Biodegradable Waterborne Polyurethane Research Articles

General Semi-Solid Freeze Casting for Uniform Large-Scale Isotropic Porous Scaffolds: An Application for Extensive Oral Mucosal Reconstruction.

Ice-templated porous biomaterials possess transformative potential in regenerative medicine; yet, scaling up ice-templating processes for broader applications-owing to inconsistent pore formation-remains challenging. This study reports an innovative semi-solid freeze-casting technique that draws inspiration from semi-solid metal processing (SSMP) combined with ice cream-production routines. This versatile approach allows for the large-scale assembly of various materials, from polymers to inorganic particles, into isotropic 3D scaffolds featuring uniformly equiaxed pores throughout the centimeter scale. Through (cryo-)electron microscopy, X-ray tomography, and finite element modeling, the structural evolution of ice grains/pores is elucidated, demonstrating how the method increases the initial ice nucleus density by pre-fabricating a semi-frozen slurry, which facilitates a transition from columnar to equiaxed grain structures. For a practical demonstration, as-prepared scaffolds are integrated into a bilayer tissue patch using biodegradable waterborne polyurethane (WPU) for large-scale oral mucosal reconstruction in minipigs. Systematic analyses, including histology and RNA sequencing, prove that the patch modulates the healing process toward near-scarless mucosal remodeling via innate and adaptive immunomodulation and activation of pro-healing genes converging on matrix synthesis and epithelialization. This study not only advances the field of ice-templating fabrication but sets a promising precedent for scaffold-based large-scaletissue regeneration.

Porous Three-Dimensional Polyurethane Scaffolds Promote Scar-Free Endogenous Regeneration After Acute Brain Hemorrhage.

Intracerebral hemorrhage (ICH) is the most lethal subtype of stroke and is associated with significant morbidity and mortality. Despite advances in the clinical treatment of ICH, limited progress has been made regarding endogenous brain regeneration after ICH. Failure of brain regeneration is mainly attributed to the inhibitive regenerative microenvironment caused by secondary injury after ICH. In this study, we investigated a three-dimensional biodegradable waterborne polyurethane (BWPU) scaffold as a tool to promote brain regeneration after ICH. After implantation into the cavity following hematoma evacuation, these implanted scaffolds could act as a reservoir; store a series of necrotic debris, cytokines, and chemokines; and attract microglia/macrophages to their pores. Subsequently, these microglia/macrophages were polarized into the M1-like subtype to eliminate these substances. This process disperses M1-like immune cells and prevents the formation of dense glial scar-free structures after ICH. Inflammatory cells in scaffolds include scar-free secreted growth factors and extracellular matrix (ECM) proteins, and further induce a M2-like immune cells enriched regeneration-predominant microenvironment to promote endogenous brain regeneration with functional recovery. In summary, in this work, we have revealed the potential and mechanism of the BWPU scaffold as a tool to promote endogenous brain tissue regeneration after ICH.

Synthesis and properties of biodegradable waterborne polyurethane modified as castor oil

A series of biodegradable waterborne polyurethane (WPU) based on polycaprolactone diol and castor oil is synthesized through the process of the polyaddition reaction. Biodegradable WPUs are designed by using polycaprolactone diol and 4,4′- methylene dicyclohexyl diisocyanate as the main domain of urethane, dimethylol butanoic acid as the anionic internal emulsifier and trimethylamine as the neutralizing agent. Castor oil is introduced as a key component to induce or maximize the biodegradability and biocompatibility of a WPU series. The biodegradable ability of WPUs are changed by the control of Castor oil content and molecular weight (MW). The biodegradation of a WPU series prepared in this study is analyzed in field emission scanning electron microscopy through visual modifications in bio-enzyme evaluation. The effects of Castor oil and MW on the physical properties are evaluated using gel permeation chromatography (GPC), universal test machine (UTM), dynamic light scattering (DLS), differential scanning calorimetry (DSC), and field emission scanning electron microscopy (FE-SEM). The WPU with high level of MW and Castor oil shows enough enhancement in tensile strength and Young's modulus, ranging from 12.28 to 23.47 MPa and from 0.04 to 0.137 MPa, respectively. SEM results point to a significant microphase biodegradation of a WPU series by bio-enzymes. It can be an environmental-friendly candidate to apply various biofields.

A new UV‐curable biodegradable waterborne polyurethane‐acrylate based on natural rubber blended with cassava starch

AbstractAn ecofriendly UV‐curable biodegradable waterborne polyurethane acrylate (WPUA) was synthesized using hydroxy telechelic natural rubber (HTNR), gelatinized cassava starch (GCS) hexamethylene diisocyanate, hydroxymethyl propionic acid and 2‐hydroxyethyl acrylate and Darocur 1173 (photo‐initiator) for coating, adhesive applications, and so forth. WPUA thus prepared with a total solid content of about 20% had a good storage stability with a pot‐life of 3 months. The UV‐curable WPUA/GCS films showed superior photosensitivity with an irradiation time of 60 s. With increasing GCS content of the WPUA/GCS films, its transparency increased and surface gloss decreased. Scanning electron microscopic micrographs indicated good miscibility with strong interactions between WPUA and GSC in the matrix leading to high tensile strength and surface free energy with enhanced thermal degradation. Increasing the GCS content up to 75 wt% in the film accelerated its degradation under weathering aging, and showed complete disintegration in soil after 7 days. This work provided a new environmentally friendly pathway to prepare WPUA based on HTNR and GCS with good biodegradability.

Electroactive scaffolds of biodegradable polyurethane/polydopamine-functionalized graphene oxide regulating the inflammatory response and revitalizing the axonal growth cone for peripheral nerve regeneration.

Long-gap peripheral nerve injury remains a major challenge in regenerative medicine and results in permanent sensory and motor dysfunction. Nerve guidance scaffolds (NGSs) are known as a promising alternative to autologous nerve grafting. The latter, the current "gold standard" in clinical practice, is frequently constrained by the limited availability of sources and the inevitable damage to the donor area. Given the electrophysiological properties of nerves, electroactive biomaterials are being intensively investigated in nerve tissue engineering. In this study, we engineered a conductive NGS compounded of biodegradable waterborne polyurethane (WPU) and polydopamine-reduced graphene oxide (pGO) for repairing impaired peripheral nerves. The incorporation of pGO at the optimal concentration (3 wt%) promoted in vitro spreading of Schwann cells (SCs) with high expression of the proliferation marker S100 protein. In an in vivo study of sciatic nerve transection injury, WPU/pGO NGSs were found to regulate the immune microenvironment by activating macrophage M2 polarization and upregulate growth-associated protein 43 (GAP43) to facilitate axonal elongation. Histological and motor function analysis demonstrated that WPU/pGO NGSs had a neuroprosthetic effect close to that of an autograft, which significantly promoted the regeneration of myelinated axons, reduced gastrocnemius atrophy, and enhanced hindlimb motor function. These findings together suggested that electroactive WPU/pGO NGSs may represent a safe and effective strategy to manage large nerve defects.

Scarless Healing of Injured Vocal Folds Using an Injectable Hyaluronic Acid-Waterborne Polyurethane Hybrid Hydrogel to Tune Inflammation and Collagen Deposition.

Vocal fold (VF) scarring results from injury to the unique layered structure and is one of the main reasons for long-lasting dysphonia. A minimally invasive procedure with injectable hydrogels is a promising method for therapy. However, current surgical techniques or standard injectable fillers do not yield satisfactory outcomes. In this work, an injectable hybrid hydrogel consisting of oxide hyaluronic acid and hydrazide-modified waterborne polyurethane emulsion was injected precisely into the injury site and cross-linked in situ by a dynamic hydrazone bond. The prepared hydrogel displays excellent injectability and self-healing ability, showing favorable biocompatibility and biodegradability to facilitate endogenous newborn cell migration and growth for tissue regeneration. With the aim of evaluating the antifibrosis and regeneration capacity of the hybrid hydrogel in the VF scarring model, the morphology and vibration characteristics of VFs, inflammatory response, and healing status were collected. The hybrid hydrogel can decrease the inflammation and increase the ratio of collagen III/collagen I to heal damaged scar-free tissue. Fascinatingly, the mucosal wave oscillations of healing VF by injecting the hybrid hydrogel were vibrated like the normal VF, achieving functional restoration. This work highlights the utility of hybrid hydrogels consisting of synthetic biodegradable waterborne polyurethane emulsions and natural hyaluronic acid as promising biomaterials for scarless healing of damaged VFs.

Preparation and Characterization of Glucose and Sulfamate Double‐Modified Biodegradable Waterborne Polyurethane

AbstractA kind of glucose and sulfamate double‐modified waterborne polyurethane (WPU) was synthesized by using glucose (GLC) and N‐[(2‐amionoethyl)‐amino] ethane sulphonated sodium (AAS) as internal crosslinking agent, polycaprolactone glycol (PCL) as soft segment, 2,2‐bis(hydroxymethyl) propionic acid (DMPA) and N‐[(2‐amionoethyl)‐amino] ethane sulphonated sodium (AAS) as hydrophilic monomers. The influences of AAS and GLC content on the WPU structure and properties were analyzed and characterized by high speed of centrifugation, particle size examination, ATR‐FTIR, TEM, DMA, TGA, SEM, tensile tests, contact angle, water uptake and degradation measurements. The test results indicated that the modified biodegradable WPU had great comprehensive properties. Compared with the unmodified polyurethane, the prepared cross‐linked WPU had a good stability (over 6 months), outstanding mechanical strength (51.55 MPa for WPU4 films) and biodegradability (the weight loss in soil and PBS/lipase reached 25.2 % and 11.8 % for 6 weeks), which made them appropriate supplements for the traditional waterborne polyurethanes in the future.

Development of FGF-2-loaded electrospun waterborne polyurethane fibrous membranes for bone regeneration.

Guided bone regeneration (GBR) membrane has been used to improve functional outcomes for periodontal regeneration. However, few studies have focused on the biomimetic membrane mimicking the vascularization of the periodontal membrane. This study aimed to fabricate waterborne polyurethane (WPU) fibrous membranes loaded fibroblast growth factor-2 (FGF-2) via emulsion electrospinning, which can promote regeneration of periodontal tissue via the vascularization of the biomimetic GBR membrane. A biodegradable WPU was synthesized by using lysine and dimethylpropionic acid as chain extenders according to the rule of green chemical synthesis technology. The WPU fibers with FGF-2 was fabricated via emulsion electrospinning. The results confirmed that controlled properties of the fibrous membrane had been achieved with controlled degradation, suitable mechanical properties and sustained release of the factor. The immunohistochemical expression of angiogenic-related factors was positive, meaning that FGF-2 loaded in fibers can significantly promote cell vascularization. The fiber scaffold loaded FGF-2 has the potential to be used as a functional GBR membrane to promote the formation of extraosseous blood vessels during periodontal repairing.

A novel waterborne polyurethane with biodegradability and high flexibility for 3D printing

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.

A Highly Stretchable Microsupercapacitor Using Laser‐Induced Graphene/NiO/Co3O4 Electrodes on a Biodegradable Waterborne Polyurethane Substrate

AbstractConstructing microsupercapacitors (MSCs) with an outstanding stretchability is urgent for wearable electronics, and an intrinsic biodegradability is also meaningful. Herein, laser‐induced graphene/NiO/Co3O4 (NiO/Co3O4/LIG) is in situ synthesized on a polyimide (PI) film during laser processing, then the electrodes are transferred to a biodegradable waterborne polyurethane (WPU) substrate to fabricate stretchable MSCs. Experimentally, the as‐prepared stretchable MSCs exhibit an excellent areal capacitance of 2.4 mF cm−2, high capacitance retention of 77.1% at 50% strain, and capacitance degradation of less than 19.8% after 1000 stretching cycles. These desirable properties are mainly attributed to the gradient structure of NiO/Co3O4/LIG, the synergistic effect of hybrid NiO/Co3O4 nanoparticles, and the intensive interface adhesion between the electrodes and WPU. Interestingly, the robust function of stretchable MSCs is further presented by using them to power a microsensor and assembling them with triboelectric nanogenerators to generate power from mechanical contact with skin, which makes the stretchable MSCs promising as a sustainable driving source for wearable electronics.

Synthetic scheme to improve the solid content of biodegradable waterborne polyurethane by changing the association relationships of hydrophilic fragments.

A synthetic method was developed to prepare biodegradable waterborne polyurethanes (BHPUs) with a high solid content by introducing different molecular weights of poly(ethylene glycol) (PEG) into poly(ε-caprolactone) (PCL)-based polyurethanes. PCL is a semi-crystalline polymer that can be degraded in lipase to prepare biodegradable waterborne polyurethanes. The biodegradability of BHPUs was evaluated, and the results showed that BHPU samples could be degraded in a solution of phosphate-buffered saline (PBS)/lipase but not in PBS. Two different synthesis routes were used to prepare the BHPUs, which resulted in different association relationships between the ionic hydrophilic polymer dimethylol propionic acid (DMPA) and a nonionic hydrophilic polymer (PEG). The influence of the association relationship between DMPA and PEG on the solid content and other BHPU properties was investigated. The results showed that the method of associating all PEG molecules with DMPA increased the crystallization, tensile properties, and water and soil repellency of the BHPU samples. The solid content of the BHPU samples increased from 41% to 52.7%. In addition, PEG with molecular weights of 400 g mol−1 and 1000 g mol−1 had the best effect on the dispersibility and stability of BHPU samples when incorporated into a polyurethane backbone.

Effects of soft segment characteristics on the properties of biodegradable amphiphilic waterborne polyurethane prepared by a green process

Traditional 3D printing materials are not suitable for tissue engineering due to their toxicity, low degradability and poor biocompatibility. In this study, a new amphiphilic biodegradable waterborne polyurethane (WBPU) was developed by a green and sustainable process without any organic solvents, catalysts or cross-linkers. The soft segments of this kind of WBPU were formed by replacing hydrophobic poly(e-caprolactone) diol with hydrophilic poly(ethylene glycol) (PEG). Different block lengths of PEG were used for this purpose. The combination of ester and ether groups endowed WBPU with amphiphilic characteristics, which is important for regeneration and maintenance of tissue. The effects of composition and content of soft segments on the phase separation, thermal properties, mechanical properties, water absorption, biodegradability and cytotoxicity of WBPU were investigated. The results showed that the desired properties of WBPU could be achieved by tuning the block length of PEG and content of soft segments. The present work provided a new approach to prepare WBPUs with amphiphilic and biodegradable characteristics, which are promising candidates for 3D printing materials for tissue engineering scaffolds.

Aligned 3D porous polyurethane scaffolds for biological anisotropic tissue regeneration.

A green fabrication process (organic solvent-free) of artificial scaffolds is required in tissue engineering field. In this work, a series of aligned three-dimensional (3D) scaffolds are made from biodegradable waterborne polyurethane (PU) emulsion via directional freeze–drying method to ensure no organic byproducts. After optimizing the concentration of polymer in the emulsion and investigating different freezing temperatures, an aligned PUs scaffold (PU14) generated from 14 wt% polymer content and processed at −196°C was selected based on the desired oriented porous structure (pore size of 32.5 ± 9.3 μm, porosity of 92%) and balanced mechanical properties both in the horizontal direction (strength of 41.3 kPa, modulus of 72.3 kPa) and in the vertical direction (strength of 45.5 kPa, modulus of 139.3 kPa). The response of L929 cells and the regeneration of muscle tissue demonstrated that such pure material-based aligned 3D scaffold can facilitate the development of orientated cells and anisotropic tissue regeneration both in vitro and in vivo. Thus, these pure material-based scaffolds with ordered architecture have great potentials in tissue engineering for biological anisotropic tissue regeneration, such as muscle, nerve, spinal cord and so on.

Biodegradable waterborne polyurethane grafted with gelatin hydrolysate via solvent-free copolymerization for potential porous scaffold material

One potential porous scaffold material based on polyester waterborne polyurethane (PEUR) grafted with modified gelatin hydrolysate (GH) has been investigated in this research. First, the GH was modified with a silane coupling agent (KH550), and then the modified GH was mixed with pre-polymer emulsion of PEUR to obtain the PEUR grafted GH emulsion (PEUR-g-GH). The synthesized PEUR-g-GH emulsions were characterized by stability analysis and viscosity test. Moreover, the film-forming property of PEUR-g-GH has also been studied, and the PEUR-g-GH films were characterized regarding the water resistance, solvent resistance, mechanical properties, FTIR, AFM, SEM, DMA, TGA and contact angle testing. Finally, the bioactivity and biodegradation were investigated by soaking PEUR-g-GH scaffolds in simulated body fluid (SBF). The results indicated that the PEUR-g-GH emulsion has good stability, water resisting (the contact angle was over 90o), the PEUR-g-GH showed excellent film-forming, high storage modulus, good structural homogeneity and thermal stability (the temperature of maximum weight loss was over 350 °C). The freeze-dried sample showed porous structure, and the mutual crosslinking of layers can contribute to a good bearing capacity for scaffold. The SBF biodegradability revealed that the biodegradation rate and degree of films gradually increased with the content of GH increased. In addition, the cells on the material were markedly enhanced, and most of cells have proliferated and formed vesicles, which shown a good biocompatibility.

Modulating the burst drug release effect of waterborne polyurethane matrix by modifying with polymethylmethacrylate

ABSTRACTTo reduce cost and increase environmental friendliness, waterborne polyurethane (WPU) is a tempting choice in the field of green chemistry. Biodegradable WPU was synthesized using lysine as an internal emulsifier. WPU was further modified using methylate methacrylate (MMA) as an acrylic monomer. Unsaturated pre‐PU was synthesized by using unsaturated end‐capping agent 2‐hydroxyethyl methacrylate and further extended by MMA to form acrylate modified WPU. A permanent covalent linkage was established between WPU and PMMA as confirmed by FTIR spectroscopy. The focus of this research work was to study the dependence of drug delivery, mechanical, thermal, surface, and structural properties of WPU, on the MMA repeating unit content (10%–40%). For drug release studies mitomycin c was taken as a model anticancer drug. Furthermore, these materials were subjected to in vitro and in vivo cytotoxicity evaluation, which shows that synthesized acrylate modified WPU are biocompatible. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47253.

Biodegradable waterborne polyurethane with modified hydroxyethylcellulose

Biodegradable waterborne polyurethane with modified hydroxyethylcellulose

Preparation and evaluation of a novel sunflower oil‐based waterborne polyurethane nanoparticles for sustained delivery of hydrophobic drug

In the present study, a nanoparticulate system based on bio‐based waterborne polyurethane for the controlled delivery of raloxifene‐hydrochloride, as a model and drug with poor bioavailability, is described and considered to be an antiproliferative agent of mammary tissue. The main goal of this study was to investigate the effect of the encapsulation of raloxifene in bio‐based polyurethane, synthesized for the first time, as a polymer with anionic surface on the release profile as well as antiproliferative activity. Polyurethane was synthesized from bio‐based polyol, which was derived from sunflower oil. The structure of bio‐based polyurethane was characterized using 1HNMR, FT‐IR, and TGA. Drug release studies showed controlled release of raloxifene from anionic nanoparticles that was mainly driven by diffusion‐based mechanism. Degradation of nanoparticles during the release of Ral was investigated applying SEM and caused mainly through the hydrolysis of polyurethane. MCF‐7 cell viability studies demonstrated that, raloxifene loaded nanoparticles promote the antiproliferative activity after 72 h of treatment. The bio‐based polyurethane has potential as a useful carrier for controlled release of hydrophobic drugs.Practical applications: A novel carboxylic acid group containing polyol was prepared from sunflower oil and used in preparation of biodegradable waterborne polyurethane. The synthesized waterborne polyurethane was loaded by drug and its loading capacity was studied. Drug release studies showed controlled release of raloxifene from anionic nanoparticles that was mainly driven by diffusion‐based mechanism. Cell viability studies demonstrated that raloxifene loaded nanoparticles promote the antiproliferative activity.A novel carboxylic acid group containing polyol was prepared from sunflower oil and used in preparation of biodegradable waterborne polyurethane. The synthesized waterborne polyurethane was loaded by drug and its loading capacity was studied. Drug release studies showed controlled release of raloxifene from anionic nanoparticles that was mainly driven by diffusion‐based mechanism. Cell viability studies demonstrated that raloxifene loaded nanoparticles promote the antiproliferative activity.

Nanofibrous scaffold from electrospinning biodegradable waterborne polyurethane/poly(vinyl alcohol) for tissue engineering application

A series of nanofibrous scaffolds, free of organic solvents, are prepared by electrospinning biodegradable waterborne polyurethane (BWPU) emulsion blending with aqueous poly(vinyl alcohol)(PVA). Tuning the proration of BWPU to PVA, various nanofibers with diameter from 370 to 964 nm are obtained. Strong intermolecular interaction existing between them benefits to the electrospun of BWPU emulsion, which is demonstrated by dynamic thermomechanical analysis and Fourier transform infrared spectroscopy. The nontoxic nanofibrous scaffolds with porous structure, which is similar to the natural extracellular matrix, favor to the attachment and proliferation of the L929 fibroblasts. Thus, the scaffolds are promising to be used as biomaterials for many natural tissues repair.

Biodegradable waterborne polyurethane to fabricate scaffold for soft tissue engineering

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Stability of biodegradable waterborne polyurethane films in buffered saline solutions.

The stability of polyurethane (PU) is of critical importance for applications such as in coating industry or as biomaterials. To eliminate the environmental concerns on the synthesis of PU which involves the use of organic solvents, the aqueous-based or waterborne PU (WBPU) has been developed. WBPU, however, may be unstable in an electrolyte-rich environment. In this study, the authors reported the stability of biodegradable WBPU in the buffered saline solutions evaluated by atomic force microscopy (AFM). Various biodegradable WBPU films were prepared by spin coating on coverslip glass, with a thickness of ∼300 nm. The surface AFM images of poly(ε-caprolactone) (PCL) diol-based WBPU revealed nanoglobular structure. The same feature was observed when 20% molar of the PCL diol soft segment was replaced by polyethylene butylenes adipate diol. After hydration in buffered saline solutions for 24 h, the surface domains generally increased in sizes and became irregular in shape. On the other hand, when the soft segment was replaced by 20% poly(l-lactide) diol, a meshlike surface structure was demonstrated by AFM. When the latter WBPU was hydrated, the surface domains appeared to be disconnected. Results from the attenuated total reflectance infrared spectroscopy and x-ray photoelectron spectroscopy indicated that the surface chemistry of WBPU films was altered after hydration. These changes were probably associated with the neutralization of carboxylate by ions in the saline solutions, resulting in the rearrangements of soft and hard segments and causing instability of the WBPU.