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This study proposes composite stents with core–shell structure. Biodegradable polyvinyl alcohol (PVA) yarns are twisted and then coated with polycaprolactone/polyethylene glycol (PEG) blends. The coated yarns are weft knitted into braids and then thermally treated to form composite stents with core–shell structure. The morphological, mechanical, and biological characteristics of the formed composite stents are evaluated to determine the effects of PEG concentration. Results show that composite stents acquire the flexibility of PVA yarns and elasticity of weft knits. The presence of PEG positively influences composite stent performance. When the PEG concentration is 30 wt%, composite stents exhibit a compressive strength of 6.15 N and cell viability of 97.32% after a 24 h of culture. The selected materials are biodegradable, and the novel structure meets the requirements of bioresorbable vascular stent, which suggests that the proposed composite stents have good potential for advancement. 相似文献
3.
Qichen Peng Ruimin Guo Yangyang Zhou Ruidi Teng Yulin Cao Shiqing Mu 《Macromolecular bioscience》2023,23(4):2200402
Endothelialization of the aneurysmal neck is essential for aneurysm healing after endovascular treatment. Mesenchymal stem cell (MSC)-seeded stents can promote aneurysm repair. The biological effects of coated and uncoated nitinol intracranial stents seeded with MSCs on vascular cells and macrophage proliferation and inflammation are investigated. Two stent coatings that exert pro-aggregation effects on MSCs via different mechanisms are examined: gelatin/polylysine (G/PLL), which enhances cell adhesion, and silk fibroin/SDF-1α (SF/SDF-1α), which enhances chemotaxis. The aim is to explore the feasibility of MSC-seeded coated stents in the treatment of intracranial aneurysms. The G/PLL coating provides the highest cytocompatibility and blood compatibility substrate for MSCs and vascular cells and promotes cell adhesion and proliferation. Moreover, it enhances MSC secretion and regulation of vascular cell and macrophage proliferation and chemotaxis. Although the SF/SDF-1α coating promotes MSC secretion and vascular cell chemotaxis, it induces a greater degree of macrophage proliferation, chemotaxis, and secretion of pro-inflammatory factors. MSC-seeded stents coated with G/PLL may benefit stent surface endothelialization and reduce the inflammatory response after endovascular treatment of intracranial aneurysm. These effects may improve aneurysm healing and increase the cure rate. 相似文献
4.
《Macromolecular bioscience》2018,18(7)
Biodegradable stents are not established in neurovascular interventions. In this study, mechanical, radiological, and histological characteristics of a stent prototype developed for neurovascular use are presented. The elasticity and brittleness of PLA 96/4, PLDL 70/30, PCL, and PLGA 85/15 and 10/90 polymers in in vitro experiments are first analyzed. After excluding the inapt polymers, degradability and mechanical characteristics of 78 PLGA 85/15 and PLGA 10/90 stent prototypes are analyzed. After excluding PLGA 10/90 stents because of rapid loss of mass PLGA 85/15 stents in porcine in vivo experiments are analyzed. Angiographic occlusion rates 7 d, 1 month, 3 months, and 6 months after stent implantation are assessed. Histological outcome measures are the presence of signs of inflammation, endothelialization, and the homogeneity of degradation after six months. One case of stent occlusion occurs within the first 7 d. There is a prominent foreign‐body reaction with considerable mononuclear and minor granulocytic inflammation combined with incomplete fragmental degradation of the struts. It is possible to produce a stent prototype with dimensions that fit the typical size of carotid arteries. Major improvements concerning thrombogenicity, degradation, and inflammatory response are required to produce biodegradable stents that are suitable for neurovascular interventions. 相似文献
5.
Joseph Jagur‐Grodzinski 《先进技术聚合物》2006,17(6):395-418
Recently investigated applications of polymeric materials for tissue engineering, regenerative medicine, implants, stents, and medical devices are described in the present review. Papers published during the last 2 years about polymeric materials used for preparation of various polymeric scaffolds, methods of fabrication of such scaffolds and their effectiveness in providing support for cell growth and development into various tissues and enhancing or mimicking an extracellular network (ECM's) have been cited. Papers describing the use of such polymeric materials for tissue engineering of cartilage and bones were cited. The exciting developments in the field of regenerative medicine, based on application of the self‐assembled biocompatible polymeric scaffolds for regeneration of tissues and organs are described in some detail. The use of the biocompatible and biodegradable collapsible polymeric stents, as well as the use of biocompatible, but not necessarily biodegradable polymeric materials for protective coatings of metallic stents and reservoirs of drugs, preventing restenosis and other post‐operative complications that may occur after insertion of a stent, have been reviewed. Clinical results pointing out the advantages of such treatments, as well as results indicating their limitations, have been cited. New formulas, for coating implants, stents, and other medical devices, have been discussed. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
6.
Jiahui Dong Yahua Li Xiaofeng Wang Yajing Liu Kewei Ren Xuedi Liu Han Zhang Zongming Li Xinwei Han Hiroshi Uyama Qian Li 《Macromolecular bioscience》2023,23(10):2300113
Central airway stenosis is a condition that the diameter of the trachea or main bronchus shrinkage is caused by external compression or internal tissue hyperplasia, which can cause difficulty breathing, asphyxia, and even death. Airway stenting is an easy way to restore the patency of the central airway, but airway stents commonly used in clinical practice can lead to complications such as mucus plugging, bacterial infection, and granulation tissue hyperplasia. Moreover, the non-degradable characteristic makes it requires a second operation to remove, which has the potential to cause tissue damage. In this study, a biodegradable airway stent is fabricated by microinjection molding using the bioelastomer of poly (L-lactide-co-ε-caprolactone) as the matrix material. The airway stent has excellent mechanical properties and an appropriate degradation rate. The hydrophilic surface of the airway stent can inhibit mucus plugging. The loading of silver nanoparticles and cisplatin endows the stent with antibacterial and anti-hyperplastic functions. In vitro and in vivo experiments demonstrate that this study provides an antibacterial and anti-hyperplastic biodegradable airway stent with elastic properties to avoid secondary removal operation and reduce complications associated with mucus plugging, bacterial infection, and granulation tissue hyperplasia. 相似文献
7.
Chang-Jiang Pan Jia-Ju Tang Ya-Jun Weng Jin Wang Nan Huang 《Colloids and surfaces. B, Biointerfaces》2009,73(2):199-206
In the present study, the different drug-eluting controlled biodegradable polymer coatings were fabricated on stainless steel stents. The coatings were not only uniform and smooth but also had excellent mechanical property. The drug release profiles of drug-eluting stents were studied in detail in this study. Depending on the drug type, different drug-eluting stents exhibited different drug release profile. There were two basic release profiles for different drug-eluting stents, i.e., two-phase release profile with burst release or linear release profile without burst release. Incorporating heparin in the rapamycin or curcumin eluting stents can improve the average drug release rate of both and the burst release of rapamycin. The average drug release rate increased with the increase of drug loading but was not proportional to increase of the ratio of drug/polymer. Fabricating the control release layer on rapamycin-eluting stent surface can prevent the burst release of rapamycin and prolong the release period of rapamycin. All results showed that the drug release profile of drug-eluting stents depends on many parameters including drug type, ratio of drug/polymer, and drug carrier properties. 相似文献
8.
Liquid chromatography‐tandem mass spectrometry (LC‐MS/MS) method has proved to powerful research tool due to its sensitivity, high selectivity, and high throughput efficiency..Sirolimus was extracted from plasma by two‐step extraction procedure using chloroform as extracting solvent. Signal intensity was high using ESI+ source provided for the quantitation of samples. Chromatographic separation was performed on phenomenax C‐18 column (250 × 4.60 mm 5microns).Mobile phase contains acetonitrile, water (80; 20 v/v) + 0.1% acetic acid, flow rate 1 mL/min.The retention time of Sirolimus 8.4 min, the total run time10 min. Linearity correlation coefficients (r2) curve was 0.997183.calibraction range 10–1000 ng/mL. The UV detection of Sirolimus was at 278(277.78) nm. Sirolimus coated drug eluting stents, MRM (Multiple reaction monitoring) transition of Sirolimus m/z 936.83–208.84 was selected to obtain maximum sensitivity. LC/MS/MS results exhibited consistency in drug content on the stent surface. In‐vitro release kinetic indicated the release of Sirolimus in 41 days from the date of implanted. Drug release was found at the first day, burst release was observed at 7th day of implantation. This study involved pharmacological coating of stents, based on the notion that sustained systemic local delivery of anti‐proliferative agents. LC‐MS/MS method has been successfully used in the pharmacokinetic analysis of Sirolimus coated drug eluting stents. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
9.
The objective of this study was to evaluate degradation behavior and the feasibility of biodegradable polymeric stents in common bile duct (CBD) repair and reconstruction. Various molar ratios of lactide (LA) and glycolide (GA) in poly(l-lactide-co-glycolide) (PLGA) were synthesized and processed into a circular tubing of ∼10.0 mm outer diameter and a wall thickness of about 2.0 mm. This tubing was cut into 40.0 mm length to form CBD stents. The stents were placed into human bile to determine the degradation behavior in vitro. The morphology, configuration, mass loss, water uptake, molecular weight and composition changes were examined. The PLGA with LA/GA = 71/29 exhibited an acceptable degradation life and was chosen as an in vivo stent material. These PLGA stents were used in common bile duct exploration (CBDE) and primary suturing for rats. Degradation status of the stents was examined and comparison was made between those before and after surgical procedure. The results showed that the polymer stents exhibited the same biomedical functions as T tubes and spontaneously disappeared from CBD in 4-5 weeks. Therefore, the PLGA stents fits the requirements in repair and reconstruction of CBD, to support the duct, guide bile drainage and reduce T-tube-related complications. 相似文献
10.
Zsuzsanna Vértes 《Journal of Thermal Analysis and Calorimetry》2005,82(1):225-228
Summary The age dependence of thermal denaturation was monitored in rats anaesthetized after they're born at 7th, 14th, 21st, 28th, 35thand 42nddays. The samples were stored in rigor or physiological saline solution. The DSC scans in the early age groups show a low
temperature exotherm (connective tissues: from gel to liquid crystal transition) and one endotherm (it is very probably the
myosin). During further development the endotherms became more and more complex (due to the development of contractile system).
At 42 days the scans seem to be similar to the adult ones. In the two buffers the endotherms markedly differ showing that
the ATPase activity is present. In adult uterus, treated with nucleotides or estrogen, this activity significantly differs
from the skeletal muscle. On the basis of our results we suppose, that the age dependent changes are decisive processes in
the development of rat uterus. 相似文献
11.
Jiun‐Tang Huang Li Hannah‐Qiuhua Renata Szyszka Vladimir Veselov Gail Reed Xiande Wang Sylvester Price Lori Alquier Gyorgy Vas 《Journal of mass spectrometry : JMS》2012,47(2):155-162
A molecular imaging application was developed to characterize the drug distribution on CYPHER® and NEVO? Drug‐eluting Stents using MALDI Qq‐ToF analytical methodology. The coating matrix, laser energy, laser frequency, spatial resolution (related to rastering speed) and mass spectrometer parameters were optimized to analyze drug distribution in both durable and biodegradable polymer matrices. The developed method was extended to generate data from stents explanted from porcine coronary arteries. Due to the method's intrinsic specificity, it offers a significant advantage over other techniques in that it allows low‐level detection of the target molecule without biological interferences from the blood or tissue. The method is also capable of detecting drug‐related degradation products both from the finished stent product and from explanted stents. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
12.
Elena Badea Lucreţia Miu P. Budrugeac Maria Giurginca A. Mašić Nicoleta Badea G. Della Gatta 《Journal of Thermal Analysis and Calorimetry》2008,91(1):17-27
A comprehensive investigation has been made of a set of 14th to 16th-century parchment bookbindings from the Historical Archives of the City of Turin. Advanced physico-chemical techniques, such as thermal analysis (DSC, TG and DTA), spectroscopy (FTIR and UV-Vis-NIR), scanning electron microscopy (SEM) and unilateral nuclear magnetic resonance (NMR-ProFiler) were employed to assess specific deterioration processes occurring at different levels in the hierarchical structure of parchment. Changes in the measured physical and chemical parameter values of parchment due to interaction with the environment were used to identify possible deterioration pathways. 相似文献
13.
冠脉介入支架治疗技术发展至今已有30余年,从裸金属支架发展到药物洗脱支架乃至今天新兴的生物可吸收支架,不断的推动着冠心病介入治疗向前进步。生物可吸收支架的理念是治疗后无异物留体内。总的来讲,支架开通并保持狭窄或堵塞血管畅通的使命在血管修复后即完成,此后最理想的状态便是支架也随之消失。生物可吸收高分子支架(Bioresorbable Polymeric Scaffold,BRPS)由于使用的材料不仅可以人为地设计和改性,而且是药物的良好载体,因此成为该领域研究的热点。本文从材料、结构设计、加工工艺等方面介绍了BRPS的研究进展,重点讨论了激光切割和3D打印制备BRPS的两种方法,以及BRPS的降解性能及要求,最后对BRPS面临的挑战及发展方向做了展望。 相似文献
14.
To better investigate the degradation and biocompatibility of waterborne biodegradable polyurethanes for tissue engineering, a series of new waterborne biodegradable polyurethanes (PEGPUs) with low degree of crosslinking was synthesized using IPDI, BDO and L-lysine as hard segments, PCL and PEG as soft segment. The bulk structures and properties of the prepared polyurethanes were characterized by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), tensile mechanical tests and water contact angle (WCA) measurements. The degree of microphase separation was slightly improved because of the lowered crosslinking degree of these PEGPUs in comparison with the high cross-linking degree samples, leading to good mechanical properties, as indicated by DSC and stress-strain data. Moreover, biodegradability of the polyurethanes was evaluated in phosphate buffer solutions (PBS) under different pH values and enzymatic solution at pH 7.4 through weight loss monitoring. The results suggested that the degradation of these PEGPUs was closely related to their bulk and surface properties. And the degradation products didn’t show apparent inhibition effect against fibroblasts in vitro. These studies demonstrated that the waterborne biodegradable polyurethanes could find potential use in soft tissue engineering and tissue regeneration. 相似文献
15.
Bakhshi R Darbyshire A Evans JE You Z Lu J Seifalian AM 《Colloids and surfaces. B, Biointerfaces》2011,86(1):93-105
Stent angioplasty is a successful treatment for arterial occlusion, particularly in coronary artery disease. The clinical communities were enthusiastic about the use of drug-eluting stents; however, these stents have a tendency to be a contributory factor towards late stage thrombosis, leading to mortality in a significant number of patients per year. This work presents an innovative approach in self-expanding coronary stents preparation. We developed a new nanocomposite polymer based on polyhedral oligomeric silsesquioxanes (POSS) and poly(carbonate-urea)urethane (PCU), which is an antithrombogenic and a non-biodegradable polymer with in situ endothelialization properties. The aim of this work is to coat a NiTi stent alloy with POSS-PCU. In prolonged applications in the human body, the corrosion of the NiTi alloy can result in the release of deleterious ions which leads to unwanted biological reactions. Coating the nitinol (NiTi) surface with POSS-PCU can enhance surface resistance and improve biocompatibility. Electrohydrodynamic spraying was used as the polymer deposition process and thus a few experiments were carried out to compare this process with casting. Prior to deposition the NiTi has been surface modified. The peel strength of the deposit was studied before and after degradation of the coating. It is shown that the surface modification enhances the peel strength by 300%. It is also indicated how the adhesion strength of the POSS-PCU coating changes post-exposure to physiological solutions comprised of hydrolytic, oxidative, peroxidative and biological media. This part of the study shows that the modified NiTi presents far greater resistance to decay in peel strength compared to the non-modified NiTi. 相似文献
16.
Encasement of metallic cardiovascular stents with endothelial cell‐selective copolyetheresterurethane microfibers
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Cardiovascular metallic stents established in clinical application are typically coated by a thin polymeric layer on the stent struts to improve hemocompatibility, whereby often a drug is added to the coating to inhibit neointimal hyperplasia. Besides such thin film coatings recently nano/microfiber coated stents are investigated, whereby the fibrous coating was applied circumferential on stents. Here, we explored whether a thin fibrous encasement of metallic stents with preferentially longitudinal aligned fibers and different local fiber densities can be achieved by electrospinning. An elastic degradable copolyetheresterurethane, which is reported to selectively enhance the adhesion of endothelial cells, while simultaneously rejecting smooth muscle cells, was utilized for stent coating. The fibrous stent encasements were microscopically assessed regarding their single fiber diameters, fiber covered area and fiber alignment at three characteristic stent regions before and after stent expansion. Stent coatings with thicknesses in the range from 30 to 50 µm were achieved via electrospinning with 1,1,1,3,3,3‐hexafluoro‐2‐propanol (HFP)‐based polymer solution, while a mixture of HFP and formic acid as solvent resulted in encasements with a thickness below 5 µm comprising submicron sized single fibers. All polymeric encasements were mechanically stable during expansion, whereby the fibers deposited on the struts remained their position. The observed changes in fiber density and diameter indicated diverse local deformation mechanisms of the microfibers at the different regions between the struts. Based on these results it can be anticipated that the presented fibrous encasement of stents might be a promising alternative to stents with polymeric strut coatings releasing anti‐proliferative drugs. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
17.
Cs. Novák A. Végh S. Marokházi G. Pokol L. Szente 《Journal of Thermal Analysis and Calorimetry》1994,41(1):181-190
Racemic free mandelic acid and its methyl, ethyl, isoamyl and benzyl esters were found to form inclusion complexes with all
the three studied natural cyclodextrins proved by thermoanalytical results. Differences between the solid state stability
of guests were detected mainly by evolved gas analysis. Even signs of an eventual optical resolution by molecular inclusion
were observed in several cases, but still not sufficiently proven. Due to the rather high volatility and low melting points
of the majority of guest substances DSC technique was found to be suitable for studying the cyclodextrin complexes of mandelic
acid.
Dedicated to Prof. József Szejtli on the occasion of his 60th birthday 相似文献
18.
《Journal of membrane science》2005,246(2):193-201
Solid conducting biodegradable composite membranes have shown to enhance nerve regeneration. However, few efforts have been directed toward porous conducting biodegradable composite membranes for the same purpose. In this study, we have fabricated some porous conducting poly(dl-lactide) composite membranes which can be used for the biodegradable nerve conduits. The porous poly(dl-lactide) membranes were first prepared through a phase separation method, and then they were incorporated with polypyrrole to produce porous conducting composite membranes by polymerizing pyrrole monomer in gas phase using FeCl3 as oxidant. The preparation conditions were optimized to obtain membranes with controlled pore size and porosity. The direct current conductivity of composite membrane was investigated using standard four-point technique. The effects of polymerization time and the concentration of oxidant on the conductivity of the composite membrane were examined. Under optimized polymerization conditions, some composite membranes showed a conductivity close to 10−3 S cm−1 with a lower polypyrrole loading between 2 and 3 wt.%. A consecutive degradation in Ringer's solution at 37 °C indicated that the conductivity of composite membrane did not exhibit significant changes until 9 weeks although a noticeable weight loss of the composite membrane could be seen since the end of the second week. 相似文献
19.
Jie Gong Xiao‐Jie Lou Wen‐Da Li Xin‐Ke Jing Hong‐Bing Chen Jian‐Bing Zeng Xiu‐Li Wang Yu‐Zhong Wang 《Journal of polymer science. Part A, Polymer chemistry》2010,48(13):2828-2837
A novel multiblock aromatic–aliphatic copolyester poly(ethylene‐co‐1,6‐hexene terephthalate)‐copoly(1,4‐dioxan‐2‐one) (PEHT‐PPDO) was successfully synthesized via the chain‐extension reaction of dihydroxyl teminated poly(ethylene‐co‐hexane terephthalate) (PEHT‐OH) with dihydroxyl teminated poly(1,4‐dioxan‐2‐one) (PPDO‐OH) prepolymers, using toluene‐2,4‐diisocyanate as a chain extender. To produce PEHT‐OH prepolymer with an appropriate melting point which can match the reaction temperature of PEHT‐OH prepolymer with PPDO‐OH prepolymer, 1,6‐hexanediol was used to disturb the regularity of poly(ethylene terephthalate) segments. The chemical structures and molecular weights of PEHT‐PPDO copolymers were characterized by 1H NMR, FTIR, and GPC. The DSC data showed that PPDO‐OH segments were miscible well with PEHT‐OH segments in amorphous state and that the crystallization of copolyester was predominantly contributed by PPDO segments. The TGA results indicated that the thermal stability of PEHT‐PPDO was improved comparing with PPDO homopolymer. The novel aromatic–aliphatic copolyesters have good mechanical properties and could find applications in the field of biodegradable polymer materials. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2828–2837, 2010 相似文献
20.
Y. Chen L. Tan W. Zhou J. Su Y. Yang Y. Hu 《Journal of Thermal Analysis and Calorimetry》2009,96(1):307-313
To obtain a biodegradable polymer material with satisfactory thermal properties, higher elongation and modulus of elasticity,
a new copolyester, poly(hexylene terephthalate-co-lactide) (PHTL), was synthesized via direct polycondensation from terephthaloyl
dichloride, 1,6-hexanediol and oligo(lactic acid). The resulting copolyesters were characterized by proton nuclear magnetic
resonance (1H NMR), differential scanning calorimetry (DSC), thermogravimetry (TG) and wide-angle X-ray scattering (WAXS). By using the
relative integral areas of the dyad peaks in 1H NMR spectrum of copolyesters PHTL, the sequence lengths of the hexylene terephthalate and lactide units in the resultant
copolyesters are 3.5 and 1.5, respectively. Compared to poly(hexylene terephthalate) (PHT), PHTL has lower T
m but higher T
g due to the incorporation of lactide unit into the main chains of copolyesters. The degradation test of copolyesters under
a physiological condition shows that the degradability of PHTL is sped up due to incorporation of lactide segments. 相似文献