减压气流法合成D,L-丙交酯

以质量分数85%的D,L-乳酸为原料,采用先常压除水,然后加入辛酸亚锡催化剂,减压除水,通氮气将生成的丙交酯蒸出的工艺路线,减少了原料损失,提高了产率。使用循环水真空泵代替油泵,低真空度条件下成功得到了丙交酯,降低了设备成本。然后对比了乙酸乙酯和乙醇作为溶剂对粗产品的提纯,发现无水乙醇的结晶效果好于乙酸乙酯。最后用核磁、红外等对纯化后的丙交酯进行了表征。     

Photocurable biodegradable polyesters from poly(L‐lactide) diols

α,ω‐Dihydoxy‐terminated poly(L ‐lactide)s (PLLA diols) with various molecular weights (1000, 2000 and 3000 g mol^?1) were prepared by the ring‐opening polymerization of L ‐lactide using 1,6‐hexanediol as an initiator. These were subsequently chain‐extended with the diacyl chloride of 4,4′‐(adipoyldioxy)dicinnamic acid (CAC) to obtain high‐molecular‐weight photocurable polyesters (CAC/PLLAs). The resulting polyesters were characterized by gel permeation chromatography, Fourier‐transform infrared, ultraviolet–visible and proton nuclear magnetic resonance spectroscopies, differential scanning calorimetry and thermogravimetry. These photoreactive polyesters were irradiated with a high‐pressure mercury lamp (λ > 280 nm) for 30–180 min to produce the crosslinked polyesters. The gel fraction yield increased with photocuring time, and exceeded 80 % after 180 min. The photocuring process disturbed the crystallization of the CAC/PLLA films, while it enhanced their thermal stabilities. With increasing photocuring time, both the tensile strength and modulus increased markedly. The best mechanical properties (tensile strength = 41 MPa; tensile modulus = 1550 MPa) were obtained for a CAC/PLLA‐3000 film photocured for 180 min. The tensile modulus of this photocured film was larger than that of pure PLLA. The hydrolytic degradation rates of the CAC/PLLA films in a phosphate buffer solution (pH, 7.2) of proteinaze‐k at 37 °C were much slower than those of pure PLLA films. Copyright © 2004 Society of Chemical Industry     

Microwave-assisted polymer synthesis (MAPS) as a tool in biomaterials science: How new and how powerful

Lack of reproducibility, difficult and expensive scale-up and standarization of synthetic processes are the main hurdles towards the industrial production of raw synthetic and semi-synthetic polymers for (bio)pharmaceutical applications. Time- and energy-consuming synthetic pathways that usually involve the use of volatile, flammable or toxic organic solvents are apparently cost-viable and environment-friendly for the synthesis at a laboratory scale. However, they are often not viable in industrial settings especially due to the impact they have on the product cost and the deleterious effect on the environment. This has presented hurdles to the incorporation of many new biomaterials displaying novel structural features into clinics. Nevertheless, owing to unique advantages such as shorter reaction times, higher yields, limited generation of by-products and relatively easy scale-up without detrimental effects, microwave-assisted organic synthesis has become an appealing synthetic tool. Regardless of these features, the use of microwave radiation in biomaterials science has been comparatively scarce. A growing interest in the basic aspects of the synthesis of either ceramic and polymeric biomaterials has been apparent during the last decade. This article reviews the most recent and prominent applications of MW as a versatile tool to synthesize and process organic and inorganic polymeric biomaterials, and discusses the unmet goals and the perspectives for a technology that probably has the potential to make biomaterials more accessible pharmaceutical excipients and the products that involve them more affordable to patients.     

生物降解性形状记忆聚合物及其在生物医学工程方面的应用

综述了生物降解性形状记忆聚合物如聚乳酸、聚己内酯、聚氨酯等的最新研究进展及其形状记忆机理。聚乳酸、聚己内酯和聚氨酯分别是通过相态转化、物理或化学交联以及相分离来实现形状记忆特性的。着重讨论了生物降解性形状记忆聚合物在生物医学工程领域的应用研究现状,详述了其在药物缓释、医疗器械、骨组织以及手术缝合线方面的医学应用,并展望了生物降解性形状记忆聚合物今后的发展前景。     

PLA-PCL-PLA三嵌段共聚物的合成与性能

以不同光学特性的丙交酯和己内酯为单体,辛酸亚锡为催化剂,对苯二甲醇(BDM)为引发剂,合成一系列不同PLA/PCL链段比的PLA-PCL-PLA三嵌段共聚物。采用1H-NMR、GPC、DSC对其大分子结构、分子量以及结晶熔融行为进行分析表征。同时,研究了不同PLA/PCL链段比和不同光学性质的PLA末端对嵌段共聚物力学性能的影响,结果表明:三嵌段共聚物的断裂伸长率超过1 000%,拉伸强度约为30 MPa,两端为无定型的PDLLA的嵌段共聚物的力学性能高于半结晶型的PLLA和PDLA的嵌段共聚物。     

Zwitterionic ring opening polymerization of lactide by metal free catalysts: Production of cyclic polymers

Tailor made N‐heterocyclic carbene (NHC) catalyst precursors namely (+) and (?) 1‐methyl‐3‐menthoxymethyl imidazolium chloride have been synthesized in high yield with a literature modified procedure. A reaction of catalyst precursor with potassium tert butoxide in situ generates the NHC catalyst. The zwitterionic ring opening polymerization of lactide (LA) mediated by a catalytic system composed of NHC catalyst at 25°C under argon atmosphere led to a cyclic poly(lactide) of a high molecular weight with a narrow molecular weight distribution. The cyclic poly(lactide) was characterized by NMR spectroscopy, Gel Permeation Chromatography (GPC) and Matrix‐assisted laser desorption ionization‐time of flight mass spectrometry (MALDI‐TOF MS). The NHC catalysts are active for lactide polymerization in the presence of air and elevated temperatures at 55°C. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

天然氨基酸作用下丙交酯的开环聚合反应

研究了天然氨基酸作用下丙交酯的开环聚合反应,探讨了氨基酸的酸碱性、浓度、反应条件等对聚合物相对分子质量的影响。结果表明,碱性氨基酸作用下丙交酯的开环聚合可以进行;在D, L-丙交酯的开环聚合反应中,随着氨基酸碱性的增强,聚合物的相对分子质量增大;在反应时间为48 h、反应温度为150 ℃、D,L-丙交酯/L-赖氨酸=50/1（物质的量比,下同）的条件下,可得到重均相对分子质量为12800 g/mol、相对分子质量分布为2.11的聚丙交酯;在D,D-丙交酯和L,L-丙交酯的开环聚合反应中,氨基酸的碱性越强,得到的聚合物的消旋作用越明显。     

L-丙交酯合成技术现状与进展

丙交酯作为合成聚乳酸(PLA)的中间体, 其化学及光学纯度决定着PLA的品质。本文阐述了以乳酸为原料, 两步法制备丙交酯过程中温度、压力、反应时间、催化剂种类及用量等工艺条件对最终产品收率及纯度的影响。针对高温裂解所引起的问题, 提出采用新技术、新型反应设备及开发高效均相催化剂等方法使反应在较温和的条件下进行。同时, 对溶剂重结晶法、萃取法、精馏法及熔融结晶法在丙交酯提纯上的应用及特点作了介绍, 指出综合各种精制技术的耦合法精制工艺路线将具有较好的发展前景, 而将熔融结晶技术与其他方法相耦合则是一种更为绿色可行的技术路线。最后, 指出不断研发新的绿色提纯工艺技术, 仍是丙交酯合成技术的关键所在。     

Self-Assembled Polymeric Micellar Nanoparticles as Nanocarriers for Poorly Soluble Anticancer Drug Ethaselen

A series of monomethoxy poly(ethylene glycol)-poly(lactide) (mPEG-PLA) diblock copolymers were synthesized, and mPEG-PLA micelle was fabricated and used as a nanocarrier for solubilization and delivery of a promising anticancer drug ethaselen. Ethaselen was efficiently encapsulated into the micelles by the dialysis method, and the solubility of ethaselen in water was remarkably increased up to 82 μg/mL before freeze-drying. The mean diameter of ethaselen-loaded micelles ranged from 51 to 98 nm with a narrow size distribution and depended on the length of PLA block. In vitro hemolysis study indicated that mPEG-PLA copolymers and ethaselen-loaded polymeric micelles had no hemolytic effect on the erythrocyte. The enhanced antitumor efficacy and reduced toxic effect of ethaselen-loaded polymeric micelle when compared with ethaselen-HP-β-CD inclusion were observed at the same dose in H₂₂ human liver cancer cell bearing mouse models. These suggested that mPEG-PLA polymeric micelle nanoparticles had great potential as nanocarriers for effective solubilization of poorly soluble ethaselen and further reducing side effects and toxicities of the drug.     

新型生物降解交联剂的制备及其在壳聚糖交联膜中的应用

本文用聚乙二醇和丙交酯在辛酸亚锡的催化作用下合成了可降解的二羟基中间体,再与2,4-甲苯二异氰酸酯(2,4-TDI)反应,合成了异氰酸酯基封端的一系列生物降解型交联剂.并且对中间体和交联剂进行了 FTIR分析表征.应用交联剂对壳聚糖膜材料进行交联,并对交联材料进行了吸水率,表面接触角及力学性能的测定,结果表明新型生物降解交联剂的运用不仪改善了材料吸水性,也提高了材料的力学性能.