Caprolactone Copolymers Research Articles

Digital Light Processing (DLP) 3D Printing of Caprolactone Copolymers with Tailored Properties through Crystallinity.

Digital light processing (DLP) 3D printing has shown great advantages such as high resolution in the fabrication of 3D objects toward a range of applications. Despite the rapid development of photocurable materials for DLP printing, tailoring properties to meet the specific demands for various applications remains challenging. Herein, we introduce copolymers of caprolactone and allyl caprolactone offering built-in functionality for thiol-ene photochemistry, thereby omitting the need for postfunctionalization. A crystalline block copolymer and an amorphous statistical copolymer were synthesized with the same comonomer composition and molecular weight. Thio-ene photocuring with a tetrafunctional thiol cross-linker was studied at different thiol to double-bond ratios for the copolymers and their blends. All formulations undergo rapid photocuring within several seconds of irradiation with slightly higher gel fractions observed for the statistical copolymer over the block copolymer under the same conditions, suggesting a somewhat higher cross-link density. Thermal properties of the networks were dependent on the presence of the semicrystalline block copolymer, where higher melting enthalpies were reached at higher block copolymer content. Similarly, crystallinity was found to be the main contributor to the mechanical properties. For a comparable composition, the modulus of a block copolymer network was found to be 31 times higher than that of the statistical copolymer network (27.7 vs 0.89 MPa). Intermediate moduli could be obtained by blending the two copolymers. DLP-printed scaffolds from these copolymers retained their thermal properties, therefore offering an efficient approach to tailoring mechanical properties, through crystallinity. Moreover, the printed scaffold displayed shape memory properties as the first example of poly(carprolactone) (PCL) copolymers in DLP printing. These materials are readily synthesized, offer fast and high-resolution 3D printing, and are degradable and cell compatible. They offer a straightforward approach to tailoring properties of PCL-based biomaterials and devices.

Nerve Capping Techniques for Neuroma Management: A Comprehensive Literature Review.

Nerve capping is a method of neuroma treatment or prevention that consists of the transplantation of a proximal nerve stump into an autograft or other material cap, after surgical removal of the neuroma or transection of the nerve. The aim was to reduce neuroma formation and symptoms by preventing neuronal adhesions and scar tissue. In this narrative literature review, we summarize the studies that have investigated the effectiveness of nerve capping for neuroma management to provide clarity and update the clinician's knowledge on the topic. A systematic electronic search following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses criteria was performed in the PubMed database combining "neuroma," "nerve," "capping," "conduit," "treatment," "management," "wrap," "tube," and "surgery" as search terms. English-language clinical studies on humans and animals that described nerve capping as a treatment/prevention technique for neuromas were then selected based on a full-text article review. The data from the included studies were compiled based on the technique and material used for nerve capping, and technique and outcomes were reviewed. We found 10 applicable human studies from our literature search. Several capping materials were described: epineurium, nerve, muscle, collagen nerve conduit, Neurocap (synthetic copolymer of lactide and caprolactone, which is biocompatible and resorbable), silicone rubber, and collagen. Overall, 146 patients were treated in the clinical studies. After surgery, many patients were completely pain-free or had considerable improvement in pain scores, whereas some patients did not have improvement or were not satisfied after the procedure. Nerve capping was used in 18 preclinical animal studies, using a variety of capping materials including autologous tissues, silicone, and synthetic nanofibers. Preclinical studies demonstrated successful reduction in rates of neuroma formation. Nerve capping has undergone major advancements since its beginnings and is now a useful option for the treatment or prevention of neuromas. As knowledge of peripheral nerve injuries and neuroma prevention grows, the criterion standard neuroprotective material for enhancement of nerve regeneration can be identified and applied to produce reliable surgical outcomes.

Can magnetisation transfer magnetic resonance imaging help for the follow-up of synthetic hernia composite meshes fate? A pilot study.

This study aims at evaluating the non-invasive Magnetic Resonance Imaging (MRI) technic to visualize a synthetic composite hernia mesh using a rodent model and to document the integration of this device over 4months. Uncoated polyethylene terephthalate mesh and synthetic composite mesh-faced on the visceral side with a chemically engineered layer of copolymer of glycolide, caprolactone, trimethylene carbonate, and lactide to minimize tissue attachment-were placed intraperitoneally in rats, facing the caecum previously scraped to promote petechial bleeding and subsequent adhesions. Meshes fate follow-up was performed 4, 10, and 16-weeks post-implantation using a rodent dedicated high field MRI. Magnetization transfer (MT) images were acquired, associated with pneumoperitonealMRI performed after intraperitoneal injection of 8mL gas to induce mechanical stress on the abdominal wall. Uncoated meshes were clearly visible using both T2-weighted and MT imaging during the whole study while composite meshes conspicuity was not so evident on T2-weighted MRI and could be improved using MT imaging. Adhesions and collagen infiltration were massive for the uncoated meshes as expected. On the contrary, composite meshes showed very limited adhesion, and, if any, occurring at the edge of the mesh, starting at the fixation points. Magnetization transfer imaging allows to detect mesh integration and, associated with pneumoperitoneum, was able to probe the effective minimizing effect of the synthetic polymeric barrier on visceral attachments. However, magnetization transfer imaging could not unambiguously allow the visualization of the mesh through the polymeric barrier.

Preparation of Nano Electrospinning Covered Stent and Its Application in the Treatment of Intracranial Aneurysm with CT Diagnosis

In the process of tissue regeneration or organ reconstruction, tissue engineering scaffolds provide strong structural support for the function of seed cells, which enables tissue engineering technology to be implemented. In the treatment of intracranial aneurysm, from the perspective of endovascular treatment, the emulsion electro-spinning method is used and the lactic acid caprolactone copolymer is taken as the matrix material to design a kind of vascular arterial stent with heparin loaded nanofibers as a film covering layer. SEM confirms that the stent has a good nanofiber structure, and TEM suggests that the core layer containing fluorescein is evenly distributed around the stent. Fourier transform infrared reflection (FTIR) shows that heparin is successfully loaded into the stent. WCA test indicates that heparin loading can improve the hydrophilicity of stent. In vitro biocompatibility/hemocompatibility test shows that the stent has good compatibility, but inhibits the proliferation of L929 and PIEC cells. With the stent as the film covering layer, the heparin loaded nanofiber stent for small vascular aneurysms successfully prepared has achieved good results in the treatment of intracranial aneurysm. CT imaging of patients treated with vascular arterial stent shows that heparin in tumor site degrades with time, which makes CT signal in mice change with time. At the same time, aneurysms gradually disappear with the implantation of covered stent. After implantation 30 d, the blood vessels of the implanted site are unobstructed and no thrombus appears.

Biodegradability of lactide–caprolactone macromonomers in wastewater

A desire to develop biorenewable materials has led to lactide–caprolactone copolymers being used in adhesive, medical, and pharmaceutical products. Use of this alternative material may diminish human impact on the environment and create products that are biocompatible. One advantage of these materials compared with other typical petroleum-based polymers is that they are easily degraded by microorganisms. In this study, the biodegradation of representative lactide–caprolactone macromonomers and an acrylic pressure sensitive adhesive incorporating these macromonomers was followed by a respirometric method using a consortium of microorganisms found in a typical wastewater treatment facility. The weight loss data of lactide–caprolactone macromonomers showed that the lowest molecular weight macromonomers with a high percentage of lactide had the greatest weight loss, which could have been caused by the greater number of ester linkages. Proton nuclear magnetic resonance data showed that for lower molecular weight copolymers, there was a preferential loss of caprolactone. Promisingly, testing of the full acrylic adhesives showed that they were easily degraded and thus provided a route to more environmentally friendly adhesive products.

Study of the processes of three-dimensional printing of caprolactone copolymers with methylphosphate groups

Reconstruction of the damaged or missed organs or skeleton fragments is an ambitious target for regenerative medicine. Tissue engineering construction (TEC) comprising three-dimensional bioresorbable scaffold and living cells can become native tissue substitute. Scaffold should correspond to strict requirements. Generally, its physical-mechanical and biochemical characteristics should be comparable with tissue to be replaced. Besides, resorption rate of scaffold material should correlate with the tissue regeneration rate in each case. Thus, the effect of scaffold manufacturing methods on its properties is an important point in TEC design and fabrication. At present study, thermo-extrusion 3D printing of bioresorbable scaffolds based on polycaprolactone and its copolymer with polyethylene glycol and methylphosphate groups, synthesized by novel chemical route, was investigated. Scaffold surface morphology and its internal structures were studied by optical and scanning electron microscopy. The effect of thermal-induced degradation on polymers properties at various 3D printing processing parameters was analysed by gel-permeation chromatography, differential scanning calorimetry and mechanical testing. It was shown that optimizing experimental parameters the developed methods of thermo-extrusion 3D printing enable effective polymer scaffolds fabrication in accordance with their 3D computer model without significant changes of physicochemical properties of initial materials.

Physical and thermal properties of l‐lactide/ϵ‐caprolactone copolymers: the role of microstructural design

AbstractUnderstanding the underlying role of microstructural design in polymers allows for the manipulation and control of properties for a wide range of specific applications. As such, this work focuses on the study of microstructure–property relationships in l‐lactide/ϵ‐caprolactone (LL/CL) copolymers. One‐step and two‐step bulk ring‐opening polymerization (ROP) procedures were employed to synthesize LL/CL copolymers of various compositions and chain microstructures. In the one‐step procedure, LL and CL were simultaneously copolymerized to yield P(LL‐stat‐CL) statistical copolymers. In the two‐step procedure, poly(l‐lactide) (PLL) and poly(ϵ‐caprolactone) (PCL) prepolymers were synthesized in the first step before CL and LL respectively were added in the second step to yield P[LL‐b‐(CL‐stat‐LL)‐b‐LL] and P[CL‐b‐(LL‐stat‐CL)‐b‐CL] block copolymers as the final products. The findings reveal that, in addition to the copolymerization procedure employed, the length and type of the prepolymer play important roles in determining the chain microstructure and thereby the overall properties of the final copolymer. Moreover, control over the degree of crystallinity and the type of crystalline domains, which is controlled during the polymer chemistry process, heavily influences the physical and mechanical properties of the final polymer. In summary, this work describes an interesting approach to the microstructural design of biodegradable copolymers of LL and CL for potential use in biomedical applications. © 2019 Society of Chemical Industry

An experimental study of drainage properties of fibrillar-structured materials for glaucoma surgery

Purpose: to study the drainage properties of fibrillar-structured materials under conditions of hydrodynamics which are maximally close to physiological conditions, using the results of a bench experiment.Material and methods. Drainage properties of fibrillary-structured materials have been studied in several bench experiments using an original device that creates conditions of eye hydrodynamics maximally close to physiological conditions. The studied materials were produced by the method of electrospinning, vacuumized and sterilized. The effect of drainage structure density and drainage type (polylactide, copolymer of polylactide and caprolactone, polycaprolactone) on the drainage capacity were evaluated, as well as the stability of their drainage properties.Results. The research revealed considerable drainage properties of all investigated objects. The study of various drainages showed a statistically significant effect of the density of the internal structure and type on the drainage capacity. Also, a nonlinear increase in the filtering capacity with a regular increase in perfusion pressure was revealed. This phenomenon, regarded as adaptive hydrodynamic properties, in addition to reducing the level of the intraocular pressure (IOP), can contribute to smoothing of diurnal fluctuations, thereby enabling the stabilization of visual functions. In the experiment, the optimal structure was determined, which corresponds to the conditions of physiological hydrodynamics of the eye and ensuring the maintenance of intraocular pressure in the low-norm region. Fibrillar structured drains made of polylactide and its copolymer with polycaprolactone with a porosity of 78–84 %, an average fiber diameter of 5–5.7 μm and a pore size of 25.8–29 μm optimally correspond to hydrodynamic conditions maximally close to physiological conditions.Conclusion. Fibrillar-structured materials have significant drainage properties depending on the density of the internal structure and the type of drainage due to threshold activation of additional pores create the conditions, close to the physiological ones, for the regulation of the IOP, and ensure the persistence of visual functions after operations.

Hybrids of Silica/Poly(caprolactone coglycidoxypropyl trimethoxysilane) as Biomaterials

Bioactive glasses stimulate bone regeneration but are brittle. Biomaterials are needed that share load with bone, promote bone regeneration, and biodegrade at controlled rates. Sol–gel hybrids can achieve this through their intimate inorganic and organic conetworks, depending on the organic polymer used. Polycaprolactone degrades slowly but lacks functional groups for the critical step of covalent coupling to the silica conetwork. Here, we synthesized a novel copolymer of caprolactone and glycidoxypropyl trimethoxysilane through one-pot ring opening polymerization (ROP). Hybrids with different organic content were fabricated using such a copolymer for the first time. The copolymer can directly bond to a silica network due its trimethoxysilane groups, which can hydrolyze, leaving silanol groups that undergo polycondensation with silanol groups of the silica network. The number of repeating units of caprolactone and glycidoxypropyl trimethoxysilane functional groups were controlled via ROP. The mechanical p...

Toward Solid-State 3D-Microbatteries Using Functionalized Polycarbonate-Based Polymer Electrolytes.

3D microbatteries (3D-MBs) impose new demands for the selection, fabrication, and compatibility of the different battery components. Herein, solid polymer electrolytes (SPEs) based on poly(trimethylene carbonate) (PTMC) have been implemented in 3D-MB systems. 3D electrodes of two different architectures, LiFePO4-coated carbon foams and Cu2O-coated Cu nanopillars, have been coated with SPEs and used in Li cells. Functionalized PTMC with hydroxyl end groups was found to enable uniform and well-covering coatings on LiFePO4-coated carbon foams, which was difficult to achieve for nonfunctionalized polymers, but the cell cycling performance was limited. By employing a SPE prepared from a copolymer of TMC and caprolactone (CL), with higher ionic conductivity, Li cells composed of Cu2O-coated Cu nanopillars were constructed and tested both at ambient temperature and 60 °C. The footprint areal capacity of the cells was ca. 0.02 mAh cm-2 for an area gain factor (AF) of 2.5, and 0.2 mAh cm-2 for a relatively dense nanopillar-array (AF = 25) at a current density of 0.008 mA cm-2 under ambient temperature (22 ± 1 °C). These results provide new routes toward the realization of all-solid-state 3D-MBs.

Co-delivery of hydrophilic and hydrophobic drugs by micelles: a new approach using drug conjugated PEG–PCLNanoparticles

Co-delivery strategy has been proposed to minimize the amount of each drug and to achieve the synergistic effect for cancer therapies. A conjugate of the antitumor drug, doxorubicin, with diblock methoxy poly (ethylene glycol)-poly caprolactone (mPEG-PCL) copolymer was synthesized by the reaction of mPEG–PCL copolymer with doxorubicin in the presence of p-nitrophenylchloroformate. The conjugated copolymer was characterized in vitro by 1H-NMR, FTIR, DSC and GPC techniques. Then, the doxorubicin conjugated mPEG–PCL(DOX–mPEG-PCL) was self-assembled into micelles in the presence of curcumin in aqueous solution. The resulting micelles were characterized further by various techniques such as dynamic light scattering (DLS) and atomic force microscopy (AFM).The encapsulation efficiency of doxorubicin and curcumin were 82.31 ± 3.32 and 78.15 ± 3.14%, respectively. The results revealed that the micelles formed by the DOX–mPEG-PCL with and without curcumin have spherical structure with average size of 116 and 134 nm respectively. The release behavior of curcumin and doxorubicin loaded to micelles were investigated in a different media. The release rate of micelles consisted of the conjugated copolymer was pH dependent as it was higher at lower pH than in neutral condition. Another feature of the conjugated micelles was a sustained release profile. The cytotoxicity of micelles were evaluated by MTT (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide, atetrazole) assay on lung cancer A549 cell lines. In vitro cytotoxicity assay showed that the mPEG–PCL copolymer did not affect the growth of A549 cells. The cytotoxic activity of the micelles against A549 cells was greater than free doxorubicin and free curcumin.

Synthesis of trimethylene carbonate/ϵ -caprolactone copolymers initiated with zinc alkoxide: influence of copolymer chain microstructure on thermal and mechanical properties

Synthesis of trimethylene carbonate/<i>ϵ</i> -caprolactone copolymers initiated with zinc alkoxide: influence of copolymer chain microstructure on thermal and mechanical properties

Dispersion polymerization of L-lactide/ε-caprolactone in supercritical carbon dioxide

The dispersion polymerization of L-lactide(LA) /e-caprolactone(CL) with stannous octoate (Sn(Oct)2) as a catalyst and n-butanol as an initiator in supercritical carbon dioxide (ScCO2) was studied. The effects of operating parameters, such as pressure, temperature, stirring rate and monomer rate of LA/CL, on the characteristics of L-lactide and e- caprolactone copolymer (PCLA) were investigated. The experimental results show that the pressure has the greatest effect on the morphology of the copolymer, and the temperature is the most decisive factor in the conversion ratio of the monomer. The changes of the conversion rate of the monomer were observed when the temperature risen from 90 to 110 °C. At the pressure of 18 MPa, the best morphology of the product can be got. Under the optimum reaction condition, PCLA with various ratio of LA/CL were obtained. Finally, fine powder particles of L-lactide and e-caprolactone copolymer (PCLA) with high molecular weight were obtained.

In vitro and in vivo evaluation of L‐lactide/ε‐caprolactone copolymer scaffold to support myoblast growth and differentiation

Skeletal muscle regeneration involves the activation of satellite cells to myoblasts, followed by their proliferation and fusion to form multinucleated myotubes and myofibers. The potential of in vitro proliferated myoblasts to treat various diseases and tissue defects can be exploited using tissue-engineering principles. With an aim to develop a biocompatible and biodegradable scaffold that supports myoblast growth and differentiation, we have developed a porous sponge with 70/30 L-lactide/ε-caprolactone copolymer (PLC) using a phase inversion combined with particulate leaching method. Degradation studies indicated that the sponge retained its structural integrity for 5 months in vitro and had undergone complete biodegradation within 9 months in vivo. The sponge supported human myoblasts attachment and its proliferation. Myoblasts seeded on the PLC sponge differentiated and fused in vitro to form myotubes expressing myosin heavy chain. Histological and molecular analyses of the PLC scaffolds seeded with green fluorescent protein-labeled human myoblasts and implanted ectopically under the skin in SCID mice demonstrated the presence of multinucleated myotubes expressing human muscle-specific markers. Our results suggest that PLC sponges loaded with myoblasts can be used for skeletal muscle engineering or for inducing muscle repair.

Histopathologic host response to polypropylene-based surgical mesh materials in a rat abdominal wall defect model

Composite polypropylene-based surgical mesh materials including various synthetic polymers and naturally occurring biomaterials have been developed to ameliorate device-associated inflammatory response and associated reduced compliance of pure polypropylene meshes. This study evaluated the histomorphologic response of three composite polypropylene-based surgical meshes, Revive™, a polycarbonate polyurethane reinforced monofilamentous polypropylene scaffold, Assure™, a polycarbonate polyurethane reinforced monofilamentous polypropylene scaffold with a resorbable anti-adhesion layer of lactide caprolactone copolymer, and Proceed™, a polypropylene mesh modified with oxidized cellulose, in a soft tissue repair model in the rat. The host inflammatory response and neotissue formation were evaluated by semiquantitative histologic scoring including the amount of cellular infiltration, angiogenesis, presence of multinucleate giant cells, fibrous connective tissue formation, and host neo-extracellular matrix deposition for up to 26 weeks. All three composite surgical mesh materials showed good integration with host tissue as indicated by rapid cellular infiltration, abundant neo-vascularization, minimal shrinkage, and the lack of visible mesh degradation. The devices elicited a similar inflammatory response and the presence of a mild foreign body response in spite of the different composition and morphology of these composite mesh materials.

Photoinduced thiol–ene crosslinking of globalide/ε‐caprolactone copolymers: Curing performance and resulting thermoset properties

AbstractThe increasing demand for bioderived polymers led us to investigate the potential use of the macrolactone globalide in thermoset synthesis via the photoinduced thiol–ene reaction. A series of six lipase‐catalyzed poly(globalide‐caprolactone) copolyesters bearing internal main‐chain unsaturations ranging from 10 to 50 and 100 mol % were successfully crosslinked in the melt with equal amounts of thiol groups from trimethylolpropane‐trimercapto propionate affording fully transparent amorphous elastomeric materials with different thermal and viscoelastic properties. Three major conclusions can be drawn from this study: (i) high thiol–ene conversions (&gt;80%) were easily attained for all cases, while maintaining the cure behavior, and irrespective of functionality at reasonable reaction rates; (ii) parallel chain‐growth homopropagation of the ene monomer is insignificant when compared with the main thiol–ene coupling route; and (iii) high ene‐density copolymers result in much lower extracted sol fractions and high Tg values as a result of a more dense and homogeneous crosslinked network. The thiol–ene system evaluated in this contribution serve as model example for the sustainable use of naturally occurring 1,2‐disubstituted alkenes in making semisynthetic polymeric materials in high conversions with a range of properties. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012.

Nanofiber-mediated controlled release of siRNA complexes for long term gene-silencing applications

Nanofiber scaffold-mediated delivery of small-interfering RNA (siRNA) holds great potential in regenerative medicine by providing biomimicking topographical signals and enhanced gene silencing effects to seeded cells. While the delivery of naked siRNA was demonstrated previously using poly (ε-caprolactone) (PCL) nanofibers, the resulting siRNA release kinetics and gene knockdown efficiencies were sub-optimal. In this study, we investigated the feasibility of encapsulating siRNA and transfection reagent (TKO) complexes within nanofibers comprising of a copolymer of caprolactone and ethyl ethylene phosphate (PCLEEP, diameter ∼ 400 nm). Sustained release of bioactive naked siRNA and siRNA/TKO complexes were obtained for at least 28 days. By copolymerizing EEP with caprolactone, siRNA release was significantly enhanced (total siRNA that was released by day 49 was ∼ 89.3–97.2% as compared to previously reported 3% by plain PCL nanofiber delivery). Using GAPDH as the model protein, bioactivity analyses by supernatant transfection revealed the partial retention of bioactivity of naked siRNA and siRNA/TKO complexes for at least 30 days. In particular, GAPDH siRNA/TKO supernatant alone induced significant gene silencing (∼40%), indicating the feasibility of co-encapsulating siRNA and transfection reagent within a single scaffold construct for sustained delivery. Direct culture of cells on siRNA incorporated scaffolds for scaffold-mediated gene transfection revealed significant gene knockdown even in the absence of transfection reagent (21.3% knockdown efficiency by scaffolds incorporating naked siRNA only). By encapsulating siRNA/TKO complexes, more significant gene knockdown was obtained (30.9% knockdown efficiency as compared to previously reported 18% by plain PCL scaffold-mediated transfection). Taken together, the results demonstrated the feasibility of co-encapsulating siRNA-transfection reagent complexes within a single nanofiber construct for sustained siRNA delivery and enhanced gene knockdown efficiency. The study also highlights the potential of PCLEEP as a platform for tailoring siRNA release kinetics for long-term gene silencing applications.

Carbon Nanotube Reinforced Polylactide−Caprolactone Copolymer: Mechanical Strengthening and Interaction with Human Osteoblasts in Vitro

This study proposes the use of carbon nanotubes (CNTs) as reinforcement to enhance the mechanical properties of a polylactide-caprolactone copolymer (PLC) matrix. Biological interaction of PLC-CNT composites with human osteoblast cells is also investigated. Addition of 2 wt % CNT shows very uniform dispersion in the copolymer matrix, whereas 5 wt % CNT shows severe agglomeration and high porosity. PLC-2 wt % CNT composite shows an improvement in the mechanical properties with an increase in the elastic modulus by 100% and tensile strength by 160%, without any adverse effect on the ductility up to 240% elongation. An in vitro biocompatibility study on the composites shows an increase in the viability of human osteoblast cells compared to the PLC matrix, which is attributed to the combined effect of CNT content and surface roughness of the composite films.

Synthesis and Characterization of Hydroxyl-Functionalized Caprolactone Copolymers and Their Effect on Adhesion, Proliferation, and Differentiation of Human Mesenchymal Stem Cells

The aim of this study was to develop new hydrophilic polyesters for tissue engineering applications. In our approach, poly(benzyloxymethyl glycolide-co-epsilon-caprolactone)s (pBHMG-CLs) were synthesized through melt copolymerization of epsilon-caprolactone (CL) and benzyl-protected hydroxymethyl glycolide (BHMG). Deprotection of the polymers yielded copolymers with pendant hydroxyl groups, poly(hydroxymethylglycolide-co-epsilon-caprolactone) (pHMG-CL). The synthesized polymers were characterized by GPC, NMR, and DSC techniques. The resulting copolymers consisting of up to 10% of HMG monomer were semicrystalline with a melting temperature above body temperature. Water contact angle measurements of polymeric films showed that increasing HMG content resulted in higher surface hydrophilicity, as evidenced from a decrease in receding contact angle from 68 degrees for PCL to 40 degrees for 10% HMG-CL. Human mesenchymal stem cells showed good adherence onto pHMG-CL films as compared to the more hydrophobic PCL surfaces. The cells survived and were able to differentiate toward osteogenic lineage on pHMG-CL surfaces. This study shows that the aforementioned hydrophilic polymers are attractive candidates for the design of scaffolds for tissue engineering applications.

Closure of the Pleural Dead Space After Pneumonectomy in a Rabbit Model: Use of Bioabsorbable Lactic Acid and Caprolactone Copolymer Cubes

The remaining pleural dead space after pulmonary resection sometimes causes serious complications, such as empyema. The objective of this study was induction of granulation tissue in uninfected pleural space after pneumonectomy in a rabbit model using implantation of bioabsorbable and porous poly-l-lactic acid and epsilon-caprolactone copolymer (PLAC) cubes. Twelve Japanese white rabbits were randomly split into two groups: the control group (n = 6) underwent simple left pneumonectomy, whereas the experimental group (n = 6) underwent left pneumonectomy followed by filling of the left hemithorax with PLAC cubes. One rabbit in each group was killed at 1, 2, 3, and 6 months after surgery, and pleural tissue was evaluated. In the experimental group, granulation tissue inside the PLAC cubes had begun to form at 1 month after implantation. From 3 months to 6 months, proliferated granulation tissue occupied the left postpneumonectomy pleural space with no residual space. The implanted PLAC material was being gradually degraded. We were able to induce self-assembled granulation tissue in the pleural space after pneumonectomy in a rabbit model using bioabsorbable PLAC cubes. The use of this technique allowed the residual pleural space to be closed after pulmonary resection.