高效液相色谱法测定聚乳酸中乳酸单体残留量

目的通过高效液相色谱法(high performance liquid chromatography,HPLC)测定聚乳酸材料中乳酸单体的残留量,完善此类材料的质量评价方法。方法用三氯甲烷溶解聚乳酸材料样品后,加入等体积磷酸二氢钾水溶液(20 mmol/L,pH=2.87)涡旋振荡,静置分层后取上清液,采用C18 Synergi4u Hydro-RP 80A色谱柱,进样20μL,以流速0.6 m L/min,磷酸二氢钾水溶液为流动相,柱温30℃,紫外检测波长210 nm,外标法定量并进行方法学研究,包括液相色谱系统适应性、线性范围、检出限、定量限、回收率。结果本方法中理论塔板数为10660,拖尾因子为1.32,分离度为3.81,重复性相对标准偏差为0.54%(n=5),乳酸在浓度1.05~105μg/m L范围内与峰面积保持良好的线性关系(r=0.999979),检出限为0.42μg/m L,定量限为1.05μg/m L,萃取平均回收率为94.76%(n=6),其相对标准偏差为3.04%。聚乳酸样品中乳酸单体平均残留量为144.17μg/g。结论高效液相色谱法测定聚乳酸中乳酸单体残留量具有良好的线性范围,准确度高,重复性好,萃取回收率较高且操作简单,可用于聚乳酸材料中乳酸单体残留量测定。     

Hollow Microcapsules with Enhanced Stability via Stereocomplex Assemblies

This paper presents a microfluidic approach for fabricating stereocomplexed hollow microcapsules that uses water‐in‐oil‐in‐water double‐emulsion droplets as templates. The polylactides functionalized with 2‐ureido‐4[1H]‐pyrimidinone (UPy) end groups are intermolecularly stereocomplexed by polylactides with opposite configurations to promote their self‐assembly at a water‐chloroform interface. This intermolecular interaction can significantly enhance the stability of resulting hollow microcapsules so that they preserve their shape and size after drying. Moreover, because these stimuli‐responsive polylactides can assemble and disassemble into superstructures, they can be made to release their cargo by varying the pH values. The interfacially assembled supramolecular microcapsules, which possess stimuli‐responsiveness and long‐term stability, are potentially useful for encapsulation and delivery of drugs.

     

Toughening Polylactide with Phase‐Separating Complex Copolymer Architectures

Polylactide (PLA) is a commercially produced potentially sustainable plastic that holds promise to replace petroleum‐sourced materials. Unfortunately, the brittle nature of PLA limits its current utility to disposable packaging. Melt blends of PLA and a rubbery material can rubber toughen the plastic, but often require the addition of a compatibilizer and generate opaque materials. Current efforts explore using block and graft copolymers with a majority PLA block and minority rubbery block that phase separate on the nanometer length scale to rubber toughen PLA. With these complex architectures, the polymer matrix, the minor rubbery component, and the compatibilizer are present in one molecule. Many block and graft copolymers rely on non‐sustainable rubbery blocks, which limits the sustainability of these materials. Recent work has utilized polyisoprene (PI) as the sustainable backbone for PLA graft copolymers. Post‐polymerization functionalization and copolymerization of PI provides a method to create fully sustainable PLA/PI graft copolymers that phase separate on the nanometer‐scale to make potentially tough, sustainable plastics.

     

Polydopamine – A Versatile Coating for Surface‐Initiated Ring‐Opening Polymerization of Lactide to Polylactide

An efficient way for covering various surfaces with poly(lactic acid) (PLA) is discussed. In a first step, the material is coated with polydopamine (PDA) by air oxidation of dopamine. The resulting PDA layer acts as an initiator for ring‐opening polymerization (ROP) of lactide resulting in an outer PLA shell. Since PDA sticks to almost every solid material, the methodology has a wide scope. The strategy is demonstrated with magnetic nanoparticles and non‐magnetic powders.

     

Evaluating Relative Chain Orientation of Amylose and Poly(l‐lactide) in Inclusion Complexes Formed by Vine‐Twining Polymerization Using Primer–Guest Conjugates

The relative chain orientation of amylose and poly(l ‐lactide) (PLLA) in inclusion complexes formed by phosphorylase‐catalyzed enzymatic polymerization is made clear, by using primer–guest conjugates according to a vine‐twining polymerization manner. The conjugates, which have a maltoheptaosyl moiety at COOH‐ or OH‐terminus of poly(l ‐ and d ‐lactide)s, are synthesized by copper(I)‐catalyzed click chemistry using propargyl‐terminated polylactides (PLAs) and maltoheptaosyl azide. The cavity of amylose includes PLLA, regardless of the chain orientation, when the conjugates composed of PLLA are used on the vine‐twining polymerization. On the other hand, amylose–poly(d ‐lactide) (PDLA) diblock copolymers, which are noninclusion products, are produced when the conjugates composed of PDLA are used. X‐ray diffraction (XRD) patterns of products and gel permeation chromatography (GPC) analyses of their alkaline hydrolysates strongly support that the amylose‐PLLA inclusion supramolecular polymers are produced, probably owing to the same helical direction of amylose as that of PLLA, which is responsibly induced by its chirality, regardless of the chain orientation on complexation.

     

紫外分光光度法测定胰岛素聚乳酸纳米粒中胰岛素的含量

建立一种简便易行测定胰岛素聚乳酸纳米粒中胰岛素含量的定量方法,以φ（N,N－二甲基甲酰胺：0．01mol/L酸盐）＝9：1作溶剂溶解纳米粒沉淀后,紫外分光光度法测定吸光度,从而确定其中胰岛素的含量, 检测波长276nm,线性范围1．45－14．50u/mL,平均回收率104．99％,测定结果稳定性与重现性良好,此方法操作简便,易于开展,结果可靠,应用于胰岛素聚乳酸纳米粒中胰岛素的含量测定可取得基本满意的效果。     

Polylactide Microparticles Prepared by Double Emulsion/Evaporation Technique. I. Effect of Primary Emulsion Stability

The process of microencapsulation of proteins by double emulsion/evaporation in a matrix of polylactide (PLA) can be divided into three successive steps: first, an aqueous solution of the active compound is emulsified into an organic solution of the hydrophobic coating polymer; second, this primary water-in-oil emulsion (w/o) is dispersed in water with formation of a double water-oil-water emulsion (w/o/w); third, the organic solvent is removed with formation of solid microparticles. This paper focuses on the effect of primary emulsion stability on the morphology and properties of polylactide microparticles loaded with bovine serum albumin (BSA) used as model drug. Depending on the stability of the primary emulsion, the internal structure of microparticles can be changed from a multivesicular to a matrix-like structure. Similarly, the average porosity can be controlled in a range from a few tenths of a micron to ca. 20 to 30 microns. This morphology control could find potential applications not only for the controlled drug delivery but also for the production of microporous particles intended for some specific applications, such as cell culture supports and chromatographic matrices. Although, the interplay of several processing parameters (polymer precipitation rate, polymer coprecipitation with interfacial compounds such as protein or surfactant, stirring rate, . . .) may not be disregarded, this study also indicated that a high loading of a hydrophilic drug can only be expected from a stable primary emulsion. When the stability of the primary emulsion is such as to prevent formation of macropores (>10 µm), the total pore volume is close to that of the originally dispersed aqueous drug solution.     

新型可降解聚酯材料地西泮缓释微球的研制

目的　优化制备工艺,用新型的生物可降解材料聚羟基丁酸酯—羟基戊酸酯共聚物（PHBV）与D,L-聚乳酸（PLA）共混物为基材制备以地西泮（diazepam,DZP）为模型药物的缓释微球（MS）。方法　用正交设计优化微球制备工艺,用扫描电镜（SEM）观察微球表面形态。对微球粒径及其分布、体外释药、稳定性及在动物体内药动学进行了测定。结果　微球平均粒径为(20.45±4.50) μm,粒径在15.5～35.2 μm占总数88%以上。载药量为(16.95±0.80)%,包封率为(69.68±1.13)%;体外释药方程为Q=2.7027t+13.50(γ=0.9827),动物体内实验表明,微球的血药浓度-时间曲线下面积AUC是溶液对照组的2.35倍,平均驻留时间MRT是对照组的3.62倍。微球在冰箱4℃与室温（20～25℃）条件下性质稳定。结论　微球制备工艺稳定,与DZP针剂相比,具有明显缓释作用。     

口服型聚丙交酯胰岛素微囊的初步研究

 目的：为保护胰岛素口服后不被肠道酶分解,用聚丙交酯包裹胰岛素制成。服型微囊(PLA-MCI),对其活性进行初步研究。方法：PLA-MCI体外释药胰岛素测定用福林-酚法。体内活性通过糖尿病大鼠口服后血糖变化反映。结果：体外释药实验显示PLA-MCI自30 min开始释药,6～101、已释放65%～80%,持续释药达108h。将释药后的上清液注入糖尿病兔,其 中的胰岛素仍保持降血糖的生物活性。34只非空腹糖尿病大鼠口服PLA-MCI(含胰岛素2.５mg),平均血糖下降(57士21)%,峰时为7～12h,持续作用(8土4)h,血糖下降幅度与剂量正相关。结论：PLA-MCI保持了胰岛素生物活性,具有新的药理作用模式。