Synthesis of Renewable Copolyacetals with Tunable Degradation

Acetal metathesis copolymerization (AMCP) of renewable isohexide diacetals and aliphatic long‐chain diacetals is reported and access to a small family of copolyacetals has been established. Crucial 1–2D NMR and MALDI‐ToF‐MS findings unambiguously confirm the existence of a copolymeric structure. In a stark contrast to the earlier reported isohexide‐polyacetals, the current copolyacetals reveal very slow degradation. Hydrolytic degradation of copolyacetal pellets is extremely slow at pH 7, whereas only 30% degradation over a period of 15 d is observed in 9 m hydrochloric acid solution. GPC investigations reveal that with increasing chain‐length the rate of degradation reduces, whereas copolyacetals with short‐chain aliphatic segments display a faster degradation profile. The reduced rate of degradation can be attributed to the hydrophobic nature of long‐chain acetal segments. In situ NMR spectroscopy reveals the existence of formates, hemiacetals, and diols as degradation products. Thus, the rate of degradation can be tuned by the judicious choice of isohexide‐diacetal and linear‐diacetals in a copolyacetal.

     

Triblock Copolymers Based on 1,3‐Trimethylene Carbonate and Lactide as Biodegradable Thermoplastic Elastomers

Summary: Biodegradable triblock copolymers based on 1,3‐trimethylene carbonate (TMC) and different lactides (i.e. D ,L ‐lactide(DLLA), L ‐lactide (LLA), D ‐lactide (DLA)) designated as poly(DLLA‐TMC‐DLLA), poly(LLA‐TMC‐LLA) and poly(DLA‐TMC‐DLA) were prepared and their mechanical and thermal properties were compared with those of high molecular weight poly(TMC) and poly(TMC‐co‐DLLA) statistical copolymers. Triblock copolymers containing crystallizable LLA or DLA segments perform as thermoplastic elastomers (TPEs) when the poly(lactide) blocks are long enough to crystallize. In blends of poly(LLA‐TMC‐LLA) and poly(DLA‐TMC‐DLA) triblock copolymers, stereo‐complex formation between the enantiomeric poly(lactide) segments occurs as demonstrated by differential scanning calorimetry and light microscopy. These blends have good tensile properties and excellent resistance to creep under static and dynamic loading conditions.

Permanent deformation (after 2 h recovery) of compression‐molded poly(TMC) and solvent‐cast poly(LLA‐TMC‐LLA) and poly(ST‐TMC‐ST) films.     

多相催化氧化法预处理丙烯腈生产过程中的废水

在常压下用催化氧化法对丙烯腈生产工艺的难降解有机废水进行处理。分别采用共沉淀法与浸渍法制备了多种金属元素组成的催化剂。实验证实:单金属元素Cu、M n和Ce对催化氧化活性均有促进作用,可使废水COD和色度的去除率达到20.0%和39.6%。多组分金属催化剂Cu M n Ce Sr对COD和色度的去除率分别达到26.5%和49.2%。经过焙烧获得的浸渍在以活性炭为载体的金属催化剂,其对废水COD及色度去除率分别达到40.9%和42.2%。由此认为所研究的催化剂可以催化降解丙烯腈废水中的有机物,并探讨了催化机理。     

可降解聚酯型聚氨酯(PE-U)的合成、表征及降解行为研究

目的本文旨在合成一种新型的可降解生物医用材料。方法以ε-己内酯、1,6-己二酸、1,6-己二醇、2,4-甲苯二异氰酸酯（TDI）为原料,采用本体熔融聚合法合成了一种可降解的聚酯型聚氨酯共聚物（PE-U）。结果采用1H-NMR、DSC、WAXD、TGA/DTG等对所得共聚物进行表征,确认了共聚物的分子结构,而其降解行为表明所得材料的降解速度可控。结论本文所合成的聚酯型聚氨酯共聚物（PE-U）,具有可控降解行为,其降解速度、吸水率等受PE-U结构的影响。     

Inhibition of plaque formation by local application of a degradable controlled release system containing cetylpyridinium chloride

Abstract The effect of a degradable controlled release system containing cetylpyridinium chloride (CPC) on plaque accumulation and gingivitis was evaluated when applied on the anterior teeth of volunteers (16–17 years) over 4 weeks. At baseline, plaque index (PI) and gingival index (GI) of the Ramfjord teeth were measured in the experimental and placebo groups, including 23 and 21 participants respectively. Following scaling and root planning, the participants were instructed to brush, using one brush stroke, the film-forming solution on the buccal surface of the maxillary and maudibular incisors, 1 × a day before bedtime. The applied active solution contained 9 mg of CPC (approximately 80 mg of 11% CPC solution), while the placebo solution was identical in formation, but without, the active agent. After 4 weeks, in the CPC-applied group, the recorded PI scores were 0.52 (±0.56) in the anterior area and 1.31 (±0.80) in the posterior area, whereas the corresponding areas in the placebo group reached 1.25 (±0.74) and 1.51 (±1.00), respectively. The P)=0 frequency in the buccal anterior surfaces after 4 weeks was 54.6% (±38.7%) in the experimental group as compared with 21.9% (±29.0%) in the placebo group (p = 0.005). In contrast to the anterior teeth, there was no significant difference between groups with respect to the PI scores in the non-applied posterior teeth. It may be postulated that the impressive 58% inhibition of plaque accumulation at the site of application is the result of an increase of the substantivity of the CPC due to its incorporation in the film–forming degradable controlled release system.     

真皮支架聚乙交酯丙交酯海绵状膜的生物相容性研究

目的:检测聚乙交酯丙交酯(polylacticacid/polyglycolicacidcopolymers,PLGA)海绵状膜的生物相容性,探讨作为细胞支架的可能性。方法:将SD大鼠20只用随机数字表法分为5组,在其背部埋置PLGA海绵状膜。不同时相点取材,做组织学观察。用PLGA浸提液进行细胞毒性试验。结果:PLGA海绵状膜在体内两三周后有大量细胞长入并伴新生血管形成,炎性细胞较少。4周开始降解,8周完全降解。细胞毒性试验表明其细胞毒性为1级。结论:此种生物材料具有较好的生物相容性和可控的降解速率,可以作为细胞支架应用于组织工程研究。     

新型可注射可降解磷酸钙骨水泥的生物相容性*☆

背景:体外实验已证实新型磷酸钙骨水泥有良好的可注射性、力学性能、抗溃散性及体外降解性能.目的:验证新型可注射、可降解磷酸钙骨水泥的生物相容性.方法:①急性毒性实验:分别向昆明小鼠尾静脉可注射新型磷酸钙骨水泥浸提液与生理盐水.②热源实验:在新西兰兔耳缘静脉注射新型磷酸钙骨水泥浸提液.③溶血实验:在兔抗凝血分别加入新型磷酸钙骨水泥浸提液、生理盐水及双蒸水.④迟发型超敏反应实验:在豚鼠肩胛骨内侧部位分别注射可注射新型磷酸钙骨水泥浸提液与生理盐水,并进行敷贴激发实验.⑤体外细胞毒性实验:在L929系小鼠成纤维细胞株培养液中分别加入可注射新型磷酸钙骨水泥浸提液、聚乙烯浸提液及苯酚溶液.⑥微核实验:分别在昆明小鼠腹腔注射可注射新型磷酸钙骨水泥浸提液、生理盐水与环磷酰胺.⑦肌肉植入实验:将新型磷酸钙骨水泥植入新西兰兔脊柱两侧肌肉内.结果与结论:新型可注射磷酸钙骨水泥无毒,无刺激性及致敏性,无热源反应,具有良好的血液相容性,植入动物肌肉后为非组织刺激物,具有良好的生物相容性,因而具有较好的生物安全性.     

肌腱损伤缝接处置入碱性成纤维细胞生长因子复合缓释降解膜的研究

目的研究碱性成纤维细胞生长因子(bFGF)复合缓释降解膜对减轻或防止肌腱粘连形成的作用. 方法用bFGF和能促进胶原纤维合成的试剂制成bFGF复合缓释降解膜.选取66只SD大鼠随机分成3组,每组22只,将左肢跟腱切断缝接.A组:切断缝接处包裹bFGF复合缓释降解膜;B组:切断缝接处只包裹单纯的降解膜;C组:切断缝接处不加任何处理.术后90天,对标本进行光镜、电镜、图像分析观察,羟脯氨酸(HYP)含量、腱周粘连定量测定,及生物力学测试. 结果 A组肌腱缝合段内的成纤维细胞和胶原纤维明显较其腱周结缔组织和B、C两组缝合段的数量多,差异有统计学意义(P＜0.05); HYP含量和最大抗拉强度均明显高于B、C两组,差异有统计学意义(P＜0.01).A组肌腱缝合段外周几乎保持原有的腱旁疏松结缔组织,与腱周分界清楚;而B、C两组肌腱缝合段外周的腱旁组织几乎均变成较致密的结缔组织,并长入腱内,与腱周分界不清.腱周粘连定量测定结果显示:A组腱周粘连程度远较B、C两组轻. 结论 bFGF复合缓释降解膜,可使损伤肌腱内部愈合快于腱周结缔组织增生,有减轻或防止粘连形成的作用.     

Transarterial chemoembolization with degradable starch microspheres, irinotecan, and mitomycin-C in patients with liver metastases

Degradable starch microspheres (DSMs) provide transient occlusion of small arteries and are thought to improve the therapeutic effect of anticancer drugs. Irinotecan (CPT-11) is one of the most effective anticancer agents. We herein report cases with liver metastases treated with transarterial chemoembolization with DSM, CPT-11, and mitomycin-C (DSM-CPT therapy). Five patients underwent DSM-CPT therapy for liver metastases that originated from colorectal cancer for four and gastric cancer for one. They all lack indication for surgery. They were all male with an age range of 42–78 years (mean, 55.2 years). Three of them had pretreatment histories with 5-fluorouracil or related agents, and four of them had combined systemic or local chemotherapy at the period. Required doses for stasis of whole blood flow of hepatic artery of DSMs were used with CPT-11 and mitomycin-C. After one to six injections, four patients had a partial response and the disease progressed in one patient with gastric cancer origin. Two of the partial response patients underwent surgery after 2 months of the partial response period. Carcinoembryonic antigen and CA19-9 levels in partial response patients decreased to 16.1% and 19.3% of the level before treatment, respectively. DSM-CPT therapy can be a potential therapy for liver metastases. Presented at the American Hepato-Pancreato-Biliary Association 2005 meeting, Hollywood, Florida, April 14–17, 2005.