Biodegradable Poly Ester Urethane Research Articles

Fabrication of biodegradable polyurethane electrospun webs of fibers modified with biocompatible graphene oxide nanofiller

A successful optimization of the electrospinning parameters for obtainment of biodegradable polyester urethane (DP) webs of fibers, neat and graphene oxide (GO) modified, was performed. The effect of the processing parameters (distance between the needle tip and the collector, applied voltage, and flowing rate), solution type and polymer concentration, on the fiber-forming process and the obtained fibers’ morphology was examined. The best homogeneity of the fibers was achieved for 12 wt% DP dissolved in 80:20 wt% mixture of chloroform and ethanol, applying similar processing parameters for the neat and modified samples (0.5 ml/h pumping rate, 15 kV applied voltage, and 150 mm distance to the collector, for the neat sample, and 0.4 ml/h, 18 kV, and 110 mm, for the GO modified samples). The main novelty of this work is the modification of DP with low quantities (0.5, 1.0 and 2.0 wt%) of GO – the “next generation” nanomaterial for stem cell control. The morphological characterization revealed a fibrous microstructure consisting of randomly oriented fibers with a diameters ranging from hundreds nanometers to couple micrometers, representing a feasible imitation of the structure of extracellular matrix (ECM). The XRD studies showed high dispersion of GO in DP matrix and even exfoliation for the sample that contains 2 wt% GO. Raman studies neatly complemented the highest filler/matrix interactions and the superior levels of dispersion for this sample. TGA was used to analyze the thermo-oxidative degradation and also to determine the actual content of GO present in the samples.

Poly(caprolactone-co-trimethylenecarbonate) urethane acrylate resins for digital light processing of bioresorbable tissue engineering implants.

To exploit the usability of Digital Light Processing (DLP) in regenerative medicine, biodegradable, mechanically customizable and well-defined polyester urethane acrylate resins were synthesized based on poly(caprolactone-co-trimethlenecarbonate). By controlling the monomer ratio, the resultant fabricated constructs showed tunable mechanical properties, degradation and attached hMSC morphologies.

Elektropredenje biorazgradljivega poliester- uretana: vpliv prevodnosti raztopine polimera

Elektropredenje biorazgradljivega poliester- uretana: vpliv prevodnosti raztopine polimera

Biodegradable polyester-urethane bilayered systems for wound healing. An in vitro / in vivo correlation for dressings based on hydrophilic and amphiphilic systems

Biodegradable polyester-urethane bilayered systems for wound healing. An in vitro / in vivo correlation for dressings based on hydrophilic and amphiphilic systems

Comparative evaluation of novel biodegradable nanoparticles for the drug targeting to breast cancer cells

Nanomedicine formulations such as biodegradable nanoparticles (nps) and liposomes offer several advantages over traditional routes of administration: due to their small size, nanocarriers are able to selectively accumulate inside tumours or inflammatory tissues, resulting in improved drug efficacy and reduced side effects. To further augment targeting ability of nanoparticles towards tumour cells, specific ligands or antibodies that selectively recognise biomarkers over-expressed on cancer cells, can be attached to the surface either by chemical bond or by hydrophilic/hydrophobic interactions. In the present work, Herceptin (HER), a monoclonal antibody (mAb) able to selectively recognise HER-2 over-expressing tumour cells (such as breast and ovarian cancer cells), was absorbed on the surface of nanoparticles through hydrophilic/hydrophobic interactions. Nps were prepared by a modified single emulsion solvent evaporation method with five different polymers: three commercial polyesters (poly(ε-caprolactone) (PCL), poly (d,l-lactide) (PLA) and poly (d,l-lactide-co-.glycolide) (PLGA)) and two novel biodegradable polyesterurethanes (PURs) based on Poly(ε-caprolactone) blocks, synthesised with different chain extenders (1,4-cyclohexane dimethanol (CDM) and N-Boc-serinol). Polyurethanes were introduced as matrix-forming materials for nanoparticles due to their high chemical versatility, which allows tailoring of the materials final properties by properly selecting the reagents. All nps exhibited a small size and negative surface charge, suitable for surface functionalisation with mAb through hydrophilic/hydrophobic interactions. The extent of cellular internalisation was tested on two different cell lines: MCF-7 and SK-BR-3 breast cancer cells showing a normal and a high expression of the HER-2 receptor, respectively. Paclitaxel, a model anti-neoplastic drug, was encapsulated inside all nps, and release profiles and cytotoxicity on SK-BR-3 cells were also assessed. Interestingly, PUR nps were superior to commercial polyester-based nps in terms of higher cellular internalisation and cytotoxic activity on the tested cell lines. Results obtained warrants further investigation on the application of these PUR nps for controlled drug delivery and targeting.

Effect of the solubility of antibiotics on their release from degradable polyurethane

Application of biodegradable polyester urethane, as a drug loading matrix in the form of a coating on implant devices was investigated. Polyester urethane films were loaded with model antibiotics, like rifampicin, gentamicin and ciprofloxacin and their release characteristics were evaluated in simulated body fluid. Effect of solubility of antibiotics and degradation of matrix on the drug release behavior of biodegradable polyester urethane coating was also studied. It was observed that antibiotics having hydrophilicity or lipophilicity same as that of polymer matrix provide an extended release with relatively less initial burst release. Effect of degradation of polymer matrix has a dual significance in this case and the drug release rate increases with the increase in degradation rate. A high initial burst release was observed for antibiotics having hydrophilicity or lipophilicity opposite to that of polyurethane matrix and hence in this case antibiotic release was not significantly controlled by degradation of matrix.

Drug release from biodegradable polyesterurethanes with shape-memory effect

Three dimension (3D) printing has been increasingly used to make tissue engineering scaffolds. However, polyester-based scaffolds made through traditional 3D printing such as fused deposition modeling (FDM) lack of bioactivity as biomolecules cannot be directly blended with inks to achieve an in situ delivery. In addition, with increasing demand of reducing surgical trauma, implanting scaffolds through a minimally invasive way is of great importance. Here, surface porous tissue engineering scaffolds were made from novel poly(D,L-lactic acid-co-trimethylene carbonate)-based water-in-oil emulsions through a cryogenic 3D plotting. The effects of water content in emulsions on the microstructure of 3D plotted scaffolds were investigated. With heat treatment at 40 °C, scaffolds became soft and can be injected into a catheter. Growth factors can be loaded into the scaffolds in situ and showed a sustained release within 30 days.

Biodegradable polyesterurethanes with shape-memory properties for dexamethasone and aspirin controlled release

Biodegradable polyesterurethanes with shape-memory properties for dexamethasone and aspirin controlled release

Biodegradable polyesterurethane networks for controlled release of aspirin

AbstractIn this article, poly(D,L‐lactide‐co‐glycolide)urethane (PULG) networks were prepared from hydroxyl telechelic star‐shaped oligo(D,L‐lactide‐co‐glycolide) coupled with 1,6‐diisocyanate‐2,2,4‐trimethylhexane and 1,6‐diisocyanate‐2,4,4‐trimethylhexane or isophorone diisocyanate. The release of model drug aspirin (ASP) from biodegradable polyesterurethane networks was studied in phosphate buffered saline pH = 7.0 at 37°C. PULG networks turned from transparent to opaque after ASP loading. PULG networks with lower crosslinking density always resulted in higher drug loaded content. The results of differential scanning calorimetry and scanning electron microscope measurements demonstrated that ASP was uniformly distributed in the networks. The drug release courses of ASP from PULG networks in phosphate buffered saline pH = 7.0 at 37°C could be divided into three stages. Firstly, ASP release was at approximately uniform rate from PULG networks; Secondly, the release rate obviously increased due to the degradation of the PULG networks; Thirdly, the release rate decreased gradually because most of the ASP had diffused out of the PULG networks. The crosslinking density of polyesterurethane networks also affected both degradation of the polymer networks and drug release rate. The in vitro release test revealed that ASP accelerated the degradation process of PULG, which exhibited a typical erosion‐controlled release mechanism. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Release of Aspirin from Biodegradable Polyesterurethane Networks

In this paper, the release of model drug aspirin (ASP) from biodegradable polyesterurethane networks was studied. Poly(D,L-lactide-co-glycolide)urethane (PULG) networks were prepared from hydroxyl telechelic star-shaped oligo(D,L-lactide-co-glycolide) coupled with 1,6-diisocyanate-2,2,4-trimethylhexane and 1,6-diisocyanate-2,4,4-trimethylhexane or isophorone diisocyanate. PULG networks turned from transparent to opaque after ASP loading. PULG networks with lower crosslinking density always resulted in higher drug loaded content. The results of differential scanning calorimetry (DSC) and scanning electron microscope (SEM) measurements demonstrated that ASP was uniformly distributed in the networks. The drug release courses of ASP from PULG networks in phosphate buffered saline pH = 7.0 at 37 °C could be divided into three stages. Firstly, ASP release was at approximately uniform rate from PULG networks; Secondly, the release rate obviously increased for the degradation of the PULG networks; Thirdly, the release rate decreased gradually because most of the ASP had diffused out of the PULG networks. The crosslinking density of polyesterurethane networks also affected drug release rate. The in vitro release test revealed that ASP accelerated the degradation process of PULG, which exhibited a typical erosion-controlled release mechanism.

Structural variants of biodegradable polyesterurethane in vivo evoke a cellular and angiogenic response that is dictated by architecture

The aim of this study was to investigate an in vivo tissue response to a biodegradable polyesterurethane, specifically the cellular and angiogenic response evoked by varying implant architectures in a subcutaneous rabbit implant model. A synthetic biodegradable polyesterurethane was synthesized and processed into three different configurations: a non-porous film, a porous mesh and a porous membrane. Glutaraldehyde cross-linked bovine pericardium was used as a control. Sterile polyesterurethane and control samples were implanted subcutaneously in six rabbits ( n = 12). The rabbits were killed at 21 and 63 days and the implant sites were sectioned and histologically stained using haemotoxylin and eosin (H&E), Masson’s trichrome, picosirius red and immunostain CD31. The tissue–implant interface thickness was measured from the H&E slides. Stereological techniques were used to quantify the tissue reaction at each time point that included volume fraction of inflammatory cells, fibroblasts, fibrocytes, collagen and the degree of vascularization. Stereological analysis inferred that porous scaffolds with regular topography are better tolerated in vivo compared to non-porous scaffolds, while increasing scaffold porosity promotes angiogenesis and cellular infiltration. The results suggest that this biodegradable polyesterurethane is better tolerated in vivo than the control and that structural variants of biodegradable polyesterurethane in vivo evoke a cellular and angiogenic response that is dictated by architecture.

In vitro degradation of a biodegradable polyurethane foam, based on 1,4‐butanediisocyanate: A three‐year study at physiological and elevated temperature

Biodegradable polyesterurethanes (PUs) may be used as scaffold materials for tissue regeneration applications, because of their excellent mechanical properties. In this study, the degradation of highly porous PU foams was evaluated in vitro. The PU had amorphous soft segments of DL-lactide/epsilon-caprolactone and uniform hard segments, synthesized from 1,4-butanediisocyanate and butanediol. The foams were degraded for 3 years in a Sörensen buffer solution (pH 7.4) at 37 and 60 degrees C. Dimensions of the foams, intrinsic viscosity, mass loss, thermal properties, and composition of the remaining material were evaluated. Copolyester (CP) foams of DL-lactide/epsilon-caprolactone served as controls. The PU foams kept their dimensions for 20 weeks at 37 degrees C, whereas CP foams collapsed after 3 weeks. PU mass loss reached a maximum of 80% at both 37 and 60 degrees C. CP mass loss reached 99.9% at 60 degrees , and 92% at 37 degrees C after 3 years. The degradation processes at 37 and 60 degrees C are initially the same, but eventually degradation products with different thermal properties are being formed. (1)H NMR studies showed that the hard urethane segments of the PU do not degrade in vitro at pH 7.4. It was concluded that the PU material has favorable characteristics for a scaffold material. Compared to long-term in vivo results of the same PU these in vitro results are not representative for the in vivo situation and therefore total resorption has to be investigated in long-term in vivo studies.

Sustained release of antibiotic from polyurethane coated implant materials

Implant associated infections are of increasing importance. To minimize the risks of implant-associated infections recent biomedical strategies have led to the modification of the medical device surfaces. The modifications are in the terms of increasing surface biocompatibility and decreasing bacterial adherence, which can be achieved by applying a coating of biocompatible polymer onto the said surfaces. Entrapping anti-infective agents in a polymer matrix provides an approach to kill bacteria and combat the possibility of any residual infection. We have prepared a biodegradable polyester urethane coat for implant materials, which have the property to accommodate antibiotics within itself. These polyurethane coating materials were characterized by FTIR spectroscopy, swelling property in SBF, gravimetric analysis, drug release, and biocompatibility study. Drug release rates, bacterial colonization and morphological features were also evaluated to predict and understand the antimicrobial activity of these delivery systems. Drug release characteristics were investigated and the physico-chemical mechanisms of the delivery were discussed. Results suggest that the polyester urethane can be used as an implant coating material and can be used as a matrix for the sustained delivery of anti-infective agent.

An Elastic, Biodegradable Cardiac Patch Induces Contractile Smooth Muscle and Improves Cardiac Remodeling and Function in Subacute Myocardial Infarction

Our objective in this study was to apply an elastic, biodegradable polyester urethane urea (PEUU) cardiac patch onto subacute infarcts and to examine the resulting cardiac ventricular remodeling and performance. Myocardial infarction induces loss of contractile mass and scar formation resulting in adverse left ventricular (LV) remodeling and subsequent severe dysfunction. Lewis rats underwent proximal left coronary ligation. Two weeks after coronary ligation, a 6-mm diameter microporous PEUU patch was implanted directly on the infarcted LV wall surface (PEUU patch group, n = 14). Sham surgery was performed as an infarction control (n = 12). The LV contractile function, regional myocardial wall compliance, and tissue histology were assessed 8 weeks after patch implantation. The end-diastolic LV cavity area (EDA) did not change, and the fractional area change (FAC) increased in the PEUU patch group (p < 0.05 vs. week 0), while EDA increased and FAC decreased in the infarction control group (p < 0.05). The PEUU patch was largely resorbed 8 weeks after implantation and the LV wall was thicker than infarction control (p < 0.05 vs. control group). Abundant smooth muscle bundles with mature contractile phenotype were found in the infarcted myocardium of the PEUU group. The myocardial compliance of the PEUU group was distributed between normal myocardium and infarction control (p < 0.001). Implantation of a novel biodegradable PEUU patch onto a subacute myocardial infarction promoted contractile phenotype smooth muscle tissue formation and improved cardiac remodeling and contractile function at the chronic stage. Our findings suggest a new therapeutic option against post-infarct cardiac failure.

Characterization of a slowly degrading biodegradable polyesterurethane for tissue engineering scaffolds

The purpose of this research was to develop and characterize a novel, slowly degrading polyester-urethane. In this study, a polyester-urethane with a crystalline segment of poly((R)-3-hydroxybutyric acid)-diol linked by a diisocyanate to an amorphous segment of poly(epsilon-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. Concomitantly, 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 polyester-urethane was not cytotoxic and that the mesh was a more favorable scaffold towards cell viability. The summation of these results suggests that this polyester-urethane has the potential for tissue engineering applications.

Invited commentary

Today’s treatment of complex congenital cardiovascular defects of the right ventricular outflow tract, such as hypoplastic, stenotic right ventricular outflow tract, or the pulmonary artery in tetralogy of Fallot, are far from optimal as generally nonviable patch materials are used. This results in repeated surgical intervention for two reasons. First, the patch reconstruction and the absence of a functional pulmonary valve will lead to right ventricular failure, increased tricuspid valve regurgitation, and ventricular arrhythmias. Second, material degeneration will result in obstructive pannus overgrowth and calcification after implantation. Tissue engineering can overcome these disadvantages using a biodegradable scaffold that can be in vitro or in vivo re-cellularized to allow regeneration, remodeling, and growth potential. The present study by Fujimoto and colleagues [1Fujimoto K.L. Guan J. Oshima H. Sakai T. Wagner W.R. In vivo evaluation of a porous, elastic biodegradable patch for reconstructive cardiac procedures.Ann Thorac Surg. 2007; 83: 648-654Abstract Full Text Full Text PDF PubMed Scopus (106) Google Scholar] compared an elastomeric, biodegradable polyester urethane urea (PEUU) patch with a generally used expanded polytetrafluoroethylene (e-PTFE) patch implanted into the right ventricular outflow tract. This study, performed in the rat model, showed the superiority of the PEUU patches compared with the e-PTFE patches. The PEUU material showed high elasticity and strength and porous scaffold, allowing host fibroblast to grow into the scaffold and active synthesize collagen. In contrast there was no host cell ingrowth in the e-PTFE patch. Furthermore the PEUU scaffold was nearly completely absorbed after 12 weeks of implantation. Therefore the authors need to be congratulated for this performed study as the goal of tissue engineering has almost been completely achieved. Regeneration and remodelling potential of this biodegradable patch has been proven. Future studies will be needed, eventually in the larger animal model, to show growth potential as suggested by the authors. The impact of the biodegradable patch implanted into the right ventricular outflow tract needs to be discussed. At this early stage of right ventricular outflow tract treatment, pulmonary allografts show fast tissue degeneration and (due to the absence of viability) an outgrowth of the valve size by the patient after a short period of time. Therefore patch reconstruction of the right ventricular outflow tract is generally used to bridge the patient until a reasonable valve size can be implanted. Quality of life is limited for the patient until a valve has been implanted not to overestimate the right ventricular function. For this reason, tissue engineering should concentrate on developing a valve with regeneration, remodeling, and growth potential to overcome patch reconstruction and to allowing one-stage surgical treatment. The area of interests for biodegradable patch use would be more of those complex congenital heart diseases without the need of a valve function such as repair of complete atrioventricular communication, the Fontan procedure, enlargement of the aorta in the Norwood I procedure, or complex repair of coarctation of the thoracic aorta. In Vivo Evaluation of a Porous, Elastic, Biodegradable Patch for Reconstructive Cardiac ProceduresThe Annals of Thoracic SurgeryVol. 83Issue 2PreviewSeveral synthetic materials have been used for cardiac reconstruction in patients with complex congenital heart defects. These materials are not viable, do not grow with children, and may necessitate reoperation. We report here on the cardiac implantation of a recently developed, degradable porous material designed to facilitate cellular ingrowth during the healing process. Full-Text PDF

In Vivo Evaluation of a Porous, Elastic, Biodegradable Patch for Reconstructive Cardiac Procedures

Several synthetic materials have been used for cardiac reconstruction in patients with complex congenital heart defects. These materials are not viable, do not grow with children, and may necessitate reoperation. We report here on the cardiac implantation of a recently developed, degradable porous material designed to facilitate cellular ingrowth during the healing process. An elastomeric, biodegradable polyester urethane urea (PEUU) was processed into circular scaffolds and used to replace a surgical defect in the right ventricular outflow tract of adult rats. Control rats were implanted with expanded polytetrafluoroethylene. Histologic evaluation was performed at 4, 8, and 12 weeks postsurgery. All animals survived the surgery. Both PEUU and expanded polytetrafluoroethylene were encapsulated with fibrous tissue and had complete endothelialization on the endocardial surface with no aneurysm formation or thrombus noted. With PEUU patching, fibroblast ingrowth occurred at 4 weeks, increasing with time. In contrast, expanded polytetrafluoroethylene patches exhibited no ingrowth and elicited local inflammation that moderated with time. The PEUU patch demonstrated suitable mechanical properties and biocompatible characteristics in the right ventricular outflow tract replacement model, permitting cellular integration and endocardial endothelialization with minimal inflammation. Future application of this material as a cardiovascular scaffold seems promising.

Development of biodegradable polyesterurethane membranes with different surface morphologies for the culture of osteoblasts

Development of biodegradable polyesterurethane membranes with different surface morphologies for the culture of osteoblasts

Development of biodegradable polyesterurethane membranes with different surface morphologies for the culture of osteoblasts.

To evaluate the biocompatibility of biodegradable polyesterurethane membranes with different surface morphologies for their possible use as orthopedic biomaterials, rat osteoblasts were cultured on smooth, sunken, and particulate polyesterurethane membranes. A close interaction between cells and exposed particles on the particulate membranes was found. Cells on the particulate surfaces were well spread and flattened and had the greatest adhesion while cells on the smooth surfaces were more rounded, less spread, and less adhered. In addition, in order to investigate their in vivo degradation rates, the morphologic changes in retrieved membranes from 2, 4, and 8 weeks after subcutaneous implantation were observed by scanning electron microscopy and their average molecular weight changes were determined by gel permeation chromatography. These analyses showed that smooth membranes, compared with the two other surface membrane types, had the greatest rate and degree of molecular weight change. In contrast, the molecular weight of particulate membranes, which favor the osteoblast culture, had not changed significantly at 8 weeks postimplantation. Thus particulate polyesterurethane membrane surfaces may be of use as an orthopedic biomaterial, and polyesterurethane membranes certainly provide an ideal system for further study of the relative contributions to biocompatibility and degradation derived from surface morphology.

In vivo performance of a new biodegradable polyester urethane system used as a nerve guidance channel

Biodegradable nerve guidance channels (NGCs) represent a promising alternative to current clinical nerve repair procedures. To be suitable as a NGC material, the polymer system should possess elastomeric properties and degrade at a defined rate without interfering with the regenerating environment. Polymers made of non-crystallizable blocks of poly[glycolide-co-( ε-caprolactone)]diol and crystallizable blocks of poly[( R)-3-hydroxybutyric acid-co-( R)-3-hydroxyvaleric acid]-diol (PHB) can be modulated so as to respond to those criteria. Tubular structures were fabricated from three different types of materials containing either 41, 17 or 8 wt% PHB. Nerve regeneration through a 10 mm long NGC using a transected sciatic nerve model with an 8 mm gap was studied in rats at 4, 12 and 24 weeks. Out of 26 implanted NGCs, 23 contained regenerated tissue cables centrally located within the channel lumen and composed of numerous myelinated axons and Schwann cells. No significant difference in the degree of regeneration was observed between the various channel types. The inflammatory reaction associated with the polymer degradation had not interfered with the nerve regeneration process. Macrophages and giant cells surrounded polymer material remnants. A weight loss of 33, 74 and 88% for polymers containing 41, 17 and 8 wt% PHB was observed after 24 weeks by nuclear magnetic resonance (NMR) anaylsis, respectively. In all cases, the polymer fragments had a porous appearance with multiple surface cracks as evidenced by scanning electron microscopical analysis. Guidance channels made of 8 wt% PHB containing polymer displayed the highest degree of degradation at 24 weeks with only small polymer fragments remaining. The present study suggests that this new biodegradable elastomeric polymeric material holds promises for its utilization as nerve guidance channels.