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3D bioprinting of elastic cartilage tissues that are mechanically and structurally comparable to their native counterparts, while exhibiting favorable cellular behavior, is an unmet challenge. A practical solution for this problem is the multi-material bioprinting of thermoplastic polymers and cell-laden hydrogels using multiple nozzles. However, the processing of thermoplastic polymers requires high temperatures, which can damage hydrogel-encapsulated cells. In this study, the authors developed waterborne polyurethane (WPU)-polycaprolactone (PCL) composites to allow multi-material co-printing with cell-laden gelatin methacryloyl (GelMA) hydrogels. These composites can be extruded at low temperatures (50-60 °C) and high speeds, thereby reducing heat/shear damage to the printed hydrogel-capsulated cells. Furthermore, their hydrophilic nature improved the cell behavior in vitro. More importantly, the bioprinted structures exhibited good stiffness and viscoelasticity compared to native elastic cartilage. In summary, this study demonstrated low-temperature multi-material bioprinting of WPU-PCL-based constructs with good mechanical properties, degradation time-frames, and cell viability, showcasing their potential in elastic cartilage bio-fabrication and regeneration to serve broad biomedical applications in the future., (© 2024 Wiley‐VCH GmbH.)

Three-dimensional (3D) printing provides a new approach of fabricating implantable products because it permits a flexible manner to extrude complex and customized shapes of the tissue scaffolds. Compared with other printable biomaterials, the polyurethane elastomer has several merits, including excellent mechanical properties and good biocompatibility. However, some intrinsic behavior, especially its high melting point and slow rate of degradation, hampered its application in 3D printed tissue engineering. Herein, we developed a 3D printable amino acid modified biodegradable waterborne polyurethane (WBPU) using a water-based green chemistry process. The flexibility of this material endows better compliance with tissue during implantation and prevents high modulus transplants from scratching surrounding tissues. The histocompatibility experiments show that the WBPU induces no apparent acute rejection or inflammation in vivo. We successfully fabricated a highly flexible WBPU scaffold by deposition 3D printing technology at a low temperature (50°C ~ 70 °C), and the printed products could support the adhesion and proliferation of chondrocytes and fibroblasts. The printed blocks possessed controllable degradability due to the different amounts of hydrophilic chain extender and did not cause accumulation of acidic products. In addition, we demonstrated that our WBPU is highly applicable for implantable tissue engineering because there is no cytotoxicity during its degradation. Taken together, we envision that this printable WBPU can be used as an alternative biomaterial for tissue engineering with low temperature printing, biodegradability, and compatibility.

Anti-relapse therapy after surgery plays a critical role in cancer therapy. New strategies maximizing the delivery of drugs to tumor cells while reducing toxic side effects on normal tissues and organs are still urgently required. In order to solve the problems of the poor delivery and inadequate distribution of cytotoxic chemotherapeutic drugs in the clinical application, an ultrasound-controllable and implantable release-system that utilized waterborne polyurethane (WPU) and chitosan (CS) composite membrane as drug carrier with wide flexible loading capacity for doxorubicin (DOX) was described in present work. Benefiting from the hydrophilic segment in WPU and bioactivity of amino groups on side chains of CS, the resulting composite films exhibited fine biodegradability, favorable cytocompatibility and excellent blood compatibility. The in vitro release studies illustrated that the drug-loading membranes displayed a well sustained release effect manifested in slow release, stability and no sudden release, and the DOX was able to release in an ultrasound-controlled manner. Cellular uptake assay and CCK 8 assay showed that the DOX can be released efficiently from the drug-loading matrix and taken up by tumor cells. As a means of adjuvant local treatment, this work provided a facile approach to the design of ultrasound-regulated membrane matrix that is highly beneficial not only due to the higher and long-term therapeutic efficiency, and improvement of utilization efficiency of chemotherapeutic drugs but also the low toxicity to normal cells., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The aim of this study was to introduce bioactivity to the electrospun coating for implantable glucose biosensors. Coaxial fibre membranes having polyurethane as the core and gelatin as the shell were produced using a range of polyurethane concentrations (2, 4, 6 and 8% wt/v) while keeping gelatin concentration (10% wt/v) constant in 2,2,2-trifluoroethanol. The gelatin shell was stabilized using glutaraldehyde vapour. The formation of core-shell structure was confirmed using transmission/scanning electron microscopy and FTIR. The coaxial fibre membranes showed uniaxial tensile properties intermediate to that of the pure polyurethane and the gelatin fibre membranes. The gelatin shell increased hydrophilicity and glucose transport flux across the coaxial fibre membranes. The coaxial fibre membranes having small fibre diameter (541 nm) and a thick gelatin shell (52%) did not affect the sensor sensitivity, but decreased sensor's linearity in the long run. In contrast, thicker coaxial fibre membranes (1133 nm) having a thin gelatin shell (34%) maintained both sensitivity and linearity for the 84 days of the study period. To conclude, polyurethane-gelatin coaxial fibre membranes, due to their faster permeability to glucose, tailorable mechanical properties and bioactivity, are potential candidates for coatings to favourably modify the host responses to extend the reliable in vivo lifetime of implantable glucose biosensors.

This study reports methods for coating miniature implantable glucose biosensors with electrospun polyurethane (PU) membranes, their effects on sensor function and efficacy as mass-transport limiting membranes. For electrospinning fibres directly on sensor surface, both static and dynamic collector systems, were designed and tested. Optimum collector configurations were first ascertained by FEA modelling. Both static and dynamic collectors allowed complete covering of sensors, but it was the dynamic collector that produced uniform fibro-porous PU coatings around miniature ellipsoid biosensors. The coatings had random fibre orientation and their uniform thickness increased linearly with increasing electrospinning time. The effects of coatings having an even spread of submicron fibre diameters and sub-100 μm thicknesses on glucose biosensor function were investigated. Increasing thickness and fibre diameters caused a statistically insignificant decrease in sensor sensitivity for the tested electrospun coatings. The sensors' linearity for the glucose detection range of 2-30 mM remained unaffected. The electrospun coatings also functioned as mass-transport limiting membranes by significantly increasing the linearity, replacing traditional epoxy-PU outer coating. To conclude, electrospun coatings, having controllable fibro-porous structure and thicknesses, on miniature ellipsoid glucose biosensors were demonstrated to have minimal effect on pre-implantation sensitivity and also to have mass-transport limiting ability., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

A nasal stent capable of preventing adhesions and inflammation is of great value in treating nasal diseases. In order to solve the problems of tissue adhesion and inflammation response, we prepared plasticized bacterial cellulose (BCG) and waterborne polyurethane (WPU) composite with antibacterial function used as a novel nasal stent. The gelation behavior of BCG could contribute to protecting the paranasal sinus mucosa; meanwhile, the WPU with improved mechanical property was aimed at supporting the narrow nasal cavity. The thickness, size and the supporting force of the nasal stent could be adjusted according to the specific conditions of the nasal. Thermogravimetric analysis, contact angle and water absorption test were applied to investigate the thermal, hydrophilic and water absorption properties of the composite materials. The composite materials loaded with poly(hexamethylene biguanide) hydrochloride maintained well antibacterial activity over 12 days. Animal experiments further revealed that the mucosal epithelium mucosae damage of BCG−WPU composite was minor compared with that of WPU. This new type of drug-loaded nasal stent can effectively address the postoperative adhesions and infections while ensuring the health of nasal mucosal, and thus has an immense clinical application prospects in treating nasal diseases. [ABSTRACT FROM AUTHOR]

A series of bio-based polyurethane flexible foams were synthesized by substituting polyether polyol with castor oil and polyethylene glycol (PEG). The influence of the castor oil component in the prepolymers on the structure and properties of the castor oil-based polyurethane flexible foams were investigated and compared. FTIR (Fourier transform infrared spectroscopy) results confirmed that bio-based polyurethane was successfully synthesized by castor oil, PEG and MDI (diphenyl methane diisocyanate), and its urethane group content decreased as the castor oil content increased from 40 to 60 wt.%. TG (thermogravimetry) and DTG (derivative thermogravimetry) results showed that the thermal degradation of the bio-based polyurethane flexible foams occurred at about 150, 320 and 420 °C. The Young's modulus improved from 0.196 to 1.235 KPa and the compression resilience improved from 97.76 to 99.65 % with increased content of castor oil. Moreover, these bio-based foams exhibited lower water absorption and higher contact angle with increased castor oil content. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this study was to develop polyurethane (PU) based fibro-porous membranes and to investigate the size-effect of hierarchical porous structure on permeability and surface properties of the developed electrospun membranes. Non-woven Selectophore™ PU membranes having tailored fibre diameters, pore sizes, and thickness were spun using electrospinning, and their chemical, physical and glucose permeability properties were characterised. Solvents, solution concentration, applied voltage, flow rate and distance to collector, each were systematically investigated, and electrospinning conditions for tailoring fibre diameters were identified. Membranes having average fibre diameters—347, 738 and 1102nm were characterized, revealing average pore sizes of 800, 870 and 1060nm and pore volumes of 44%, 63% and 68% respectively. Hydrophobicity increased with increasing fibre diameter and porosity. Effective diffusion coefficients for glucose transport across the electrospun membranes varied as a function of thickness and porosity, indicating high flux rates for mass transport. Electrospun PU membranes having significantly high pore volumes, extensively interconnected porosity and tailorable properties compared to conventional solvent cast membranes can find applications as coatings for sensors requiring analyte exchange. [Copyright &y& Elsevier]