polycarbonate polyurethane (PCU) is an ideal material for vascular prostheses because of their excellent characteristics. As far as we know, our artificial blood vessel is the first type of hybrid PCU/polyester three-layered large-diameter artificial blood vessel in the world. The purpose of this preclinical animal experiment is to evaluate the hemocompatibility, histocompatibility, effectiveness, and safety of the three-layered large-diameter artificial blood vessel in sheep. The artificial blood vessels took place of the initial segments of the sheep's thoracic aorta by end-to-end anastomosis. All of the 14 sheep are male, their average body weight (BW) was 30.57 ± 3.95 kg. All 14 artificial blood vessels successfully replaced the thoracic aortas. 5 sheep did not survive to the end of the experiment, while the remaining 9 sheep did. After the surgery, the blood biochemical and blood routine indicators fluctuate slightly within the normal range. The angiography showed that the implanted artificial blood vessels were unobstructed without obvious stenosis or expansion. 24 weeks after surgery, the lumen surfaces of the artificial blood vessels were covered by endothelia in different degrees, and the average endothelialization rate was 69.44% (range: 20% to 100%). This artificial blood vessel is the first to use PCU in large-diameter artificial vascular grafts. It has excellent blood compatibility, wonderful biocompatibility, high endothelialization rate, and 100% patency.

A 3D-transient elastohydrodynamic lubrication hip implant model to compare ultra high molecular weight polyethylene with more compliant polycarbonate polyurethane acetabular cups

Wear remains a significant challenge in the design of orthopedic implants such as total hip replacements. Early elastohydrodynamic lubrication modeling has predicted thicker lubrication films in hip replacement designs with compliant polycarbonate polyurethane (PCU) bearing materials compared to stiffer materials like ultra-high molecular weight polyethylene (UHMWPE). The predicted thicker lubrication films suggest improved friction and wear performance. However, when compared to the model predictions, experimental wear studies showed mixed results. The mismatch between the model and experimental results may lie in the simplifying assumptions of the early models such as: steady state conditions, one dimensional rotation and loading, and high viscosities. This study applies a 3D-transient elastohydrodynamic model based on an ISO standard gait cycle to better understand the interaction between material stiffness and film thickness in total hip arthroplasty material couples. Similar to previous, simplified models, we show that the average and central film thickness of PCU (∼0.4μm) is higher than that of UHMWPE (∼0.2μm). However, in the 3D-transient model, the film thickness distribution was largely asymmetric and the minimum film thickness occurred outside of the central axis. Although the overall film thickness of PCU was higher than UHMWPE, the minimum film thickness of PCU was lower than UHMPWE for the majority of the gait cycle. The minimum film thickness of PCU also had a larger range throughout the gait cycle. Both materials were found to be operating between boundary and mixed lubrication regimes. This 3D-transient model reveals a more nuanced interaction between bearing material stiffness and film thickness that supports the mixed results found in experimental wear studies of PCU hip implant designs.

UV-curable fluorinated polycarbonate polyurethane with improved surface properties

A series of UV-curable fluorinated polycarbonate polyurethanes (FCPUAs) were synthesized by modifying polycarbonate polyurethane with 2-(perfluorohexyl)ethanol (PFHE) and glycidyl methacrylate (GMA). The structures of FCPUAs were analyzed with 1H NMR and FTIR. Different contents of FCPUAs were blended into non-fluorinated polycarbonate polyurethane as fluorinated additives. The water and oil contact angles of the films were investigated by contact angle measurement, and the results indicated that an extremely low concentration of FCPUAs could produce a highly hydrophobic and oleophobic coating. The X-ray photoelectron spectroscopic analysis showed that the coating surface was rich in fluorinated species. Besides, the films containing FCPUAs also had great tensile strength, hardness and adhesion.

Electrospun Polyurethane–Gelatin Composite: A New Tissue-Engineered Scaffold for Application in Skin Regeneration and Repair of Complex Wounds

Wound healing is vital for patients with complex wounds including burns. While the gold standard of skin transplantation ensures a surgical treatment to heal wounds, it has its limitations, for example, insufficient donor sites for patients with large burn wounds and creation of wounds and pain when harvesting the donor skin. Therefore, tissue-engineered skin is of paramount importance. The aim of this study is to investigate and characterize an elastomeric acellular scaffold that would demonstrate the ability to promote skin regeneration. A hybrid gelatin-based electrospun scaffold is fabricated via the use of biodegradable polycarbonate polyurethane (PU). It is hypothesized that the addition of PU would enable a tailored degradation rate and an enhanced mechanical strength of electrospun gelatin. Introducing 20% PU to gelatin scaffolds (Gel80-PU20) results in a significant increase in the degradation resistance, yield strength, and elongation of these scaffolds without altering the cell viability. In vivo studies using a mouse excisional wound biopsy grafted with the scaffolds reveals that the Gel80-PU20 scaffold enables greater cell infiltration than clinically established matrices, for example, Integra (dermal regeneration matrix, DRM), a benchmark scaffold. Immunostaining shows fewer macrophages and myofibroblastic cells on the Gel80-PU20 scaffold when compared with the DRM. The findings show that electrospun Gel80-PU20 scaffolds hold potential for generating tissue substitutes and overcoming some limitations of conventional wound care matrices.

Synthesis and characterization of electrospun nanofibrous tissue engineering scaffolds generated from in situ polymerization of ionomeric polyurethane composites

Tissue scaffolds need to be engineered to be cell compatible, have timely biodegradable character, be functional with respect to providing niche cell support for tissue repair and regeneration, readily accommodate multiple cell types, and have mechanical properties that enable the simulation of the native tissue. In this study, electrospun degradable polar hydrophobic ionic polyurethane (D-PHI) scaffolds were generated in order to yield an extracellular matrix-like structure for tissue engineering applications. D-PHI oligomers were synthesized, blended with a degradable linear polycarbonate polyurethane (PCNU), and electrospun with simultaneous in situ UV cross-linking in order to generate aligned nanofibrous scaffolds in the form of elastomeric composite materials. The D-PHI/PCNU scaffold fibre morphology, cross-linking efficiency, surface nature, mechanical properties, in vivo degradation and integration, as well as in vitro cell compatibility were characterized. The results showed that D-PHI/PCNU scaffolds had a high cross-linking efficiency, stronger polar nature, and lower stiffness relative to PCNU scaffolds. In vivo, the D-PHI/PCNU scaffold degraded relatively slowly, thereby enabling new tissue time to form and yielding very good integration with the latter tissue. Based on a study with A10 vascular smooth muscle cells, the D-PHI/PCNU scaffold was able to support high cell viability, adhesion, and expression of typical smooth muscle cell markers after a 7-day culture period, which was comparable to PCNU scaffolds. These characterization results demonstrate that the unique properties of a D-PHI/PCNU scaffold, combined with the benefits of electrospinning, could allow for the generation of a tissue engineered scaffold that mimics important aspects of the native extracellular matrix and could be used for functional tissue regeneration. Statement of SignificanceTissue engineered scaffolds should recapitulate native extracellular matrix features. This study investigates the processing of a classical polycarbonate polyurethane (PCNU) with a cross-linked and degradable ionomeric polyurethane (D-PHI), polymerized via in situ rapid light curing to yield a 3-dimensional co-electrospun nanofibre matrix with chemical diversity and low modulus character. This research advances the use of D-PHI for tissue engineering applications by providing a facile means of changing physical and chemical properties in classical PCNUs without the need to adjust spinning viscosities of the base polymer. Further, the in vivo and cell culture findings set the stage for introducing unique elastic materials which inherently support wound healing, repair, and regeneration in tissues, for applications that require the recapitulation of native extracellular matrix physical features.

Hydrophobic treatment of woven cotton fabrics with polyurethane modified aminosilicone emulsions

Woven cotton fabrics were treated with a polyurethane modified aminosilicone fluid commonly used as a fabric softener. The aminoethylaminopropyl polydimethylsiloxane was modified with an aqueous dispersion of polycarbonate diol polyurethane using isopropyl alcohol as co-solvent resulting in stable micro-emulsions with an average droplet size of 1.5 μm. Polycarbonate polyurethane was chosen due to its good hydrolytic stability and low water absorption levels. Fabrics were treated either by immersion in emulsions or by spray coating. Treated fabrics had static water contact angles exceeding 143 o with droplet shedding angles of less than 50 o depending on the droplet volume. Treated textiles were breathable with vapor permeability levels of 5.6 mg (m day Pa) −1 that was similar to untreated fabrics. Good droplet shedding action was achieved based on the inherent fiber roughness. Accelerated ageing tests corresponding to 5 years using CIEL*a*b standards (7.5 × 10 6 lx∙hours exposure) indicated that no ageing occurred, with the overall color parameter of ΔE < 2.0 indicating invisible color changes to the naked eye. This sustainable approach can be easily scaled and may be a valuable treatment alternative for delicate fabrics commonly encountered in Heritage preservation; but also for many other cotton-based textiles. • An aminosilicone fluid-polyurethane based cotton treatment emulsion was developed. • Textiles could be treated by simple dip or spray coating. • Self-cleaning hydrophobic fabrics result without additional surface texturing. • Treatment does withstand ageing with no visible yellowing.

In vivo endothelialization and neointimal hyperplasia assessment after angioplasty of sheep carotid artery with a novel polycarbonate polyurethane patch.

The aim of this study was to compare two variants of a novel polycarbonate polyurethane prosthesis with polyethylene terephthalate (Dacron) prosthesis in an established sheep model of carotid patch angioplasty. Two variants of the polycarbonate polyurethane prosthesis were used: (1) Polycarbonate polyurethane equal (PCU-e) prosthesis consisted of a multilayered porous structure with equal internal and external layers; (2) Polycarbonate polyurethane with more porous inner layers (PCU-mp) prosthesis had more porous inner layers than external layers. Carotid patch angioplasty was performed in 12 sheep: in six sheep, the PCU-e variant and in the other six sheep, the PCU-mp variant was implanted. Dacron patches were implanted in the contralateral carotid artery of all sheep as a control. Half of the animals with each polycarbonate polyurethane variant were euthanized after two weeks and the other half after eight weeks. Cellular infiltration, endothelialization, and neointimal hyperplasia were examined. All grafts were patent, and no thrombus was seen in any of the harvested arteries. The pores of all the three patch materials allowed infiltration of inflammatory cells, capillaries, and connective tissue. After eight weeks, a nearly complete endothelialization was visible in all patch groups without an obvious difference between the three patch materials. The neointima was thinner in the PCU patches (PCU-e: 56 ± 13 µm, PCU-mp: 119 ± 60 µm) when compared to Dacron patches (156 ± 64 µm) after two weeks. After 8 weeks, a further neointimal growth was detectable, without any significant difference of neointimal thickness between the three patch materials (Dacron: 274 ± 82 µm, PCU-e: 324 ± 98 µm, PCU-mp: 235 ± 59 µm). With the novel polycarbonate polyurethane patch materials, we achieved promising functional and morphological results with 100% patency and nearly complete endothelialization. Our findings showed at least a non-inferiority of the novel polycarbonate polyurethane patch material compared to Dacron. There were no significant differences detected between the two polycarbonate polyurethane patch variants.

Synthesis and Characterization of Electrospun Nanofibrous Tissue Engineering Scaffolds Generated from in Situ Polymerization of Ionomeric Polyurethane Composites

Tissue scaffolds need to be engineered to be cell compatible, have timely biodegradable character, be functional with respect to providing niche cell support for tissue repair and regeneration, readily accommodate multiple cell types, and have mechanical properties that enable the simulation of the native tissue. In this study, electrospun degradable polar hydrophobic ionic polyurethane (D-PHI) scaffolds were generated in order to yield an extracellular matrix-like structure for tissue engineering applications. D-PHI oligomers were synthesized, blended with a degradable linear polycarbonate polyurethane (PCNU), and electrospun with simultaneous in situ UV cross-linking in order to generate aligned nanofibrous scaffolds in the form of elastomeric composite materials. The D-PHI/PCNU scaffold fibre morphology, cross-linking efficiency, surface nature, mechanical properties, in vivo degradation and integration, as well as in vitro cell compatibility were characterized. The results showed that D-PHI/PCNU scaffolds had a high cross-linking efficiency, stronger polar nature, and lower stiffness relative to PCNU scaffolds. In vivo, the D-PHI/PCNU scaffold degraded relatively slowly, thereby enabling new tissue time to form and yielding very good integration with the latter tissue. Based on a study with A10 vascular smooth muscle cells, the D-PHI/PCNU scaffold was able to support high cell viability, adhesion, and expression of typical smooth muscle cell markers after a 7-day culture period, which was comparable to PCNU scaffolds. These characterization results demonstrate that the unique properties of a D-PHI/PCNU scaffold, combined with the benefits of electrospinning, could allow for the generation of a tissue engineered scaffold that mimics important aspects of the native extracellular matrix and could be used for functional tissue regeneration.

In vitro oxidative stability of high strength siloxane poly(urethane-urea) elastomers based on linked-macrodiol.

In vitro oxidative stability of two siloxane poly(urethane urea)s synthesized using 4,4'-methylenediphenyl diisocyanate (in SiPUU-1) and Isophorone diisocyanate (in SiPUU-2) linked soft segment was evaluated using 20% H2 O2 and 0.1 mol/L CoCl2 solution at 37°C under 150% strain. Commercially available siloxane polyurethane (Elast-Eon™ 2A) and polyether polyurethane (ChronoThane P™ 80A) were used as negative and positive controls, respectively. ChronoSil™ 80A was included as another commercially available polycarbonate polyurethane. Scanning electron microscopic (SEM) examinations, attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, and molecular weight reduction revealed the extensive degradation of ChronoThane P™ 80A after 90 days while SiPUU-1, SiPUU-2 and Elast-Eon™ 2A showed no noticeable surface degradation. ChronoSil™ 80A showed degradation in both soft and hard segments. Tensile testing was carried out only on unstrained polyurethanes for 90 days. ChronoThane P™ 80A showed 35% loss in ultimate tensile strength and it was only 13-14% for SiPUU-1 and Elast-Eon™ 2A. However, the tensile strength of ChronoSil™ 80A was not significantly affected. The results of this study proved that SiPUU-1 possess oxidative stability comparable with Elast-Eon™ 2A. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B:2557-2565, 2019.