Composition Dependence of the Thermal Behavior,Morphology and Properties of Biodegradable PBS/PTMO Segment Block Copolymer

A series of aliphatic biodegradable poly（ether-ester）s based on poly（butylene succinate）（PBS）as hard segment and poly（tetramethylene oxide）（PTMO,M_n=1 000 g/mol） as soft segment were synthesized.The composition dependence of thermal behavior,morphology and mechanical properties was investigated by differential scanning calorimetry（DSC）,atomic force microscopy（AFM）,and tensile testing.The crystallization temperature（T_c） and melting temperature（T_m） of the PBS block within poly（ether-ester）s decrease steadily at first,but decrease sharply with PTMO content above 50 wt%.Two crystallization peaks were detected for PTMO in PBSPTMO60 sample,suggesting the occurrence of fractionated crystallization.The crystallization enthalpies（△H_c） and melting enthalpies（△H_m） of PBS block decrease at first,then increase as PTMO content increases further.AFM has demonstrated that phase-separated morphology transforms from a phase of continuous hard matrix to one of continuous soft matrix containing isolated hard domain as PTMO content is increased.Finally,the results of tensile testing show that the poly（ether-ester）s present the behavior of plastics when PTMO content is below 40 wt%,and of thermoplastic elastomers with PTMO content above 50 wt%.By varying the composition of copolymer,the aliphatic poly（ether-ester）s plastics,or especially biodegradable aliphatic poly（ether-ester）s thermoplastic elastomers can be obtained.

Syntheses and Drug Delivery Property of Biodegradable Polyether-Anhydrides

Both polyanhydrides and polyethers are new types of biodegradble polymers, They are of particular interest as materials for controlled drug release system duo to their excellent surface erosion properties of polyanhydrides and excellent biocompatibility of polyethers. They hate been widly used in biomaterials. A series of polyether anhydrides elastomer were firstly synthesed through introducing PEG into the polyanhydrides chains. Their degradation and drug release property were also studied. These materials may be used in applications where materials are needed with properties more close to those of natural skin.

Preliminary Clinical Outcomes after Implantation of Newer-Generation Biodegradable Polymer-Coated Everolimus-Eluting Stent in “Real-World” Patients with Coronary Artery Disease

Background and Objective: In the contemporary practice, the use of drug-eluting stents is still associated with low mortality benefits, restenosis and stent thrombosis. To address these issues, newer generation, thin-strut, biodegradable polymer coated stents has been designed. Thus, the aim of the study is to assess the safety and clinical performance of the Everoflex (Sahajanand Medical Technologies Pvt. Ltd., Surat, India), a newer generation biodegradable polymer coated everolimus-eluting stent, in unselected “real-world” patients with coronary artery disease. Methods: It is a multicentre, retrospective, non-randomized, single-arm study enrolling all the consecutive patients who underwent implantation with the Everoflex for coronary artery disease from April 2014 to March 2016. The primary end-point of the study is 30-day major adverse cardiovascular events (MACE) rate, which consists of cardiac death, myocardial infarction, target lesion revascularization and target vessel revascularization. Stent thrombosis was also analyzed and reported. Results: A total of 340 patients were intervened successfully with 395 everolimus eluting stents (1.3 ± 0.6 stents per patient). Out of total patients (58.7 ± 10.5 years), 77.9% were male and comorbidities like diabetes and hypertension were observed in 31.2% and 35.3% patients, respectively. According to ACC/AHA classification, there were 34.4% type B lesions and 53.2% type C lesions, indicating a higher proportion of complexity involved. Moreover, 57.9% patients had multivessel disease and there were 15.4% total occlusions. At 30 days, follow-up was completed in 100% patients. The MACE was found to be 1.5%, which is a composite of 1.2% cardiac death and 0.3% target lesion revascularization. Stent thrombosis at 30 days was found to be 0.3%. Conclusion: The low incidence of MACE and stent thrombosis clearly depicts excellent safety and clinical performance of the Everoflex in unselected real world patients with coronary artery disease.

All-Comers Study of Percutaneous Coronary Interventions with Ultrathin Strut Biodegradable-Polymer Sirolimus-Eluting Stents—ORSHINE Registry

Current new generation stent technology has made remarkable progress in stent design, structure, and component material to improve its performance in reducing stent thrombosis, and restenosis compared to earlier DES and BMS. Orsiro-Sirolimus eluting stent is new generation ultra-thin strut stent with biodegradable abluminal coating that leaves a polymer free stent after drug release enhances coverage of stent struts and prevents excess neo intimal proliferation. A retrospective data analysis was done to see safety and efficacy of Orsiro in patients treated with ultra-thin DES with Orsiro stents at Sunshine Hospitals, Hyderabad. A total of 331 patients with 525 lesions were treated with 506 Orsiro stents and the major adverse cardiac events (MACE) rate and stent thrombosis (ST) at 2 years’ follow-up were analysed. MACE rate was 1.6% for an average follow-up at 2 years. Out of 2 patients who developed ST, one presented with definite acute stent thrombosis and one with possible, late stent thrombosis and 1.8% non-cardiac death reported during the follow-up. Despite many patients with complex PCI in the ACS subset, Orsiro reduced significant reduction in MACE rate in all spectrum of coronary artery disease patients with excellent acute and long-term results similar to other established FDA-approved current generations stents.

Local immunotherapy with interleukin - 2 delivered from biodegradable polymer microspheres combined with interstitial chemotherapy: a novel treatment for experimental malignant glioma.

OBJECTIVE:Local delivery of carmustine(BCNU)from biodegradablepolymers prolongs survival against experi-mental brain tumors.Moreover,paracrine administration of interleukin-2(IL-2)has been shown to elicit apotent antitumor immune response and to improve survival in animal brain tumor models.We report the use of anovel polymeric microsphere delivery vehicle to release IL-2.We demonstrate both in vitro release of cytokinefrom the microspheres and histological evidence of the inflammatory response elicited by IL-2 released from themicrospheres in the rat brain.Thees microspheres are used to deliver IL-2,and biodegradable polymer wafers

Employment of Waste from the Textile Industry for the Production of Nanocomposites Aiming at the Generation of Thermal Shrinkable Films and the Non-Formation of Microplastics

With the increase of incorrectly discarded materials in the environment, including clothes, the need for recycling and reusing them becomes one of the alternatives to work around this problem, following the law of the 3 Rs. However, these polymeric materials which are deposited in the marine environment and land generate microplastics, due to their degradation/fragmentation due to the action of the weather, in these regions, including being carried by the air and transported from various regions. With the aim of reducing the impact of this inappropriate disposal and obtaining a material that does not generate microplastics, this study used waste from the textile industry, which would be unusable, and a biodegradable polymer. The tissue residues were submitted to acid hydrolysis with sulfuric acid, in order to weaken the interactions between the cellulose fibrils and promote a better dispersion of the latter when processed with the polymer, during the extrusion process, generating biodegradable polymeric nanocomposites. The results showed that the samples submitted to acid hydrolysis presented a higher degree of crystallinity and a greater number of interactions and lower mobility of hydrogen atoms. In addition, the samples treated for a longer time showed a small release of fibrils, suggesting that this treatment can help in the production of nanocomposites during their extrusion.

RING OPENING COPOLYMERIZATION OF SUCCINIC ANHYDRIDE-ETHYLENE OXIDE BY Al(Ⅲ) ORGANOMETALLIC CATALYSTS

Ring opening copolymerization of succinic anhydride (SA) with ethylene oxide (EO)was successfully carried out by using a series of aluminum-based catalyst in 1,4-dioxane at62±2℃. The results showed that in-situ AlR_3-H_2O (R=ethyl, iso-butyl) catalysts gavehigher molecular weight (M_w～10~4), while Al(OR)_3 catalysts gave the higher alternatingcopolymer structure with slightly lower molecular weight. The in-situ AlR_3-H_2O systemshave been evaluated in more detail for the reaction which showed the optimum H_2O/Almolar ratio to be 0.5. The copolymers with different composition (F_(SA)/F_(EO)= 36/64to 45/55 mol/mol) were synthesized by using different monomer feed ratio. The melt-ing point (T_m), glass transition temperature (T_g) and enthalpy of fusion (ΔH_f) of thesecopolymers are depended on the copolymer composition and in the range of 87～102℃,-12～-18℃, and 37～66J/g, respectively. The second heating scan of DSC also in-dicated that the higher alternating copolymer was more easily recrystallized. The onsetdecomposition temperature was more than 300℃ under nitrogen and influenced by thecopolymer composition.

A Review of the Development of Properties and Structures Based on Konjac Glucomannan as Functional Materials

In recent years, konjac glucomannan（KGM） has gained considerable attention due to its non-toxic, harmless, excellent biocompatibility, biodegradability, good water imbibition as well as gel properties. KGM and its derivatives have been widely used in food science, chemical, pharmaceutical, and material areas. In this review, we will focus on the most recent advances in the structures and properties of KGM. We will first describe the influence of different modification methods on the structures and properties of KGM. Then we will review the results obtained with KGM as functional materials in different studies in the fields of hydrogels, aerogels, nanoparticles, membrane materials, microspheres and microcapsule to provide theoretical basis for the further study.

Five-year outcomes of biodegradable versus second-generation durable polymer drug-eluting stents used in complex percutaneous coronary intervention

Background:There are few data comparing clinical outcomes of complex percutaneous coronary intervention(CPCI)when using biodegradable polymer drug-eluting stents(BP-DES)or second-generation durable polymer drug-eluting stents(DP-DES).The purpose of this study was to investigate the safety and efficacy of BP-DES and compare that with DP-DES in patients with and without CPCI during a 5-year follow-up.Methods:Patients who exclusively underwent BP-DES or DP-DES implantation in 2013 at Fuwai Hospital were consecutively enrolled and stratified into two categories based on CPCI presence or absence.CPCI included at least one of the following features:unprotected left main lesion,≥2 lesions treated,≥2 stents implanted,total stent length>40 mm,moderate-to-severe calcified lesion,chronic total occlusion,or bifurcated target lesion.The primary endpoint was major adverse cardiac events(MACE)including all-cause death,recurrent myocardial infarction,and total coronary revascularization(target lesion revascularization,target vessel revascularization[TVR],and non-TVR)during the 5-year follow-up.The secondary endpoint was total coronary revascularization.Results:Among the 7712 patients included,4882(63.3%)underwent CPCI.Compared with non-CPCI patients,CPCI patients had higher 2-and 5-year incidences of MACE and total coronary revascularization.Following multivariable adjustment including stent type,CPCI was an independent predictor of MACE(adjusted hazard ratio[aHR]:1.151;95%confidence interval[CI]:1.017–1.303,P=0.026)and total coronary revascularization(aHR:1.199;95%CI:1.037–1.388,P=0.014)at 5 years.The results were consistent at the 2-year endpoints.In patients with CPCI,BP-DES use was associated with significantly higher MACE rates at 5 years(aHR:1.256;95%CI:1.078–1.462,P=0.003)and total coronary revascularization(aHR:1.257;95%CI:1.052–1.502,P=0.012)compared with that of DP-DES,but there was a similar risk at 2 years.However,BP-DES had comparable safety and efficacy profiles including MACE and total coronary revascularization compared with DP-DES in patients with non-CPCI at 2 and 5 years.Conclusions:Patients underwent CPCI remained at a higher risk of mid-to long-term adverse events regardless of the stent type.The effect of BP-DES compared with DP-DES on outcomes was similar in CPCI and non-CPCI patients at 2 years but had inconsistent effects at the 5-year clinical endpoints.

The Degradation Rate of Polyanhydride (Poly(sebacic acid), diacetoxy terminated, PSADT)

The in vitro degradation rate of polyanhydride （poly（sebacic acid）, diacetoxy terminated）, also known as PSADT, was investigated. PSADT tablets with a circular cross-section were formed using a compression molding device, and then immersed into phosphate buffer saline （PBS） for in vitro degradation experiments. The mechanisms of degradation and the degradation rate were characterized by the change in molecular weight and reduction in specimen mass. In addition, the effects of processing temperature and the geometry of the formed PSADT tablets on the rate of degradation were studied. The surface morphology at different degradation times was observed by scanning electron microscopy （SEM）. The experimental results showed that PSADT exhibited sur^hce erosion due to the fact that near zero-order degradation kinetics was observed during its degradation process. Moreover, it is found that the geometry of tablets played an important role on the rate of degradation, while the processing temperature had no significant effect on the PSADT degradation rate.

Fabrication of Porous Scaffolds Using NaHCO_3 Particulates as the Porogen Material

A new method of fabricating porous polymer scaffolds was developed, using sodium hydrogen carbonate particulates as the porogen to foam. The pore structure of polymer scaffolds can easily be manipulated by controlling the size and weight fraction of sodium hydrogen carbonate particulates. The scaffolds are highly porous with a porosity greater than 90% and with a larger pore size ranging from 100-400μm, and are well distributed with the interconnected and open pore wall structure which is necessary for tissue engineering. We investigated the effect of the porosity of scaffolds, the pore size of scaffolds and material of polymer on the mechanical properties of scaffolds. The scaffolds fabricated by the method have more big pores than those by the convenient method of salt leaching.

Zinc Oxide Nano Particles Integrated Kenaf/Unsaturated Polyester BioComposite

Increasing need for materials with special features have brought various new inventions,one of the most promising hope for new material with special features and functionalities is composites materials.Thus,this study report an integration of zinc nanoparticles into kenaf/polyester polymer composite to introduce new behavior to the composite.The composite behaviors were compared for mechanical,thermal,moisture absorption and biodegradability properties.Prepared Zinc Oxide nanoparticles entrenched in the kenaf/polyestaer composites net structure through chemical bonds between kenaf/ZnO/polyester resin,existence of ZnO significantly influence the mechanical and thermals properties of composites.Thermal analysis based on(TGA)response revealed the integration of ZnO nanoparticles improved the thermal stability when thermal decomposition temperature beyond 3650 C.The thermal cracking decreased with present of ZnO and increase with kenaf content(layers).The modulus,Tensile strength,break at elongation,flexural modulus,flexural strength and impact strength of the composites with higher content kenaf/ZnO nanoparticle are 560 MPa,58MPa,1.8%,1300 PMa,68 MPa and 31 MPa,respectively.Thus,addition of kenaf layers and ZnO results in larger mechanical properties enhancement,the results of the contact angle show improvement in wetting of the fibres with addition of ZnO nanoparticles.

SYNTHESIS OF POLY(ETHYLENE TEREPHTHALATE)-POLYCAPROLACTONE BLOCK COPOLYMER BY DIRECT COPOLYMERIZATION

Po ly(ethylene terephthalate)-polycaprolactone block copolymer (PCL-b-PET) is a polyester with improved biodegradability. In the present paper, a new direct copolymerization method of epsilon-caprolactone (epsilon-CL) and bishydroxyethylene terephthalate (BHET) in the presence of Ti(OBu)(4) was proposed for the synthesis of PCL-b-PET. The PCL-b-PET copolymer was characterized by IR, GPC and H-1-NMR techniques, and the effects of synthesis conditions, such as temperature, reaction time and concentration of catalyst on the copolymerization were discussed.

Long Coronary Lesions: Challenging Cases for Percutaneous Coronary Intervention

Long coronary lesions are associated with adverse outcomes after percutaneous coronary intervention since the era of plain balloon angioplasty. Long lesion and long stent length are considered as important predictors of restenosis after percutaneous coronary intervention. With the advent of newer generation drug eluting stents, there has been dramatic reduction in the rates of restenosis and repeat revascularization, even in complex cohort of patients with long coronary lesions. We report one such case of long coronary lesion which was intervened successfully with newer generation, thin strut, biodegradable polymer coated sirolimus-eluting stents.

Safety and Efficacy of a Novel Everolimus-Eluting Stent System in “Real-World” Patients with Coronary Artery Disease: A Report of Preliminary Outcomes

Introduction: Tetrilimus (Sahajanand Medical Technologies Pvt. Ltd., Surat, India) is a recently-introduced biodegradable-polymer coated everolimus-eluting cobalt-chromium coronary stent system with an ultra-thin strut thickness. We aimed to evaluate the clinical outcomes with Tetrilimus coronary stents in “real-world” patients with coronary artery disease. Methods: In this retrospective, single-arm, open-label, multi-center registry, all consecutive patients who received Tetrilimus stents between July-2015 and April-2016 at two tertiary-care centers in India were analyzed. Primary endpoint was 30-day incidence of major adverse cardiac events (MACE), defined as a composite of cardiac death, myocardial infarction, target lesion revascularization, and target vessel revascularization. The Academic Research Consortium (ARC)-defined stent thrombosis was assessed as additional safety endpoint. Results: During the study period, 280 Tetrilimus stents (1.4 ± 0.5 stent/patient) were implanted to treat 252 coronary lesions (1.1 ± 0.3 stent/lesion) in 208 patients (age: 57.5 ± 11.9 years). Of study population, 65.9% were males, 46.6% were hypertensives, 25% were diabetics, 36.5% were alcoholics, 29.3% were smokers, 13.9% were tobacco chewers, 5.3% had previous revascularization, and 45.2% displayed multi-vessel disease. Of treated lesions, 67.5% were complex and 18.7% had total occlusion. Average length and diameter of implanted stents were 25.5 ± 8.8 mm and 2.9 ± 0.3 mm respectively. Subsequently, 30-day MACE were reported in 2 (0.96%) patients;both cases owing to in-hospital cardiac deaths. Events of stent thrombosis or noncardiac death were not reported in any patient. Conclusion: Low MACE rates and absence of stent thrombosis at early 30-day follow-up indicates that Tetrilimus everolimus-eluting stents may have encouraging safety and efficacy in unselected “real-world” patients with coronary artery disease.

Comparison of Release Efficiencies for the Controlled-Release of Potassium Permanganate in Polycaprolactone

The application of controlled release materials in tandem with chemical oxidants has become an emerging topic within the field of environmental treatment. The controlled release kinetic and mechanistic relationship between these components is important to understand a controlled release system. Potassium permanganate (KMnO4) was used as the encapsulated material integrated into polycaprolactone (PCL) producing controlled release biodegradable polymer (CRBP) pellets. In this study, batch experiments were used to examine the release kinetics from the discharge of the pelletized encapsulated oxidant into aqueous systems at various KMnO4:PCL ratios of 1:5, 2:5, and 3:5 by mass. Experimental results indicated as the amount of KMnO4 in the PCL polymer pellets increased, a greater fraction of the oxidant was released as a function of time. The resultant data best fit a linearized diffusion model equation. Additionally, a comparison-controlled release study was conducted that contained the same oxidant at similar mass ratios. Release kinetics determined from this study could lead to effective implementation of CRBP systems and could suggest that CRBP encapsulated with KMnO4 could serve as a promising controlled release technology in a long-term and controlled manner.

Chloride-Bridged Dimeric SalphenZr(IV) Cobaltate Catalyst Unleashes the Potential of Base-Free Carbonylative Polymerization for Biodegradable PHAs

Poly(3-hydroxyalkanoates) (PHAs) are a promising class of biodegradable polymers,exhibiting properties comparable to traditional petroleum-based counterparts.Nonetheless,the widespread commercialization of PHAs is hindered by the absence of an efficient and economically viable catalytic system,impeding their competitiveness against non-biodegradable polymers.In an effort to address this challenge,we present a study on a newly developed chloro-bridged dimeric salphen zirconium cobaltate complex for the direct synthesis of PHAs via carbonylative polymerization of epoxides.The catalytic system demonstrates favorable activity under mild reaction conditions,enabling complete monomer conversion and an impressive 92% selectivity towards PHA formation.Through meticulous control experiments and mechanistic studies,we have gained crucial insights into the polymerization process.Remarkably,our findings challenge the prevailing notion of sequential ring-opening polymerization of in-situ generated β-lactones as the primary pathway.Instead,we demonstrate that the polymerization predominantly proceeds through direct co-polymerization of epoxide and carbon monoxide,unveiling a unique and efficient mechanism for PHA synthesis.

Rational design of AIE-active biodegradable polycarbonates for high-performance WLED and selective detection of nitroaromatic explosives

Luminescent polymers have garnered considerable research attention for their excellent properties and wide range of applications in multi-responsive materials,bioimaging,and photoelectric devices.Thereout,various modulations of polymer structure are often the main approach to obtaining materials with different luminescent colors and functions.However,polymers with biodegradability,tunable color,and efficient emission simultaneously remain a challenge.Herein,we report a feasible strategy to achieve degradable and highly emissive polymers by exquisite combination and interplay of aggregation-induced emission(AIE)unit and environmental-friendly epoxide/CO_(2)copolymerization.A series of polycarbonates P-TEP_(x)CN_(y)(x=0,1,2,4,30,120;y=0,1)were prepared,with emission color changed from blue to yellow by controlling the proportion of two designed AIE-active monomers.Among them,Using P-TCN as emitting layer,high performance white light-emitting diode(WLED)device with an external quantum efficiency(EQE)of 26.09%and CIE coordinates of(0.32,0.32)was achieved.In addition,the designed polymers can be used as selective sensors for nitroaromatic compounds in their nanoaggregate states.

Impact of biodegradable versus durable polymer drug-eluting stents on clinical outcomes in patients with coronary artery disease： a meta-analysis of 15 randomized trials

Background Drug eluting stents （DESs） made with biodegradable polymer have been developed in an attempt to improve clinical outcomes.However,the impact of biodegradable polymers on clinical events and stent thrombosis （ST） remains controversial.Methods We searched Medline,the Cochrane Library and other internet sources,without language or date restrictions for articles comparing clinical outcomes between biodegradable polymer DES and durable polymer DES.Safety endpoints were ST （definite,definite/probable）,mortality,and myocardial infarction （MI）.Efficacy endpoints were major adverse cardiac event （MACE） and target lesion revascularization （TLR）.Results We identified 15 randomized controlled trials （n=17 068） with a weighted mean follow-up of 20.6 months.There was no statistical difference in the incidence of definite/probable ST between durable polymer-and biodegradable polymerDES; relative risk （RR） 0.83; 95% confidence interval （CI） 0.62-1.11; P=0.22.Biodegradable polymer DES had similar rates of definite ST （RR 0.94,95% CI 0.66-1.33,P=0.72）,mortality （RR 0.94,95% C/0.82-1.09,P=0.43）,MI （RR 1.08,95% CI 0.92-1.26.P=0.35）,MACE （RR 0.99,95% CI 0.91-1.09,P=0.85）,and TLR （RR,0.94,95% CI 0.83-1.06,P=0.30） compared with durable polymer DES.Based on the stratified analysis of the included trials,the treatment effect on definite ST was different at different follow-up times：≤1 year favoring durable polymer DES and 〉1 year favoring biodegradable polymer DES.Conclusions Biodegradable polymer DES has similar safety and efficacy for treating patients with coronary artery disease compared with durable polymer DES.Further data with longer term follow-up are warranted to confirm the potential benefits of biodegradable polymer DES.

Current research on electrospinning of silk fibroin and its blends with natural and synthetic biodegradable polymers

Silk fibroin （SF） is a kind of natural polymers with a great potential in biomedical application. Due to its good biocompatibility, biodegradability and minimal inflammatory reaction, SF is an excellent candidate for generating tissue engineering scaffolds. Electrospinning is a simple and effective method to fabricate nanofibers, which has several amazing characteristics such as very large surface area to volume ratio, flexibility in surface functionalities, and superior mechanical performance. The electro- spun nanofibers from SF and its blends have been used for varied tissue engineering. This paper will give a brief review about the structure, properties and applications of SF and blend nanofibers via electrospinning.