Characterization of a biodegradable electrospun polyurethane nanofiber scaffold: Mechanical properties and cytotoxicity (original) (raw)
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Tissue Engineering Part A, 2014
Electrospinning technology is an attractive process for the fabrication of a scaffold with an annulus fibrosus (AF)-like architecture for tissue engineering. Oriented and nonoriented electrospun scaffolds were prepared from poly(ester-urethane) (PU) and poly(e-caprolactone) (PCL) as well as corresponding homogeneous films. Scaffolds' characteristics and mechanical properties were characterized by scanning electron microscopy, static water contact measurements, and dynamic mechanical analysis, respectively. The effect of scaffold architecture and polymer composition on bovine AF cells was investigated. PU and PCL films and scaffolds supported AF cell growth and extracellular matrix production and accumulation. Electrospun scaffolds increased the retention of collagen and glycosaminoglycan compared with films. Fiber orientation of the scaffolds promoted the AF cell phenotype with a trend toward an upregulation of matrix gene expression for oriented relative to nonoriented scaffolds. The higher yield strain of an oriented electrospun PU scaffold, compared with other scaffolds, will be advantageous for AF tissue engineering under a dynamic mechanical environment.
Biodegradable polyurethanes: Comparative study of electrospun scaffolds and films
Journal of Applied Polymer Science, 2011
The development of elastomeric, bioresorbable, and biocompatible segmented polyurethanes (SPUs) for use in tissue-engineering applications has attracted considerable interest in recent years. In this work, nonporous films and microfiber/nanofiber scaffolds, which were prepared from two different poly(e-caprolactone)-based SPUs previously synthesized from 1,6-hexamethylene diisocyanate and novel chain extenders containing urea groups or an aromatic amino acid derivative, were studied. Their thermal properties were influenced by both the different chemical structures of the hard segments and the processing conditions. The mechanical properties of the scaffolds (the elastic modulus, ultimate strain, and tensile stress) were adequate for engineered soft-tissue constructs (e.g., myocardial tissue). The film samples displayed a low swelling degree (<2 wt %) in a phosphatebuffered solution at 37 C. The introduction of the amino acid derivative chain extender with hydrolyzable ester bonds contributed to greater degradation. The fibrous scaffolds exhibited higher hydrolytic stability than the films after short assay times because of their more crystalline structures and higher degrees of association by hydrogen bonding, but they also experienced higher mass losses under accelerated conditions (70 C). This suggested that the degradation rate was not constant but depended on the degradation time and the processing technique. V
Journal of Biomedical Materials Research Part A, 2007
The purpose of this research was to develop and characterize a novel, slowly degrading polyesterurethane. In this study, a polyesterurethane with a crystalline segment of poly((R)-3-hydroxybutyric acid)-diol linked by a diisocyanate to an amorphous segment of poly(e-caprolactone-co-glycolide)-diol was synthesized. Porous and nonporous scaffolds were processed using electrospinning and solvent casting respectively. The morphology, pore size, and filament diameter of the mesh and film were characterized using scanning electron microscopy (SEM). The thermal properties were examined using differential scanning calorimetry (DSC). A degradation study was initiated to characterize the change in mechanical properties, molecular weight, and surface morphology over 12 months using tensile testing, gel permeation chromatography (GPC), and SEM respectively. Concomi-tantly, cell morphology and viability on these variants were investigated using fibroblasts. The mechanical test data indicated a gradual decrease in the ultimate tensile strength and strain to break while the modulus of elasticity remained stable. GPC data suggested a slow decrease in the molecular weight while SEM examination revealed changed surface morphologies. The in vitro studies implied that the novel polyesterurethane was not cytotoxic and that the mesh was a more favorable scaffold towards cell viability. The summation of these results suggests that this polyesterurethane has the potential for tissue engineering applications.
Biomaterials, 2011
Tissue engineering of the annulus fibrosus(AF), a component of the intervertebral disc, has proven to be challenging due to its complex oriented lamellar structure. Previously it was demonstrated that polyurethane (PU) scaffolds containing an anionic dihydroxy oligomers (ADO) may be suitable to use in this application. The current study examines whether matrix protein(s) coatings (collagen type I, collagen type I and fibronectin, fibronectin, or vitronectin) would promote cell and collagen orientation that more closely mimics native AF. The greatest cell attachment occurred when scaffolds were pre-coated with Fn. Cells on Fn-coated scaffolds were aligned parallel to scaffold fibers, a process that involved a5b1 integrin, as determined by integrin-specific blocking antibodies, which in turn reduced AF cell spreading and alignment. Cell shape was regulated by the actin cytoskeleton as cells grown in the presence of cytochalasin D did not spread. Cells on Fn-coated PU scaffolds formed fibrillar Fn, synthesized significantly more collagen, and showed linear alignment of the secreted type I collagen when compared to cells grown on the other protein-coated scaffolds and the non-coated control. Thus Fn-coating of PUeADO scaffolds appears to promote properly oriented AF cells and collagen, which should facilitate developing AF tissue that more closely mimics the native tissue.
Biodegradable polymers applied in tissue engineering research: a review
Polymer International, 2007
Typical applications and research areas of polymeric biomaterials include tissue replacement, tissue augmentation, tissue support, and drug delivery. In many cases the body needs only the temporary presence of a device/biomaterial, in which instance biodegradable and certain partially biodegradable polymeric materials are better alternatives than biostable ones. Recent treatment concepts based on scaffold-based tissue engineering principles differ from standard tissue replacement and drug therapies as the engineered tissue aims not only to repair but also regenerate the target tissue. Cells have been cultured outside the body for many years; however, it has only recently become possible for scientists and engineers to grow complex three-dimensional tissue grafts to meet clinical needs. New generations of scaffolds based on synthetic and natural polymers are being developed and evaluated at a rapid pace, aimed at mimicking the structural characteristics of natural extracellular matrix. This review focuses on scaffolds made of more recently developed synthetic polymers for tissue engineering applications. Currently, the design and fabrication of biodegradable synthetic scaffolds is driven by four material categories: (i) common clinically established polymers, including polyglycolide, polylactides, polycaprolactone; (ii) novel di-and tri-block polymers; (iii) newly synthesized or studied polymeric biomaterials, such as polyorthoester, polyanhydrides, polyhydroxyalkanoate, polypyrroles, poly(ether ester amide)s, elastic shape-memory polymers; and (iv) biomimetic materials, supramolecular polymers formed by self-assembly, and matrices presenting distinctive or a variety of biochemical cues. This paper aims to review the latest developments from a scaffold material perspective, mainly pertaining to categories (ii) and (iii) listed above.
Polymer Degradation and Stability, 2003
Morphology and the biomechanical properties of the fibrous nonwoven poly (glycolic acid) (PGA) scaffolds were studied over 8 weeks of in vitro degradation. Morphology of the PGA scaffold was examined using scanning electron microscopy (SEM). Results showed that at day 3 to day 14, the fibers in the scaffolds became more separated apparently due to the initial swelling effect of medium absorption. However, the samples shrank dimensionally by day 28 and some became disintegrated shortly afterwards. More fiber endings could apparently be found in samples with longer periods of degradation. As degradation time increased, some fiber end surfaces showed signs of further decays. During the degradation period, there were little changes in the chemical structures as determined by Fourier Transform Infrared Spectroscopy. Thermal studies by differential scanning calorimetry (DSC) showed that the melting temperatures of the scaffold material shifted lower, while the degree of crystallinity determined by both DSC and X-ray diffraction increased significantly during the initial degradation period and apparently decreased afterwards. Biomechanical tests of 10% compression and 14% shear were performed to study the structural properties of the scaffolds upon degradation. The results clearly showed that the fibrous non-woven PGA scaffolds lost their structural properties substantially over relatively short period of in-vitro degradation. Whether such a degradation speed is optimal or not should be carefully evaluated for different tissue engineering applications.
European Polymer Journal, 2015
Polymeric elastomers like Poly(1,3-diamino-2-hydroxypropane-co-polyol sebacate) (APS) have gained importance in soft tissue engineering applications due to their tunable mechanical properties and biodegradability. The fabrication of extracellular matrix (ECM)-mimetic nanofibrous scaffolds using APS is however limited due to its poor solubility in commonly used solvents, low viscosity and high temperatures required for thermal curing. In this study, we have overcome these limitations of APS by blending uncrosslinked APS pre-polymer with polycaprolactone (PCL), and have successfully fabricated ECMmimetic nanofibrous APS scaffolds for the first time. The developed fibrous scaffolds were further characterized for their physicochemical, thermal, mechanical and degradation properties. Effects of APS:PCL weight ratios (0:1, 1:1, 2:1 and 4:1) and total polymer concentration (15-30% w/v) on the fiber morphology, tensile properties, chemical and thermal properties of the APS-PCL composite scaffolds were investigated. Higher APS concentrations in the polymer blend resulted in formation of fused fibers and thus, increased fiber diameters. The degree of hydration and consequently, degradation rate of the scaffolds increased with the APS concentration. The FTIR and DSC studies showed selective loss of APS polymer from composite scaffolds after degradation. Scaffolds with 1:1 APS:PCL ratio exhibited maximum elastic modulus (EM) of 30 ± 2.5 MPa compared to 0:1, 2:1 and 4:1 ratios. Increasing total polymer concentrations (15-30% w/v) at constant (2:1) APS:PCL ratio increased stiffness and tensile strength of the electrospun scaffolds. Biocompatibility studies using C2C12 mouse myoblast cells showed enhanced cell spreading on APS containing scaffolds after 6 h as compared to PCL-only scaffolds. Thus, the present study demonstrates successful development of APS-based thermoset elastomeric nanofibrous scaffolds by blending with semicrystalline PCL polymer for the first time. Tunable physicochemical, mechanical and degradation properties of these composite APS-PCL scaffolds will be further exploited for skeletal muscle tissue engineering applications.
Biodegradable and biocompatible polymers for tissue engineering application: a review
Artificial cells, nanomedicine, and biotechnology, 2016
Since so many years ago, tissue damages that are caused owing to various reasons attract scientists' attention to find a practical way to treat. In this regard, many studies were conducted. Nano scientists also suggested some ways and the newest one is called tissue engineering. They use biodegradable polymers in order to replace damaged structures in tissues to make it practical. Biodegradable polymers are dominant scaffolding materials in tissue engineering field. In this review, we explained about biodegradable polymers and their application as scaffolds.
Recent concepts in biodegradable polymers for tissue engineering paradigms: a critical review
International Materials Reviews, 2018
Tissue engineering and regenerative medicine are emerging as future approaches for the treatment of acute and chronic diseases. However, many challenging clinical conditions exist today and include congenital disorders, trauma, infection, inflammation and cancer, in which hard and soft tissue damage, organ failure and loss are still not treated effectively. Regenerative medicine has contributed to a number of innovations through artificial implants and biomedical materials, with advances are continually being made. Researchers are constantly developing new biomaterials and tissue engineered technologies to stimulate tissue regeneration in order to repair and replace damaged or malfunctioning organs. However, the challenge continues to lie in devising effective biomedical materials that can be implanted as scaffolds. Various approaches are emerging, according to the organ, tissue, disease and disorder. Scaffolds are implanted cell-free, or incorporated with stems cells, committed cells, or bioactive molecules. Irrespective, engineered biomaterials are required to regenerate and ultimately reproduce the original physiological, biological, chemical and mechanical properties over time. This is enabled by providing a three-dimensional architecture for cells to adhere, migrate, proliferate within, and differentiate appropriately for the growth of new tissues to provide a relevant structure, and in so doing, restore function. Biodegradable materials have been used extensively as regenerative therapies since their advent in early 20th century. One notable example is the development of surgical fixation devices. The selection, design and physicochemical properties of these materials are important and must consider biocompatibility, biodegradability and minimal cytotoxicity in the host to enable cell-proliferation, cell-matrix interactions and intercellular signalling for stimulating tissue growth. In this review, we critique the most studied and recently developed biodegradable