Poly Ester Urethane Urea Research Articles

FOIM: Thermal Foaming of Shape Memory Polyurethane Foil.

This work introduces the semi-finished product FOIM, a neologism from FOIl and foaM, a phase segregated polyester urethane urea (PEUU) foam, which is synthesized from poly(1,6-hexylene adipate) diol, 4,4'-methylene diphenyl diisocyanate, polyethylene glycol and water as blowing agent. The PEUU is obtained by following a one-shot synthesis and is characterized by a hard/soft segment ratio of 1.06 and an open pore content of 78%. Differential scanning calorimetry reveals a melting peak at 45°C and a crystallization signal at 14°C, both of which are associated with the phase transitions of the soft segment. The glass transition temperature, which is determined as a local maximum within the tanδ using dynamic mechanical analysis, is 1°C. During programming, the foam is heavily compressed at 60°C. Once unloaded at 23°C, a translucent foil, the FOIM, is obtained. When reheated to 60°C, the foil switches back to the foam due to its pronounced shape memory properties. Intriguingly, the structure remains largely unaffected by the drastic deformation as indicated by buoyancy and heat transmission measurements. The ease of manufacture and functionality makes the technology attractive for applications, in which both low transport volumes and drastic shape changes are desired.

Multifunctional hybrid poly(ester-urethane)urea/resveratrol electrospun nanofibers for a potential vascularizing matrix.

The challenges for clinical application of small-diameter vascular graft are mainly acute/chronic thrombosis, inadequate endothelialization, intimal hyperplasia caused by inflammation, oxidative stress, and the mismatch of mechanical compliance after transplantation. How to construct an effective regenerative microenvironment through a material with uniform dispersion of active components is the premise of maintaining patency of a vascular graft. In this study, we have compounded poly(ester-urethane)urea (PEUU) with various optimized concentrations of resveratrol (Res) by homogeneous emulsion blending, followed by electrospinning into the hybrid PEUU/Res nanofibers (P/R-0, P/R-0.5, P/R-1.0, and P/R-1.5). Then the microstructure, surface wettability, mechanical properties, degradation, Res sustained release properties, hemocompatibility, and cytocompatibility of P/R were evaluated comprehensively. The results indicate that Res can be gradually released from the P/R, and both the hydrophilicity and antioxidant ability of the nanofiber gradually increase with the increase of Res content. Moreover, with the increase of Res, the viability and proliferation behavior of HUVECs were significantly improved. Meanwhile, tube formation and migration experiments showed that Res promoted the formation of a neovascularization network. In brief, it is concluded that P/R-1.0 is the optimal candidate with a uniform microstructure, moderate wettability, optimized mechanical properties, reliable hemocompatibility and cytocompatibility, and strongest ability to promote endothelial growth for the vascularizing matrix.

Sprayable Biodegradable Polyester-Urethane-Urea Mulching Treatment Increases Abundance of Soil Microbes

The paper investigates for the first time the impact of a novel sprayable, biodegradable polyester-urethane-urea (PEUU) mulch on the microbial community composition of an agricultural soil. In this study changes to the composition of the soil microbial community and in soil enzyme activity involved in nutrient cycling were monitored on tomato plants grown under controlled greenhouse conditions. Particular attention was given to impacts on the relative changes in abundance of soil microbes. The PEUU mulch reduced the abundance of a small number of soil microbe taxa, but also provided an environment in which some taxa, which were comparatively rare in initial and unmulched soils, thrived. Importantly, the relative abundances of Azospirillum, Noviherbaspirillum, Exophiala, Phoma, Chaetomium and Clonostachys species all increased in soils treated with PEUU mulch. Principal coordinates analysis revealed the microbial community composition on PEUU films alone and in PEUU treated soil were most similar, while the PEUU films’ microbial community differed the most from the initial soil’s microbial community. These results indicate that from an agricultural productivity and an environmental safety standpoint the use of PEUU mulch may be preferable to PE and could provide additional plant growth benefits by increasing the abundance of soil microbes.

Understanding the Impact of Soil Characteristics and Field Management Strategies on the Degradation of a Sprayable, Biodegradable Polymeric Mulch

The use of non-degradable plastic mulch has become an essential agricultural practice for increasing crop yields, but continued use has led to contamination problems and in some cropping areas decreases in agricultural productivity. The subsequent emergence of biodegradable plastic mulches is a technological solution to these issues, so it is important to understand how different soil characteristics and field management strategies will affect the rate at which these new materials degrade in nature. In this work, a series of lab-scale hydrolytic degradation experiments were conducted to determine how different soil characteristics (type, pH, microbial community composition, and particle size) affected the degradation rate of a sprayable polyester–urethane–urea (PEUU) developed as a biodegradable mulch. The laboratory experiments were coupled with long-term, outdoor, soil degradation studies, carried out in Clayton, Victoria, to build a picture of important factors that can control the rate of PEUU degradation. It was found that temperature and acidity were the most important factors, with increasing temperature and decreasing pH leading to faster degradation. Other important factors affecting the rate of degradation were the composition of the soil microbial community, the mass loading of PEUU on soil, and the degree to which the PEUU was in contact with the soil.

4D-Printed Tool for Compressing a Shape Memory Polyurethane Foam during Programming.

Although several force application concepts are known that can be used to deform shape memory polymers (SMPs) within the scope of programming, controlled deformation is challenging in the case of samples with a cylinder-like shape, which need to be homogeneously compressed starting from the lateral surface. To solve this problem, this contribution follows a material approach that takes advantage of four-dimensional (4D) printing. Fused filament fabrication (FFF) was used as an additive manufacturing (AM) technique to produce a thermoresponsive tool in a cylindrical shape from a polyether urethane (PEU) having a glass transition temperature (Tg) close to 55 °C, as determined by differential scanning calorimetry (DSC). Once it was 4D-printed, a sample of laser cut polyester urethane urea (PEUU) foam with a cylindrical wall was placed inside of it. Subsequent heating to 75 °C and keeping that temperature constant for 15 min resulted in the compression of the foam, because the internal stresses of the PEU were transferred to the PEUU, whose soft segments were completely molten at 65 °C as verified by DSC. Upon cooling to -15 °C and thus below the offset temperature of the soft segment crystallization transition of the PEUU, the foam was fixed in its new shape. After 900 days of storage at temperatures close to 23 °C, the foam recovered its original shape upon reheating to 75 °C. In another experiment, a 4D-printed cylinder was put into hibernation for 900 days before its thermoresponsiveness was investigated. In the future, 4D-printed tools may be produced in many geometries, which fit well to the shapes of the SMPs to be programmed. Beyond programming SMP foams, transferring the forces released by 4D-printed tools to other programmable materials can further expand technical possibilities.

Electrospun membranes of diselenide-containing poly(ester urethane)urea for in situ catalytic generation of nitric oxide

Nitric oxide (NO) plays an important role as a signalling molecule in the biological system. Organoselenium-coated or grafted biomaterials have the potential to achieve controlled NO release as they can catalyse decomposition of endogenous S-nitrosothiols to NO. However, such biomaterials are often challenged by the loss of the catalytic sites, which can affect the stability in tissue repair applications. In this work, we prepare a diselenide-containing poly(ester urethane)urea (SePEUU) polymer with Se–Se in the backbone, which is further electrospun into fibrous membranes by blending with poly(ester urethane)urea (PEUU) without diselenide bonds. The presence of catalytic sites in the main chain demonstrates stable and long-lasting NO catalytic activity, while the porous structure of the fibrous membranes ensures uniform distribution of the catalytic sites and better contact with the donor-containing solution. PEUU/SePEUU50 in 50/50 mass ratio has a physiologically adapted rate of NO release, with a sustained generation of NO after exposure to PBS at 37 °C for 30 d. PEUU/SePEUU50 has a low hemolysis and protein adsorption, with mechanical properties in the wet state matching those of natural vascular tissues. It can promote the adhesion and proliferation of human umbilical vein endothelial cells in vitro and control the proliferation of vascular smooth muscle cells in the presence of NO generation. This study exhibits the electrospun fibrous membranes have potential for utilizing as hemocompatible biomaterials for regeneration of blood-contacting tissues.

Nerve Wrap for Local Delivery of FK506/Tacrolimus Accelerates Nerve Regeneration.

Peripheral nerve injuries (PNIs) occur frequently and can lead to devastating and permanent sensory and motor function disabilities. Systemic tacrolimus (FK506) administration has been shown to hasten recovery and improve functional outcomes after PNI repair. Unfortunately, high systemic levels of FK506 can result in adverse side effects. The localized administration of FK506 could provide the neuroregenerative benefits of FK506 while avoiding systemic, off-target side effects. This study investigates the utility of a novel FK506-impregnated polyester urethane urea (PEUU) nerve wrap to treat PNI in a previously validated rat infraorbital nerve (ION) transection and repair model. ION function was assessed by microelectrode recordings of trigeminal ganglion cells responding to controlled vibrissae deflections in ION-transected and -repaired animals, with and without the nerve wrap. Peristimulus time histograms (PSTHs) having 1 ms bins were constructed from spike times of individual single units. Responses to stimulus onsets (ON responses) were calculated during a 20 ms period beginning 1 ms after deflection onset; this epoch captures the initial, transient phase of the whisker-evoked response. Compared to no-wrap controls, rats with PEUU-FK506 wraps functionally recovered earlier, displaying larger response magnitudes. With nerve wrap treatment, FK506 blood levels up to six weeks were measured nearly at the limit of quantification (LOQ ≥ 2.0 ng/mL); whereas the drug concentrations within the ION and muscle were much higher, demonstrating the local delivery of FK506 to treat PNI. An immunohistological assessment of ION showed increased myelin expression for animals assigned to neurorrhaphy with PEUU-FK506 treatment compared to untreated or systemic-FK506-treated animals, suggesting that improved PNI outcomes using PEUU-FK506 is mediated by the modulation of Schwann cell activity.

Polyester urethane urea (PEUU) functionalization for enhanced anti-thrombotic performance: advancing regenerative cardiovascular devices through innovative surface modifications.

Introduction: Thrombogenesis, a major cause of implantable cardiovascular device failure, can be addressed through the use of biodegradable polymers modified with anticoagulating moieties. This study introduces a novel polyester urethane urea (PEUU) functionalized with various anti-platelet deposition molecules for enhanced antiplatelet performance in regenerative cardiovascular devices. Methods: PEUU, synthesized from poly-caprolactone, 1,4-diisocyanatobutane, and putrescine, was chemically oxidized to introduce carboxyl groups, creating PEUU-COOH. This polymer was functionalized in situ with polyethyleneimine, 4-arm polyethylene glycol, seleno-L-cystine, heparin sodium, and fondaparinux. Functionalization was confirmed using Fourier-transformed infrared spectroscopy and X-ray photoelectron spectroscopy. Bio-compatibility and hemocompatibility were validated through metabolic activity and hemolysis assays. The anti-thrombotic activity was assessed using platelet aggregation, lactate dehydrogenase activation assays, and scanning electron microscopy surface imaging. The whole-blood clotting time quantification assay was employed to evaluate anticoagulation properties. Results: Results demonstrated high biocompatibility and hemocompatibility, with the most potent anti-thrombotic activity observed on pegylated surfaces. However, seleno-L-cystine and fondaparinux exhibited no anti-platelet activity. Discussion: The findings highlight the importance of balancing various factors and addressing challenges associated with different approaches when developing innovative surface modifications for cardiovascular devices.

BIO26: Engineering Anti-platelet polymers for regenerative cardiovascular applications

Thrombogenesis is the main failure cause of implantable cardiovascular devices. Thrombus formation not only occludes devices but exacerbates immune responses responsible for foreign body reaction. Biodegradable polymers modified with anticoagulating moieties represent a strategy to overcome these limitations. Herein, we propose the use of a novel polyester urethane urea (PEUU) with pendant carboxyl groups for functionalization with different anti-platelet deposition molecules. PEUU was synthesized from PCL (Polycaprolactone), 1,4-diisocyanatobutane and putrescine, and then chemically oxidized to introduce carboxyl groups in the polymer backbone (PEUU-COOH). PEUU-COOH was functionalized in-situ with Polyethyleneimine mW 400 (PEI), 4 arm Polyethylene Glycol (PEG-4-Arm-NH2), seleno-L-cystine, heparin sodium and fondaporinux as anti-platelet deposition molecules. After solvent casting, functionalization was confirmed via Fourier-transformed infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Metabolic activity (MTT) and hemolysis assays were performed to validate biocompatibility. Anti-platelet activity of PRP exposed films was examined via a platelet aggregation assay, through an activation assay via lactate dehydrogenase (LDH), and by surface imaging with scanning electron microscopy (SEM). Whole-blood clotting time quantification assay was carried out to evaluate anticogulating properties. Upon oxidation, PEUU exhibited COOH pendant groups that were successfully employed to conjugate the anti-platelet molecules, obtaining homogeneous films. Overall cytotoxicity was below 20% and the hemolysis was below 5%, suggesting high biocompatibility and hemocompatibility. The most potent anticoagulant activity was obtained for heparin-functionalized materials followed by PEG-4-Arm-NH2 and PEI. Surprisingly, Seleno-L-cystine and Fondaporinux showed no anti-platelet activity. Results indicate that the polymers introduced here are a promising strategy to avoid thrombogenesis in vascular grafts.

Electrospun membranes of carboxylated poly(ester urethane)urea/gelatin encapsulating pterostilbene for adaptive and antioxidative purposes

Oxidative stress caused by the harsh microenvironment after implantation of an artificial graft with mismatching mechanical properties usually triggers inflammation responses, which have adverse impacts on tissue regeneration. For coping with these problems, in this work, bioactive fibrous scaffolds were developed from specially synthesized carboxylated poly(ester urethane)urea (PEUU) and gelatin (Gel) by encapsulating pterostilbene (Pte) for the first time. The prepared electrospun membranes exhibited self-adaptable mechanical properties with high elasticity owing to the bonded electrospun fibers, cross-linking network between PEUU and Gel, and the inherent flexibility of the PEUU polymer in the fibrous matrix. The PEUU/Gel/Pte electrospun membrane containing 7% Pte could promote in vitro proliferation of human umbilical vein endothelial cells, and regulate vascular smooth muscle cells with excellent antioxidant properties via free radical scavenging. In vivo results in a rat subcutaneous implantation model further demonstrated the positive effect of the specially prepared PEUU/Gel/Pte scaffold on both normal cell growth and anti-inflammatory by promoting cellularization and polarizing macrophages toward the M2 phenotype. These PEUU/Gel/Pte electrospun membranes with adaptability benefit to tissue regeneration by modulating inflammation responses, especially applications in vascular regeneration.

A better understanding of the polymeric irradiation using physico-electrochemical characteristics

Poly(ester-urethane) urea (PEUU) based on ethanolamine as a chain extender contain hydroxyl and amino groups was chemically synthesized using 1,1'-methylenebis(4-isocyanatobenzene) MDI diisocyanates, and castor oil. One step polymerization procedure has been used to complete the PEUU formation and this polymeric target was irradiated with different doses (100, 250, 400, and 600 kGy) of gamma rays. A full physico-electrochemical characterization package was performed on the solid surfaces, radiated vs. non-irradiated, for a better understanding of the structure changes. To that end, Fourier transform infrared spectroscopy (FTIR), and the morphological features were characterized by the scanning electron microscope (SEM). Thermal stability was investigated using differential scanning calorimetry (DSC), while the crystallinity and electrochemical properties were explored by the X-ray diffraction (XRD), and cyclic voltammetry (CV), respectively. Eventually, swelling, crosslinking density, mechanical strength, water absorption, and contact angle measurements were discussed. Ultimately, the crosslinking density was discovered to be irradiated dependent. Worth mentioning here, this kind of study is recommended as a protocol that could be applied on other polymeric targets exposed to electromagnetic radiations.

3D printing of polymeric Coatings on AZ31 Mg alloy Substrate for Corrosion Protection of biomedical implants

AbstractMagnesium (Mg) alloys show promise in biomedical implants due to their excellent mechanical strength, biocompatibility and biodegradability. However, their rapid degradation rates in vivo induce toxicity and reduce their mechanical strength thereby, limiting their widespread usage. Our group employs a 3D inkjet printing technique for polymeric surface modification of bioresorbable AZ31 Mg alloy towards corrosion control. Thin films of three proprietary formulations of elastomeric poly (ester urethane) urea (PEUU) embedded with an anti‐proliferative drug paclitaxel (Taxol) were coated on biodegradable AZ31 Mg coupons. Multilayer coatings of 5 and 20 layers were deposited for virgin (PEUU‐V), PEUU with phosphorylcholine (PEUU‐PC) and PEUU with sulfobetaine (PEUU‐SB). Coating thicknesses of 8 µm and 19 µm were observed for 5‐layer and 20‐layer coatings, respectively. Surface morphology results depicted the presence of Taxol beads on PEUU‐V and PEUU‐SB coatings due to precipitation. An equivalent circuit model was used to calculate the polarization resistance values and revealed that the polymeric coatings provided a significant protective effect on the corrosion rate of AZ31 Mg alloy. Electrochemical impedance spectroscopy measurements indicated that PEUU‐SB offered the least resistance to corrosion and had the highest porosity (35.6%) among all the polymeric coatings. PEEU‐V polymeric coatings offered the greatest polarization resistance with the least porosity (10.5%). Statistical analysis confirmed that the 20‐layer coating thickness had a significantly higher polarization resistance than the 5‐layer coatings. This research lays the foundation for developing corrosion control drug‐eluting coatings for cardiovascular and other medical device applications via surface modification using 3D inkjet printing.

Covalent grafting of PEG and heparin improves biological performance of electrospun vascular grafts for carotid artery replacement

Rapid endothelialization of small-diameter vascular grafts remains a significant challenge in clinical practice. In addition, compliance mismatch causes intimal hyperplasia and finally leads to graft failure. To achieve compliance match and rapid endothelialization, we synthesized low-initial-modulus poly(ester-urethane)urea (PEUU) elastomer and prepared it into electrospun tubular grafts and then functionalized the grafts with poly(ethylene glycol) (PEG) and heparin via covalent grafting. The PEG- and heparin-functionalized PEUU (PEUU@PEG-Hep) graft had comparable mechanical properties with the native blood vessel. In vitro data demonstrated that the grafts are of good cytocompatibility and blood compatibility. Covalent grafting of PEG and heparin significantly promoted the adhesion, spreading, and proliferation of human umbilical vein endothelial cells (HUVECs) and upregulated the expression of vascular endothelial cell-related genes, as well as increased the capability of grafts in preventing platelet deposition. In vivo assessments indicated good biocompatibility of the PEUU@PEG-Hep graft as it did not induce severe immune responses. Replacement of resected carotid artery with the PEUU@PEG-Hep graft in a rabbit model showed that the graft was capable of rapid endothelialization, initiated vascular remodeling, and maintained patency. This study demonstrates the PEUU@PEG-Hep vascular graft with compliance match and efficacious antithrombosis might find opportunities for bioactive blood vessel substitutes.

A Cell-free Biodegradable Synthetic Artificial Ligament for the Reconstruction of Anterior Cruciate Ligament in a Rat Model

Traditional Anterior Cruciate Ligament (ACL) reconstruction is commonly performed using an allograft or autograft and possesses limitations such as donor site morbidity, decreased range of motion, and potential infection. However, a biodegradable synthetic graft could greatly assist in the prevention of such restrictions after ACL reconstruction. In this study, artificial grafts were generated using "wet" and "dry" electrospinning processes with a biodegradable elastomer, poly (ester urethane) urea (PEUU), and were evaluated in vitro and in vivo in a rat model. Four groups were established: (1) Wet PEUU artificial ligament, (2) Dry PEUU artificial ligament, (3) Dry polycaprolactone artificial ligament (PCL), and (4) autologous flexor digitorum longus tendon graft. Eight weeks after surgery, the in vivo tensile strength of wet PEUU ligaments had significantly increased compared to the other synthetic ligaments. These results aligned with increased infiltration of host cells and decreased inflammation within the wet PEUU grafts. In contrast, very little cellular infiltration was observed in PCL and dry PEUU grafts. Micro-computed tomography analysis performed at 4 and 8 weeks postoperatively revealed significantly smaller bone tunnels in the tendon autograft and wet PEUU groups. The Wet PEUU grafts served as an adequate functioning material and allowed for the creation of tissues that closely resembled the ACL.

Shape Memory Polymer Foam with Programmable Apertures

In this work, a novel type of polyester urethane urea (PEUU) foam is introduced. The foam was produced by reactive foaming using a mixture of poly(1,10–decamethylene adipate) diol and poly(1,4–butylene adipate) diol, 4,4′-diphenylmethane diisocyanate, 1,4–butanediol, diethanolamine and water as blowing agent. As determined by differential scanning calorimetry, the melting of the ester-based phases occurred at temperatures in between 25 °C and 61 °C, while the crystallization transition spread from 48 °C to 20 °C. The mechanical properties of the foam were simulated with the hyperplastic models Neo-Hookean and Ogden, whereby the latter showed a better agreement with the experimental data as evidenced by a Pearson correlation coefficient R² above 0.99. Once thermomechanically treated, the foam exhibited a maximum actuation of 13.7% in heating-cooling cycles under a constant external load. In turn, thermal cycling under load-free conditions resulted in an actuation of more than 10%. Good thermal insulation properties were demonstrated by thermal conductivities of 0.039 W·(m·K)−1 in the pristine state and 0.052 W·(m·K)−1 in a state after compression by 50%, respectively. Finally, three demonstrators were developed, which closed an aperture or opened it again simply by changing the temperature. The self-sufficient material behavior is particularly promising in the construction industry, where programmable air slots offer the prospect of a dynamic insulation system for an adaptive building envelope.

Covalent Self-Assembly of PEG and Heparin Improves Biological Performance of Electrospun Vascular Grafts for Carotid Artery Replacement

Rapid endothelialization of small-diameter vascular grafts remains a significant challenge in clinical practice. In addition, compliance mismatch causes intimal hyperplasia and finally leads to graft failure. To achieve compliance match and rapid endothelialization, we synthesized low-initial-modulus poly(ester-urethane)urea (PEUU) elastomer and prepared it into electrospun tubular grafts and then functionalized the grafts with poly(ethylene glycol) (PEG) and heparin via covalent self-assembly. The PEG- and heparin-functionalized PEUU (PEUU@PEG-Hep) graft had comparable mechanical properties with the native blood vessel. In vitro data demonstrated that the grafts are of great cytocompatibility and blood compatibility. Covalent self-assembly of PEG and heparin significantly promoted the adhesion, spreading, and proliferation of human umbilical vein endothelial cells (HUVECs) and upregulated the expression of vascular endothelial cell-related genes, as well as increased the capability of grafts in preventing platelet deposition. In vivo assessments indicated good biocompatibility of the PEUU@PEG-Hep graft as it did not induce severe immune responses. Replacement of resected carotid artery with the PEUU@PEG-Hep graft in a rabbit model showed that the graft was capable of rapid endothelialization, initiated vascular remodeling, and maintained patency. This study demonstrates the synergistic effects of compliance match and efficacious antithrombosis of synthetic grafts for blood vessel regeneration.

Macroporous 3D Scaffold with Self-Fitting Capability for Effectively Repairing Massive Rotator Cuff Tear.

The postoperative retear rate of direct repair of massive rotator cuff tear has risen up to 40% because of the dissatisfied tendon-to-bone healing and poor regenerative potential of remnant rotator cuff tissue. A biological scaffold that connects the remnant rotator cuff tissue and bone might be a promising substitute. In the present study, we have developed a macroporous three-dimensional scaffold poly(ester-urethane)urea (PEUU), with self-fitting capability employing thermally induced phase separation (TIPS) technique. The scaffold provides oriented connected macropores for cells migration, and promoted tendon-to-bone healing on the basis of surgical repair. The scaffolds were characterized by scanning electron microscopy, stress-strain test and cell biocompatibility study. In vitro studies exhibited that PEUU scaffold with suitable elastic mechanical properties can better support proliferation and migration of rabbit bone mesenchymal stem cells (RBMSCs). After three months postreconstruction of massive rotator cuff tear in a rabbit model using PEUU scaffold, there was complete regeneration of rotator cuff with physical tendon-to-bone interface and continuous tendon tissue, as observed from histological analysis. Further, biomechanical testing demonstrated that rotator cuff induced by PEUU scaffold had no significant difference as compared to normal rotator cuff. This macroporous, mechanically matched scaffold is potentially suitable for the application in massive rotator cuff repair. In conclusion, this study demonstrates the high efficiency of the macroporous 3D scaffold with self-fitting capability in facilitating rotator cuff regeneration.

Electrospun Poly(p-dioxanone)/Poly(ester-urethane)ureas Composite Nanofibers for Potential Heart Valve Tissue Reconstruction

Electrospun nanofibrous mats represent a new generation of medical textiles with promising applications in heart valve tissue reconstruction. It is important for biomaterials to mimic the biological and mechanical microenvironment of native extracellular matrix (ECM). However, the major challenges are still remaining for current biomedical materials, including appropriate mechanical properties, biocompatibility, and hemocompatibility. In the present work, the novel composite nanofibrous mats of poly(p-dioxanone) (PDO) and poly(ester-urethane)ureas (PEUU) are fabricated by electrospinning system. The optimal combination ratio of PDO to PEUU may balance the mechanical properties and cellular compatibility to match the newly formed tissue. In PDO/PEUU composite nanofibrous mats, PEUU can provide the biomimetic elastomeric behavior, and PDO could endow the excellent biocompatibility. In comparison to nanofibrous mat of neat PDO, the composite showed significantly improved mechanical properties, with 5-fold higher initial elongation at break. Furthermore, human umbilical vein endothelial cells (HUVECs) were cultured on the composite to evaluate its ability to rapidly endothelialize as heart valve tissue engineering. The results revealed that PDO/PEUU composite nanofibrous mats could promote cell adhesion and proliferation, especially for the ratio of 60/40. Overall, PDO/PEUU composite nanofibrous mats (60/40) show the excellent mechanical properties, appropriate biocompatibility and hemocompatibility which meet the necessary norm for tissue engineering and may be suitable for potential heart valve tissue reconstruction.

Frost-Resistant Polyurethane-Urea Materials Based on Oligoethers

Physicomechanical behavior of cross-linked segmented polyester urethane ureas with poly(tetramethylene oxide) segments of varied molecular mass, plasticized with di-(2-ethylhexyl) cebacate, was considered. Data on how the structure of flexible and rigid segments affects the physicomechanical properties of the plasticized material, including those at low temperatures, are presented. Ways were determined for obtaining the optimal hybrid structure of the polymers under study for developing materials with enhanced frost resistance.

Preparation and evaluation of poly(ester-urethane) urea/gelatin nanofibers based on different crosslinking strategies for potential applications in vascular tissue engineering.

Due to the brittleness of gelatin, the resulting absence of mechanical performance restricts its applications in vascular tissue engineering. In this research, the fabrication of poly(ester-urethane) urea/gelatin (PU75) nanofibers via an electrospinning technique, followed by different crosslinking methods, resulted in the improvement of its mechanical properties. Poly(ester urethane) urea (PEUU) nanofibrous scaffolds and PU75-based nanofibrous scaffolds were characterized using scanning electron microscopy (SEM), attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, wide-angle X-ray diffraction (WAXRD), a mechanical properties test, a cytocompatibility assay, a hemolysis assay, and a histological analysis. Water contact angle (WCA) tests confirmed that the PU75-GA (PU75 nanofibers crosslinked with glutaraldehyde vapor) nanofibrous scaffold surfaces became more hydrophilic compared with other crosslinked nanofibrous scaffolds. The results show that the PU75-GA nanofibrous scaffold exhibited a combination of excellent mechanical properties, suitable pore diameters, hydrophilic properties, good cytocompatibility, and reliable hemocompatibility. Overall, PU75-GA nanofibers may be a potential scaffold for artificial blood vessel construction.