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Since the septum plays a key role in maxillofacial growth, the effect of septorhinoplasty maneuvers and the use of poly-p-dioxanone plate during growth on maxillofacial growth was investigated in our study. Thirty-three New Zealand rabbits each with an age of 8 weeks were included in the study. Maxillofacial computed tomography was performed on all 8-weeks old rabbits. Then, the rabbits were divided into 5 groups randomly. No intervention was done on the rabbits in group 1. Nasal dorsum of the rabbits in the 2nd group were opened, and the mucosae were bilaterally elevated. In the third group underwent limited cartilage resection by preserving the nasal dorsum. Removed cartilage was crushed and placed back between the mucoperichondrial flaps for the rabbits in the 4th group. Crushed cartilage with Poly-P-Dioxanone plate was used for the rabbits in the 5th Group. Maxillofacial computed tomography was performed at the end of the 20th week and growth parameters were investigated. When the group 2 was compared with the control group, the nasal bone length was observed to be significantly shorter (P

Features of the plastic deformation of poly(p-dioxanone) fibers in air were studied. The neck propagation in the deformation speed range 0.2–15 mm/min was shown to occur in the self-excited oscillation mode. It was detected for the first time that this process is accompanied by the formation of areas with an open-pore structure. Impregnation of the fibers with brilliant green with the penetration of the die from the solution into the pores produces fibers with antimicrobial properties against the fungal culture of Candida albicans.

Currently, implantable fibrous medical devices still suffer from invisibility under current clinical imaging techniques. To address this problem, 2, 3, 5-triiodobenzoic acid (TIBA) was recruited as a contrast agent, and then a set of iodinated poly( p-dioxanone) (PPDO) fibers was fabricated via melt-spinning hybrid blends of PPDO with TIBA (PPDO/TIBA). The impact of TIBA content on the rheological behavior of blends was evaluated firstly. The physical, chemical, and thermal properties of PPDO/TIBA fibers were investigated accordingly by SEM, FTIR, DSC, and TGA. Moreover, the radiopaque property of PPDO/TIBA hybrid fibers as a potential radio-opacifying platform for medical devices was verified in vitro and in vivo. Finally, the accumulated release results of the hybrid fibers during in vitro degradation indicate the continual X-ray visibility of the hybrid fibers maintains for 22 days. This intriguing iodinated platform may pave the way for constructing fibrous materials with in-situ X-ray tracking property.

Electrospun nanofibrous mats represent a new generation of medical textiles with promising applications in heart valve tissue reconstruction. It is important for biomaterials to mimic the biological and mechanical microenvironment of native extracellular matrix (ECM). However, the major challenges are still remaining for current biomedical materials, including appropriate mechanical properties, biocompatibility, and hemocompatibility. In the present work, the novel composite nanofibrous mats of poly(p-dioxanone) (PDO) and poly(ester-urethane)ureas (PEUU) are fabricated by electrospinning system. The optimal combination ratio of PDO to PEUU may balance the mechanical properties and cellular compatibility to match the newly formed tissue. In PDO/PEUU composite nanofibrous mats, PEUU can provide the biomimetic elastomeric behavior, and PDO could endow the excellent biocompatibility. In comparison to nanofibrous mat of neat PDO, the composite showed significantly improved mechanical properties, with 5-fold higher initial elongation at break. Furthermore, human umbilical vein endothelial cells (HUVECs) were cultured on the composite to evaluate its ability to rapidly endothelialize as heart valve tissue engineering. The results revealed that PDO/PEUU composite nanofibrous mats could promote cell adhesion and proliferation, especially for the ratio of 60/40. Overall, PDO/PEUU composite nanofibrous mats (60/40) show the excellent mechanical properties, appropriate biocompatibility and hemocompatibility which meet the necessary norm for tissue engineering and may be suitable for potential heart valve tissue reconstruction.

In septorhinoplasty, septal, auricular, and costal cartilage are often used as autologous graft. Autologous grafts are preferred in nasal reconstruction. The aim of this study was to histopathologically examine the tissue compatibility and the effect on the stability and cartilage vitality of poly-p-dioxanone (PDS) plates.Ten adult New Zealand rabbits were used.Ten New Zealand rabbits were used. Septal and auricular cartilage sections were removed; one of the two cartilage grafts was left plain, and the other was sutured to a PDS plate. Grafts were placed into the back of the rabbits. After 12 weeks, the graft material was examined microscopically.The specimens did not cause any significant foreign body reaction. Within 3 months, a significant degree of color, stability, and stiffness was lost. Microscopically, inflammation, necrosis, and cartilage cell degeneration scores were statistically significantly lower in the grafts using PDS (P.05), and the vascularization, collagen, and cartilage proliferation scores were found to be statistically significantly higher (P.05). No statistically significant difference was determined in respect of the bone proliferation scores (P.05).The use of PDS plates together with cartilage provided mechanical support to the graft. Therefore, changes that disrupt the integrity of the graft, such as inflammation, necrosis, and cartilage cell degeneration, were reduced, and changes that provide greater stability, such as vascularization, collagen, and cartilage proliferation, were increased.NA Laryngoscope, 129:E129-E134, 2019.

Pierre-Alexis Mouthuy,1,2 Maja Somogyi Škoc,3 Ana Čipak Gašparović,1 Lidija Milković,1 Andrew J Carr,2 Neven Žarković1 1Laboratory for Oxidative Stress, Rudjer Boskovic Institute, Zagreb, Croatia; 2Botnar Research Centre, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, Medical Science Division, University of Oxford, Oxford, UK; 3Department of Materials, Fibres and Textile Testing, University of Zagreb, Zagreb, Croatia Abstract: Electrospun filaments represent a new generation of medical textiles with promising applications in soft tissue repair. A potential strategy to improve their design is to combine them with bioactive molecules. Curcumin, a natural compound found in turmeric, is particularly attractive for its antioxidant, anti-inflammatory, and antimicrobial properties. However, investigating the range of relevant doses of curcumin in materials designed for tissue regeneration has remained limited. In this paper, a wide range of curcumin concentrations was explored and the potential of the resulting materials for soft tissue repair applications was assessed. Polydioxanone (PDO) filaments were prepared with various amounts of curcumin: 0%, 0.001%, 0.01%, 0.1%, 1%, and 10% (weight to weight ratio). The results from the present study showed that, at low doses (≤0.1%), the addition of curcumin has no influence on the spinning process or on the physicochemical properties of the filaments, whereas higher doses lead to smaller fiber diameters and improved mechanical properties. Moreover, filaments with 0.001% and 0.01% curcumin stimulate the metabolic activity and proliferation of normal human dermal fibroblasts (NHDFs) compared with the no-filament control. However, this stimulation is not significant when compared to the control filaments (0%). Highly dosed filaments induce either the inhibition of proliferation (with 1%) or cell apoptosis (with 10%) as a result of the concentrations of curcumin found in the medium (9 and 32 µM, respectively), which are near or above the known toxicity threshold of curcumin (~10 µM). Moreover, filaments with 10% curcumin increase the catalase activity and glutathione content in NHDFs, indicating an increased production of reactive oxygen species resulting from the large concentration of curcumin. Overall, this study suggested that PDO electrospun filaments loaded with low amounts of curcumin are more promising compared with higher concentrations for stimulating tissue repair. This study also highlighted the need to explore lower concentrations when using polymers as PDO, such as those with polycaprolactone and other degradable polyesters. Keywords: electrospinning, electrospun filaments, polydioxanone, PDO, curcumin, human fibroblasts

Novel pseudo-polyrotaxanes (PPRs) consisting of poly(p-dioxanone) (PPDO) and cyclodextrins (CDs) were obtained via heat-cool (H-C) cycles. The optimum preparation condition for achieving the highest yield was investigated, which was selected as follow: 3 times H-C cycles in 72 h of PPDO and CDs dissolved in DMF at 60 °C. The PPRs were further characterized by using wide-angle X-ray diffraction (WAXD), NMR, FT-IR, and thermogravimetric analysis (TGA). It was found that PPDO could be wrapped by CDs units. Compare to the single PPDO chain, the PPRs have better thermal stability. Moreover, the hydrophilicity of PPRs is also enhanced significantly determined by the water static contact angle tests. In addition, hydrolytic degradation experiments showed that the PPRs had unique degradation behaviors. The construction of the PPRs based on the PPDO and CDs would further expand the application of PPDO as biomaterials.

Einleitung: Die partielle Meniskektomie zur Behandlung von Meniskusdefekten ist eine der häufigsten Prozeduren in den USA. Die Meniskektomie führt zu biomechanischen Veränderungen im Kniegelenk, die mit einem erhöhten Risiko für Gonarthrose einhergehen. Actifit®-Implantate sind biologisch abbaubare Polyurethan-Menisken und substituieren die biomechanischen Eigenschaften des Meniskus. Diese Monographie befasst sich mit den intraoperativen Versagenskräften von Actifit®-Implantaten in Bezug auf das Nahtmaterial, der Temperatur oder der Art des Nährmediums. Methodik: Es werden 128 Actifit®-Implantate in jeweils 15 mm große Abschnitte geteilt, mit Poly-p-dioxanon (PDS II) Fäden oder Polybraid-Fäden horizontal durchstochen und nach 15-minütiger Einlegedauer unter 5 N uniaxialem Zug im Nährmedium Purisole oder Ringer-Lactat bei 20°C oder 37°C auf die Versagenskraft getestet. Die Testung erfolgt mit dem eigens dafür errichteten Testgerät Electroforce® Testbench (Bose, MN, USA) im biomechanischen Labor des Julius-Wolff-Instituts (JWI), Berlin in Kooperation mit dem Centrum für Muskuloskeletale Chirurgie (CMSC) der Charité Universitätsmedizin Berlin. Ergebnisse: Das Ringer-Nährmedium zeigt eine signifikant höhere Versagenskraft als die Purisole Testreihe (55.3 ± 5.6 vs. 51.2 ± 6.7 N; P < .0002). Es gibt keine signifikanten Differenzen innerhalb der Versagenskräfte des Nahtmaterials (54.0 ± 6.1 Polybraid vs 52.6 ± 6.8 PDS II). Der Vergleich der Temperatur zeigt eine signifikant höhere Versagenskraft in der 37°C Gruppe (54.3 ± 6.3 N vs. 52.3 ± 6.5 N; P = .041). Schlussfolgerung: Die Ringer-Lösung führt zu einer höheren Versagenskraft als die Purisole-Lösung. Grundlage dieses Phänomens könnte der pH-Wert von 6,5 der Ringer-Lösung im Vergleich zu 5,2 bei der Purisole-Lösung darstellen. Hierbei stellt das Polycaprolacton, welches zu 80 % im Polyurethanmeniskus aufzufinden ist, den Hauptort der Degradation dar und kann mithilfe eines niedrigeren pH-Werts beschleunigt hydrolysiert werden. Diese Esterhydrolyse führt zu einer pH-Wertsenkung und somit kann aus dieser heterogenen sauren Katalyse eine homogene Katalyse mithilfe von Implantat-Bestandteilen und folglich ein autokatalytischer Prozess resultieren. Dieser Degradationsprozess kann in vivo eine Inflammation und eine Schmerzsymptomatik verursachen., Introduction: A partial meniscectomy as a treatment for meniscus defects is among one of the most common procedures in the USA. Nevertheless, removing the menisci changes the biomechanical properties of the knee, which can lead to an increased risk of gonarthrosis. Actifit® implants are biodegradable polyurethane menisci and have the function of artificially simulating the biomechanical properties of the meniscus. This monograph addresses the intraoperative failure loads of the sutures of Actifit® implants in regard to the suture material and type or temperature of the irrigation fluid. Methods: 128 Actifit® implants were prepared with horizontal sutures and uniaxial load to failure tests using the Electroforce® Testbench (Bose, MN, USA) machine were performed. The testing conditions varied between a sorbitol-mannitol irrigation solution (Purisole) or Ringer’s solution, non-absorbable braided polyester sutures (NABP) or poly-p-dioxanone (PDS II) sutures or a temperature of 20°C or 37°C to simulate an intraoperative setting. All tests were conducted in the Julius-Wolff-Institute (JWI) in Berlin in cooperation with the musculoskeletal department of the Charité University Hospital in Berlin. Results: The Ringer solution showed a significant increase in the tearing force of the sutures in comparison to the sorbitol-mannitol solution (Purisole) (55.3 ± 5.6 vs. 51.2 ± 6.7 N; P < .0002). There were no significant findings among the different suture materials (54.0 ± 6.1 Polybraid vs 52.6 ± 6.8 PDS II). The temperature of 20°C led to a decreased tearing force in comparison to the 37°C group (54.3 ± 6.3 N vs. 52.3 ± 6.5 N; P = .041). Conclusions: The most notable finding of this study is the discrepancy in tearing forces in regard to the used solution. The usage of the sorbitol-mannitol solution (Purisole) led to a decreased mean tearing force and thus indicated a change in the structure of the Actifit® implants. While investigating this phenomenon, the changes in pH were the predominant difference between the two solutions. This led to the conclusion that lowering the pH might change the structure of the Actifit® implants and therefore the speed of degradation. Furthermore, this process of degradation is described as ester-hydrolysis-dependent and consequently, a lower pH is a part of it. The pH changes can lead to an autocatalytic process as well as to inflammation and pain in the postoperative knee.

In this study, biodegradable poly(p-dioxanone) (PPDO)/octamethyl-polyhedral oligomeric silsesquioxanes (ome-POSS) nanocomposites were fabricated by the simple solution casting method with various ome-POSS loadings. Scanning electron microscopic observations indicate that ome-POSS is well dispersed in the PPDO matrix. Effect of ome-POSS on the isothermal melt crystallization and dynamic mechanical properties of PPDO in the nanocomposites were studied in detail. It shows that the overall crystallization rates are faster in the nanocomposites than in neat PPDO and increase with the increase in ome-POSS loadings; however, X-ray diffraction patterns, POM and the Avrami exponent suggest that the crystal structure and the crystallization mechanism do not change despite the presence of ome-POSS. The mechanical property of PPDO/ome-POSS nanocomposites was enhanced with respect to neat PPDO.

Spinal cord injury (SCI) is often associated with scarring and cavity formation and therefore bridging strategies are essential to provide a physical substrate for axonal regeneration. In this study we investigated the effects of a biodegradable conduit made from trimethylene carbonate and ε-caprolactone (TC) containing poly-p-dioxanone microfilaments (PDO) with longitudinal grooves on regeneration after SCI in adult rats. In vitro studies demonstrated that different cell types including astrocytes, meningeal fibroblasts, Schwann cells and adult sensory dorsal root ganglia neurons can grow on the TC and PDO material. For in vivo experiments, the TC/PDO conduit was implanted into a small 2-3 mm long cavity in the C3-C4 cervical segments immediately after injury (acute SCI) or at 2-5 months after initial surgery (chronic SCI). At 8 weeks after implantation into acute SCI, numerous 5HT-positive descending raphaespinal axons and sensory CGRP-positive axons regenerated across the conduit and were often associated with PDO microfilaments and migrated host cells. Implantation into chronically injured SCI induced regeneration mainly of the sensory CGRP-positive axons. Although the conduit had no effect on the density of OX42-positive microglial cells when compared with SCI control, the activity of GFAP-positive astrocytes was reduced. The results suggest that a TC/PDO conduit can support axonal regeneration after acute and chronic SCI even without addition of exogenous glial or stem cells.Biosynthetic conduits can support regeneration after spinal cord injury but often require addition of cell therapy and neurotrophic factors. This study demonstrates that biodegradable conduits made from trimethylene carbonate and ε-caprolactone with poly-p-dioxanone microfilaments alone can promote migration of different host cells and stimulate axonal regeneration after implantation into acute and chronic spinal cord injury. These results can be used to develop biosynthetic conduits for future clinical applications.

In order to expand the application of poly(p-dioxanone) or PPDO in biomedical area, a series of novel copolymers were synthesized successfully by one-step, melted copolymerization of p-dioxanone (PDO) and l -phenylalanine N-carboxyanhydride ( l -Phe-NCA) monomers. With the in-feed molar ratio of l -Phe-NCA/PDO equal to 1/20, the conversions of the two kinds of monomers were calculated from 1H NMR. The average molecular weight and polydispersity of the copolymer increase with the increasing reaction time and catalyst concentration. However, the conversions of the two kinds of monomers did not change with the reaction conditions. A three-step mechanism is presented and proved by high resolution 1H NMR and IR spectrums.

The variations of structure and property of poly( p -dioxanone) (PPDO) in the process of photo-oxidative degradation and the mechanism of degradation were investigated in this work. The photo-oxidative degradation of PPDO was performed in air under ultraviolet light with two kinds of wavelength 365.0 nm and 253.7 nm. The extent of photo-oxidative degradation of the polymer was determined by morphological analysis, weight loss ratio, changes of viscosity and scanning electron microscope method (SEM). Infrared spectrometry (IR) and nuclear magnetic resonance (NMR) method were used to infer the mechanism of the photo-oxidative degradation. The changes of glass-transition temperature ( T g ) and melting temperature ( T m ) were characterized by differential scanning calorimetric (DSC) test. The morphological examination, IR and NMR testing revealed that the extent and mechanism of photo-oxidative degradation for PPDO are not closely correlated with its initial molecular weight. The main influence of initial molecular weight on the degradation is to change the ultimate distribution of the molecular weight. The conclusion is supported by the results of DSC test. All results from the research show the excellent photodegradable property of PPDO.

A new biodegradable copolymer of cellulose diacetate and poly(p-dioxanone) (PPDO) was prepared through a couple-grafting procedure. PPDO was functionalized with the isocyanate group, and then PPDO terminated with the isocyanate group was enabled to react with the hydroxyl groups of cellulose diacetate. The length of PPDO graft chains can be controlled easily by using the prepolymers of PPDO with different molecular weights. The resulting products were thoroughly characterized with FT-IR,1H-NMR. The mechanical properties of the copolymers were affected greatly by the length of PPDO segment.

A bioabsorbable poly-p-dioxanone (PPDO) stent with a novel sliding-lock structure was fabricated to treat stenotic peripheral vessels. The sliding-lock PPDO stents have greater radial strength (107 kPa) than PPDO stents with conventional net-tube structure (32 kPa). The sliding-lock PPDO stents were implanted into the iliac arteries of pigs, and implantation success rate was 90% indicating the feasibility of this design. Additionally, we found that sliding-lock PPDO stents kept vessels patent, although by 3 and 6 months post implantation, luminal diameter decreased slightly due to intimal hyperplasia. At 1 month post implantation, the stents were sparsely covered with endothelial cells, and by 6 months, the stents were mostly absorbed and inflammatory reaction gradually decreased as the stents were absorbed. This study shows favorable mechanical strength, degradability and efficacy for the sliding-lock PPDO stents, and supports further research and development of this unique design of polymer stents for applications in vascular devices.

Nonisothermal and isothermal cold crystallization behaviors of poly(p-dioxanone) (PPDO) were investigated by differential scanning calorimetry (DSC). There were two crystallization exotherms—a majo...

Buscando estratégias que repercutam na melhoria da interação entre materiais poliméricos biorreabsorvíveis e o crescimento celular, o presente estudo in vitro teve como objetivo estudar a influência de blendas de PPD/PHB na adesão celular e crescimento de fibrocondrócitos obtidos a partir de cultura primária. As blendas de PPD/PHB foram preparadas pelo método de evaporação de solvente nas composições 100/0, 60/40 e 50/50 e caracterizadas por microscopia eletrônica de varredura (MEV). Observações ultra-estruturais mostraram alterações na morfologia celular, sugerindo que os fibrocondrócitos podem responder a alterações no substrato alterando seu perfil fenotípico. As análises com MTT demonstraram que as blendas não apresentaram citotoxicidade e permitiram a adesão e proliferação dos fibrocondrócitos sobre os substratos em todas as suas composições. O ensaio colorimétrico com Sirius Red evidenciou a capacidade de manutenção da síntese de matriz extracelular colágena sobre as amostras, concluindo-se que as blendas de PPD/PHB podem ser indicadas para o cultivo celular. In order of seek strategies to improve the interaction between bioreabsorbable polymer materials and cellular growth, this work aimed at evaluating in vitro the influence of PPD/PHB blends on cell adhesion and fibrochondrocytes growth. Fibrochondrocytes cells were obtained by primary extraction from enzymatic digestion methods. The PPD/PHB blends were prepared by casting with 100/0, 60/40 and 50/50 compositions, and were characterized by scanning electron microscopy (SEM). After 6, 48, 120 and 168 hours in culture, ultrastructural observations showed changes in cell morphology, suggesting that the fibrochondrocytes can respond to substrate modifications, changing their phenotypic profile. The MTT analyses showed that the blends did not present cytotoxicity and allowed fibrochondrocytes adhesion and proliferation on the membranes in all compositions. The colorimetric Sirius Red test revealed the capability of extracellular matrix synthesis on the blends, from which one can conclude that the PPD/PHB blends are not cytotoxic and can be indicated for cell culture.

A series of poly(p‐dioxanone‐urethane) (PPDO‐PU) copolymers were produced by chain extending reaction of poly(p‐dioxanone) (PPDO) diol with 1,6‐hexamethylene diisocyanate (HDI) and toluene‐2,4‐diisocyanate (TDI). The chain structure of the copolymers can be easily controlled by varying the molecular weight of PPDO diol and the structure of diisocyanate. Several instruments such as DSC, POM, TG, and Capillary Rheometer have been employed to investigate the structure–properties relationship of PPDO‐PU copolymers. The results show that varying the structure and the content of chain extenders will influence the crystallization behavior, thermal stability, mechanical performance, and rheological behavior of the products significantly. The insertion of urethane groups into PPDO polymer chains enhances the mechanical performance of the copolymers.

Novel composites based on poly(p-dioxanone) (PPDO) and organically modified cationic and anionic clays have been prepared using the technique of melt-extrusion. The intercalation of the organic modifier in the clays and the dispersion degree of the organically modified clays in the PPDO composites have been analyzed by wide-angle X-ray scattering (WAXS) and Atomic Force Microscopy (AFM). Ah inmiscible system was obtained for PPDO/cationic clays, whereas in the case of PPDO/anionic clays exfoliated nanocomposites were succesfully obtained.

In this study, we find out the possibilities to make conduit for nerve regeneration using biodegradable polymers, which have enough mechanical strength in surgery. Cell adhesion (PC12) behaviors about various nerve conduits have not great difference compared to control. This is regarded due to specific structure of nerve conduits formed nano-fibers. In the case of PPD, we observed better phenotype of adhered cell than PLGA samples. Also, PPD-PLGA bi-layered nerve conduits were more effective than PLGA nerve conduit for in vitro evaluation.

The crystallization behaviors of poly(p-dioxanone) (PPDO) with different molecular weights (MWs) have been studied using a differential scanning calorimetry. The results showed that the MW of PPDO affects the crystallization rate and crystallinity obviously during the dynamic crystallization process. The Avrami equation has been used to analyze the overall isothermal crystallization of PPDO. Avrami exponents ranging from 2 to 3 were obtained with good fits (correlation coefficients were greater than 0.999 in all the cases) at Tc ranged from 55 to 75°C. Although no significant influence of MW on Avrami exponent has been found, the MW of PPDO plays dominant role on the rate constant k. The values of k increase with the MW in a Tc range from 55 to 75°C. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2331–2335, 2006

Prepolymers of both poly(p-dioxanone) (PPDO) and poly(butylene succinate) (PBS) reacted in the presence of toluene-2,4-di-iso-cyanate(TDI) as a chain extender to produce higher-molecular-weight chain-extended products (PPDOBS) in suitable reaction conditions. The novel biodegradable polymers were characterized by NMR, DSC, TG and WAXD. The results of thermal oxidative degradation show that chain-extended products have better thermal stability than PPDO. The thermal degradation of PPDOBS shows two stages, the first due to the degradation of PPDO segment of PPDOBS, and the second to the degradation of PBS segment. DSC measurement shows that the PPDOBS has only one Tg, which means that PPDO has good compatibility with PBS. PPDOBS has two crystalline peaks during the cooling scan, but no crystalline peak during the heating scan. The diffraction peaks of PPDOBS appear at the same 2θ angles as that of homopolymers, suggesting that the PPDO and PBS of the chain-extended products preserve their own crystal form. This kind of novel biodegradable polymer is expected to have potential applications in environmentally friendly materials.

Solution-grown lamellar crystals of poly(p-dioxanone) (PPDX) have been crystallized isothermally from butane-1,4-diol at 100°C. The crystal structure of PPDX has been determined by interpretation of X-ray fiber diagrams of PPDX fibers and electron diffraction diagrams of lozenge-shaped chain-folder lamellar crystals. The unit cell of PPDX is orthorbombic with space group P2 1 2 1 2 1 and parameters: a=0.970 nm, b=0.74 mm, and c (chain axis) = 0.682 nm. There are two chains per unit cell, which exist in an anti parallel arrangement.

This paper reviews the synthesis, properties, and applications of biodegradable polymer, poly(p-dioxanone) (PPDO), and its copolymers. Recent progress in ring-opening polymerization of p-dioxanone employing several effective catalysts is described. Properties of PPDO are given. The copolymers based on PPDO are also discussed.

The melt behaviour of poly(p-dioxanone) (PPD) has been studied by differential scanning calorimetry (DSC). Crystallinity and morphology were evaluated by modulated differential scanning calorimetry (MDSC) and polarizing optical microscopy. The melting curves showed two melting endotherms, a higher melting (HM) peak at a constant temperature of 105 degreesC and a lower melting (LM) peak at temperatures depending on the crystallization temperature T-c. The corresponding peak temperature increased linearly with T-c, yielding an extrapolated value for the equilibrium melting temperature, T(m)degrees, of 114 degreesC. The occurrence of HM peak is a result of recrystallization. The optical micrographs showed a spherulitic morphology, with regular concentric rings, which might be caused by a periodical twisting of the lamellae during crystallization. (C) 2001 Elsevier Science Ltd. All rights reserved.

An investigation was carried out on the crystallization behavior of p-dioxanone polymers using differential scanning calorimetry (DSC). Kinetic analyses were performed on data collected primarily during isothermal crystallization. Isothermal data were treated within the framework of the classical Avrami equation. Using this approach, both the Avrami exponent, n, and the crystallization half-time, t1/2, were evaluated and their implications are discussed for each system studied. It is shown that a small change in the polymer's composition greatly affects the crystallization kinetics, as well as the crystallizability of the materials. Additionally, nonisothermal crystallization under controlled heating and cooling rates was explored. In the case of cooling from the melt, the Ozawa theory and the recently proposed Calculus method were employed to describe the nonisothermal crystallization kinetics. In view of our results, the validity of these two estimation techniques for determining important kinetic and morphological parameters is also discussed. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 742–759, 2001

Bioabsorbable implants have found an increasing number of uses, including fractures of the malleoli, radial head, and distal radius, among others. We have begun to use bioabsorbable pins for the purpose of hammertoe correction. K-wires have been the traditional method of fixation for arthroplasty/arthrodesis in the correction of hammertoes. We describe an alternative method using poly-p-dioxanone 2-mm absorbable pins. This method may prove to reduce infection by avoiding exposed pins and gives patients an earlier return to normal footwear.

Two different fibrous clays, halloysite nanotubes (HNTs) and organically modified attapulgite (OAT), were chosen to prepare poly(p-dioxanone) (PPDO)/clay nanocomposites by in-situ polymerization. The influence of surface character and geometric structure of the clays on the properties of the nanocomposites were investigated systematically concerning with their crystallization behaviors, thermal stabilities, rheological behaviors, and mechanical performances. The effect of clay content on the properties of the nanocomposites was also discussed, taking PPDO/HNTs nanocomposites for example. The results showed that HNTs was more effective in improving the crystallization rate, thermal stability as well as mechanical performance. In addition, the crystallization rate and rigidity of nanocomposites increased with increasing HNTs loading. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

PPDO was successfully electrospun into continuous, ultrafine fibers by using DMSO as solvent for the first time. The concentration of PPDO in DMSO and the electrospinning temperature were optimized. PPDO/LAP nanocomposites were also electrospun in DMSO. At 70 degrees C, ultrafine PPDO fibers were obtained from 35 wt% solution and the PPDO/LAP nanocomposite fibers were yielded from 55 wt% solution. Electrospun fibers of the PPDO/LAP nanocomposites showed higher degree of crystallinity due to the presence of embedded nanoparticles.

The degradation behavior and the effect on angiogenesis of multiblock copolymers based on poly(p-dioxanone)- and poly(epsilon-caprolactone)-segments (PDC) were studied in vivo. PDC is a multifunctional biomaterial combining degradability and shape-memory capabilities. The "in vivo" degradation of PDC is characterized by a fragmentation occurring at the material tissue interface. This observation is consistent with the enzyme supported degradation behaviour, which was determined "in vitro". PDC revealed to induce the formation of blood micro-vessels nearby in the periimplantary tissues. Both might explain the good PDC integration into tissues in terms of a strong connection between the implant and the periimplantary tissue. Micro blood-vessels might be involved in the clearance of the small particles, which appear in the periimplantary tissue when PDC degrades.

Poly(p-dioxanone) (PPDO) and poly(ethylene succinate) (PES) prepolymers were reacted together using toluene-2,4-diisocyanate (TDI) as a chain extender to produce high molecular weight of chain-extended products of PPDO and PES (PPDOES) in a suitable reaction condition. The novel biodegradable polymers were characterized by 1H-NMR, DSC, POM and WAXD. DSC measurement shows that PPDOES has only one Tg, which means that PPDO has good compatibility with PES. Beside this, the glass transition temperatures and the melting temperatures of PPDOES increased with the increase of PES content. The crystallization rate of PPDOES was slower than that of PPDO as confirmed by DSC and POM. The diffraction peaks of PPDOES appear at the same 2θ angles as that of homopolymers, suggesting that PPDO and PES segment of the chainextended products reserve their own crystallization form. The results of thermal oxidative degradation show that chain-extended products have better thermal stability than PPDO.

A new biodegradable copolymer of chitosan and poly(p-dioxanone) (PPDO) was prepared through a protection-graft-deprotection procedure using N-phthaloyl-chitosan as an intermediate. PPDO terminated with the isocyanate group was allowed to react with hydroxyl groups of the N-phthaloyl-protected chitosan, and then the phthaloyl group was cleaved to give the free amino groups. The length of PPDO graft chains can be controlled easily by using the prepolymers of PPDO with different molecular weights. The resulting products were thoroughly characterized with FT-IR, (1)H NMR, TG, DSC, SEM, and WAXD. The copolymers were used as drug carriers for sinomenine (7,8-didehydro-4-hydroxy-3,7-dimethoxy-17-methyl-9alpha,13alpha,14alpha-morphinan-6-one) and these exhibited a significant controlled drug-releasing behavior whether in artificial gastric juice or in neutral phosphate buffer solution.