两亲性杂臂星型嵌段共聚物胶束的制备、表征及载药性能研究

以溴代异丁酰溴与3,5-二羟基苯甲酸制备3,5-二(2-溴-2丙酰氧基)苯甲酸,再与聚乙二醇单甲醚酯化,合成含溴大分子引发剂PEG-Br2。以苯乙烯为单体,利用原子转移自由基聚合方法(ATRP)合成了两种不同亲疏水段比例的两亲性星型杂臂嵌段共聚物PEG-b-(PS)2。本实验利用FTIR、1H-NMR、GPC等技术对聚合物的分子结构及分子量进行表征,利用透析法制备聚合物胶束;采用AFM对聚合物胶束的纳米结构进行观察;采用荧光探针法测得其临界胶束浓度(CMC)分别为0.99 mg·L-1和0.59 mg·L-1;利用DLS测得聚合物胶束粒径为150 nm左右;以疏水型抗肿瘤药物氨甲喋呤(MTX)为模型药物,对载药胶束的体外释药行为进行了研究,测得聚合物胶束的载药量分别为为13.32%和10.00%,包封率分别为61.75%和46.82%。结果表明,随着疏水段的增大,星型杂臂嵌段共聚物胶束药物包载量及CMC随之降低,且在人体pH条件下药物释放较低;同时发现两种载药胶束在肿瘤细胞酸性条件下释药速率增加。综上,此类结构的聚合物胶束作为抗肿瘤药物MTX的载体分子具有很好的应用前景。     

pH和还原双重敏感性超支化纳米胶束的制备及其释药性能

将聚乙二醇二缩水甘油醚(PEGDGE)与胱胺(Cys)置于水溶液中,通过亲核开环反应制备出超支化聚合物,并自组装形成多核-壳结构的纳米胶束,再通过甲氨蝶呤(MTX)与纳米胶束间的疏水作用制备出载药胶束。用FT-IR、~1H-NMR、DLS、SEM等方法对聚合物结构和胶束粒径与形貌进行表征,采用噻唑蓝(MTT)法测试纳米胶束和载药胶束的细胞毒性。结果表明:聚合物经过透析纯化后自组装形成纳米胶束,其粒径约为100nm,呈均一球形;载药胶束对MTX的载药率为10.32%;当载药胶束处于模拟肿瘤环境中时,酸性和还原性条件可刺激药物释放。细胞毒性实验表明,纳米胶束具有优良的生物相容性;载药胶束具有较强的抗肿瘤活性。     

嗜神经病毒衍生肽RVG29介导的靶向纳米载药胶束的合成及抗肿瘤活性

将羧基化的水溶性葡聚糖(Dex)与紫杉醇(PTX)化学偶联, 制得载药纳米胶束M(PTX), 再将M(PTX)与嗜神经性病毒衍生肽(RVG29)化学偶联, 得到RVG29靶向的载药纳米胶束M(RVG,PTX). 采用核磁共振氢谱(¹H NMR)测定了Dex-PTX及RVG-Dex-PTX键合物的分子量, 并对2种胶束进行了表征, 考察了2种胶束对肿瘤细胞的抑制效果及细胞凋亡情况, 观察了C₆细胞对荧光标记M(RVG,PTX)和M(PTX)的摄取情况. 结果表明, 羧基化葡聚糖-紫杉醇键合物的分子量约为16500, 紫杉醇的质量约为葡聚糖的20%, RVG29的质量约为葡聚糖的10%. 2种胶束的粒径在45~60 nm之间; M(RVG,PTX)胶束对C₆细胞的抑制作用具有浓度和时间依赖性, 细胞抑制率随着作用时间和药物浓度增加而增加, 且M(RVG,PTX)胶束对C₆细胞的抑制作用强于M(PTX)胶束. 细胞摄取实验结果表明, 与M(PTX)相比, C₆细胞摄取了更多的M(RVG,PTX)胶束. 如果先用游离的RVG29处理C₆细胞, 再进行细胞实验, 则M(RVG,PTX)胶束对C₆细胞生长的抑制作用及被C₆细胞摄取的比率显著降低, 与 M(PTX)相当. 表明靶向载药胶束M(RVG,PTX)中的RVG29保留了游离RVG29的活性, 对C₆细胞依然具有靶向效应, 从而介导了M(RVG,PTX)被C₆细胞的摄取, 增强了对C₆细胞的生长抑制作用. 由于M(RVG,PTX)胶束只使用水溶性葡聚糖作载体, 不涉及疏水高分子链段, 不需要分别制备载药高分子和靶向高分子然后再共组装, 因而制备过程比较简单, 同时具有载药和靶向功能.     

叶酸修饰星型端氨基PEG-PLGA纳米胶束的制备及肿瘤细胞靶向作用

合成了星型多臂端氨基聚乙二醇(PEG)/聚乳酸-羟基乙酸(PLGA)两亲性嵌段共聚物(4s-PLGA-PEG-NH₂), 并通过核磁共振和凝胶渗滤色谱法对其结构进行表征; 采用溶剂挥发法制备阿霉素载药纳米胶束, 利用EDC缩合法与叶酸偶联, 得到叶酸修饰的星型端氨基PEG-PLGA纳米胶束; 采用动态光散射、 紫外光谱及透射电镜等手段对纳米胶束进行了表征; 对载药纳米胶束在HeLa细胞中的摄取及细胞毒性进行了初步评价. 结果表明, 经叶酸修饰的星型多臂端氨基PEG-PLGA载药纳米胶束可有效提高HeLa细胞的摄取率以及对HeLa细胞的杀伤率, 表明其可作为一类新型的靶向抗肿瘤药物递送载体.     

新型壳聚糖基自组装纳米胶束紫杉醇药物释放载体

以N-胆甾醇琥珀酰基-O-羧甲基壳聚糖(CCMC, 胆甾醇基取代度6.9%)为原料, 在水溶液中通过探头超声处理制备其自组装凝胶纳米胶束, 采用稳态荧光探针法考察临界胶束浓度, 并通过透射电镜和动态激光散射仪检测胶束的形态大小. 以紫杉醇为模型药物, 采用透析法制备载药CCMC纳米胶束, 并通过高效液相色谱法(HPLC)考察其在纳米胶束中的包载及释放情况. 结果显示, CCMC为两亲性高分子, 在水溶液中能形成粒径为198.4 nm的规则球状胶束, 临界胶束浓度为0.018 mg/mL. 紫杉醇顺利包载于CCMC-纳米胶束内, 载药量高达34.9%; 随着载药量的增加, 胶束粒径呈增大的趋势. 体外释放实验结果显示, CCMC纳米胶束能延缓紫杉醇的释放, 释药速度和释放介质pH值密切相关.     

基于炔烃参与的多组分聚合构建氧化还原双重响应型高分子药物载体

为了拓展多组分聚合方法在药物载体领域应用,基于铜催化的炔烃多组分聚合设计合成含有二硒键的氧化还原响应型两亲性聚合物,与阿霉素(DOX)在水溶液中通过自组装方式构建纳米载药胶束.通过实验技术手段对纳米载药胶束表征可知,纳米载药胶束的粒径在130 nm左右,临界胶束浓度(CMC)值为0.23 mg/mL,在人体正常生理条件下结构稳定.肿瘤中含有浓度较高的活性氧(ROS)或谷胱甘肽(GSH),聚合物主链中二硒键在氧化还原条件下断裂,导致聚合物降解,DOX从纳米载药胶束中逐渐释放,且累积释放量可达100%,并发现该类载药胶束在GSH环境中药物释放性能优于ROS环境.该工作通过多组分聚合方式可以便捷构建氧化还原双重响应型的两亲性聚合物,在肿瘤微环境中表现出特异的降解性能,为开发设计智能响应型高分子药物载体提供新的思路.     

纳米孔硅灰石载药抗菌止血材料的研究

采用溶胶-凝胶法,以聚氧乙烯-聚氧丙烯-聚氧乙烯三嵌段共聚物(P₁₂₃)为模板剂,合成了纳米孔硅灰石(np-WT),用np-WT载盐酸万古霉素研制了一种新型的载药抗菌止血材料,并对其止血性能进行了研究。结果表明：np-WT具有排列有序的纳米孔道结构,其孔径在2 nm左右,高比表面积的np-WT能够明显地缩短体外部分凝血活酶时间(APTT)和凝血酶原时间(PT)。载药np-WT能够在磷酸缓冲溶液(PBS)中缓慢地释放药物,载药np-WT对其凝血性能没有明显的影响。载药np-WT对大肠杆菌有很好的抗菌作用,细胞毒性实验表明：载药np-WT无细胞毒性。载药np-WT具有很好的止血性能,能够阻止兔背部伤口的流血和缩短其流血时间。     

叶酸修饰硬脂酸接枝白芨共聚物的合成及作为抗肿瘤药物载体的研究

制备了叶酸修饰硬脂酸接枝白芨(FA-BSPs-SA)的共聚物,通过氢核磁光谱(1H NMR)、紫外-可见分光光度法(UV)及红外光谱法(IR)对其进行结构表征.以乳化-溶剂挥发法制备了载多西他赛胶束并对其进行表征,并采用噻唑蓝(MTT)法测定了共聚物及其载药胶束的细胞毒性.结果证实硬脂酸和叶酸均已接枝在白芨多糖上.疏水性药物多西他赛可被包嵌于FA-BSPs-SA的胶束内.叶酸取代度增加,胶束粒径减小,载药量与包封率均增加.载药胶束体外释药具有p H依赖性(p H=5.0~7.4).共聚物FA-BSPs-SA和BSPs-SA浓度为40μg/m L时,细胞存活率均在80%以上.与多西他赛溶液相比,相同药物浓度的FA-BSPs-SA和BSPs-SA载药胶束抗肿瘤效果更佳,且载药FA-BSPs-SA胶束对有叶酸受体表达的肿瘤细胞的抑制作用较载药BSPsSA胶束更强.FA-BSPs-SA共聚物有望作为难溶性抗肿瘤药物的纳米载体材料.     

基于“分子胶”的新型两亲性嵌段共聚物β-CD-PLA的合成及其胶束化

以二重氢键为引导,二硫键连接疏水性聚乳酸(PLA)和亲水性β-环糊精(β-CD)合成了嵌段共聚物β-CD-PLA。采用1 H-NMR和GPC对嵌段共聚物β-CD-PLA的结构进行了表征,以芘作为荧光分子探针对嵌段共聚物β-CD-PLA自组装胶束的性质进行了表征,采用动态光散射纳米粒度仪(DLS)对自组装胶束的粒径进行了测试。结果表明:在二重氢键的引导作用力和碘的氧化作用下,中间体脱去保护基形成双二硫键,形成目标嵌段共聚物β-CD-PLA,该嵌段共聚物能够在水中自组装形成纳米胶束,临界胶束浓度(CMC)为0.089mg/mL,在稀溶液中具有良好的稳定性,自组装形成空白胶束的粒径为31nm,阿霉素盐酸盐(DOX)载药胶束的粒径为42nm。     

肝素杂化材料的制备及抗凝血性质的初步研究

以甲苯二异氰酸酯(TDI)中的-NCO基与纳米金属氧化物表面的羟基发生反应,得到改性纳米金属氧化物,并使其与肝素钠(Heparin)进行接枝反应生成肝素杂化材料,结合红外、热重、扫描电镜(SEM)等表征方法,确定纳米金属氧化物确实接枝到了肝素钠的表面。通过对体外凝血时间和复钙时间的测定,来初步研究肝素杂化材料的抗凝血性质。结果表明：肝素杂化材料的抗凝血时间和复钙时间均比肝素钠的要短,表明它的抗凝血性比肝素钠的抗凝血性要弱一些;但比纳米金属氧化物和空白组的抗凝血时间和复钙时间要长,说明肝素杂化材料的抗凝血性与其相比则有明显的提高。     

Fabrication of nanomicelle with enhanced solubility and stability of camptothecin based on α,β-poly[(N-carboxybutyl)-l-aspartamide]–camptothecin conjugate

This research is aimed to develop a nanomicelle delivery system in order to enhance the solubility and stability of camptothecin (CPT) in aqueous media. In this case, α,β-poly[(N-carboxybutyl)-l-aspartamide] (PBAsp)–CPT was conjugated by the esterification between PBAsp and 20-OH of CPT, and hence used to fabricate nanomicelles with a particle size between the pore size of blood capillary in normal tissue and that in tumor tissue. It was worthy of note that the drug-loaded system of PBAsp–CPT nanomicelle improved the solubility and stability of CPT in aqueous media. However, with an increase of the CPT loading in PBAsp–CPT, the solubility sharply decreased. Meanwhile, the sizes of PBAsp–CPT nanomicelles showed a tendency of increase. Moreover, the drug release of PBAsp–CPT nanomicelles displayed a linear sustaining profile, and hence resulted in the essential decrease of cytotoxicity to L929 cell line. The assembled nanomicelles based on the PBAsp–CPT conjugates showed a great potential as polymer prodrug of tumor therapy, and the controlled nano-scale might achieve the passive tumor targeting.     

Synthesis,self-assembly,and pH-responsive drug release of PHMEMA-PEG-PHMEMA ABA triblock copolymers

Abstract

A series of tertiary amine containing PHMEMA-PEG-PHMEMA ABA triblock copolymers were synthesized by atom transfer radical polymerization (ATRP) using bromine-capped poly(ethylene glycol) (Br-PEG-Br) and 2-(hexamethyleneimino)ethyl methacrylate (HMEMA) as macro-initiator and monomers, respectively. The chemical structures and molecular weights of triblock copolymers were characterized by ¹H NMR and gel permeation chromatography (GPC). The self-assembly behaviors of copolymers in different pH conditions were studied by dynamic light scattering (DLS) and transmission electron microscopy (TEM). Triblock copolymers self-assembled into micelles in water (pH 7.4) and the micelles disassembled at acidic pH (pH 5.0). Anticancer drug doxorubicin (DOX) was used as a drug model and physically encapsulated into polymeric micelles. The drug release of DOX-loaded polymeric micelles was pH-responsive; the drug-loaded micelles that had higher contents of tertiary amine in polymer pendant groups showed faster release speed. In addition, the drug-loaded micelles showed excellent inhibition efficacy against HeLa cells in vitro.     

Self-assembled micellar nanoparticles of a novel star copolymer for thermo and pH dual-responsive drug release

An amphiphilic star block copolymer comprised of a hydrophobic PMMA block and a hydrophilic tri-arm poly(NIPAAm-co-DMAEMA) block was synthesized by copolymerization of NIPAAm and DMAEMA, with Ce(4+) ions and tris(hydroxymethyl)methylamine as a redox initiatory system. The star copolymer undergoes self-assembly to the micellar nanoparticles with a core-shell structure and the thermo/pH dual-response, originated from the thermo-sensitivity of PNIPAAm and the pH-sensitivity of PDMAEMA. A fluorescence probe study showed the pH-dependent low CMCs (7.5 to 11.2 mg/L) of the micelles, confirming the formation of stable micelles. Morphological investigations showed that the blank and drug-loaded micelles both had spherical and uniform shapes. The sizes of the blank and drug-loaded nanoparticles were between 80 and 120 nm, depending on the given pH. The LCSTs of the star copolymer were determined to be 32 degrees C, 36.6 degrees C and 39.5 degrees C, corresponding to pH 5, pH 7.4 and pH 9, respectively, demonstrating a pH-dependent thermo-response. As a drug delivery, the micellar nanoparticles showed the dual-responsive release profiles in vitro, which were confirmed by the drug release studies. The obtained results showed the thermo-triggered accelerated release at pH 7.4, and the pH-triggered accelerated release at 37 degrees C, indicating the micelles nanoparticles would be a promising site-specific drug delivery for enhancing the accumulation of drug in targeting pathological areas.     

具有温敏性的混合胶束的制备与表征及药物体外释放

通过原子转移自由基聚合(ATRP)合成了以胆固醇为端基的两亲性聚(N-异丙基丙烯酰胺)(Chol-PNIPAAm),利用FTIR、1H-NMR和GPC等方法表征了聚合物的结构.将该两亲性温敏聚合物与聚乙二醇单甲醚硬脂酸酯(mPEG-SA)通过简单混合,即可得到稳定的Chol-PNIPAAm/mPEG-SA混合胶束体系....     

Methotrexate-loaded biodegradable polymeric micelles: preparation, physicochemical properties and in vitro drug release

Polymeric micelles based on amphiphilic diblock copolymers methoxy poly(ethylene glycol)-polylactide with various hydrophobic lengths were designed as carriers of poorly water-soluble anticancer drug methotrexate (MTX). Relationship between physicochemical characteristics of micelles and release behavior was explored. The critical micelle concentration was determined by fluorescence spectroscopy using 9-chloromethyl anthracene as fluorescence probe. Core-shell type polymeric micelles were prepared by free-surfactant dialysis technique. The mean size of micelles loaded with MTX was 50-200 nm with narrow polydispersity. Physicochemical properties of drug-loaded micelles were evaluated. In vitro release behavior of MTX was also investigated. MTX was continuously released from micelles and less than 50% MTX was released in 5 days. Release rate was dependent on chemical structures of micelles and enhanced by decreasing polylactide lengths.     

Star‐shaped nanomicelles of polyisobutylene‐polystyrene diblock copolymers. New stabilizer for living dispersion polymerization of styrene

Formation of star‐shaped nanomicelles of polyisobutylene‐polystyrene (PIB‐PS) diblock copolymers in hexane solution is reported. The length of the polystyrene segments were varied in the M_n range of 4000‐13000 g/mol at approximately constant polyisobutylene segments length. The size and the size distribution of the nanomicelles were investigated by dynamic light scattering. Based on static light scattering measurements the mass‐average molecular mass of the micelles and the number of arms were also determined. The synthesized diblock‐copolymers were demonstrated to be capable of stabilizing the growing particles which were formed in the living anionic dispersion polymerization of styrene in hexane.     

Dual-response nanocarrier based on graft copolymers with hydrazone bond linkages for improved drug delivery

Core–shell micelles with biodegradability, thermo- and pH-response were successfully demonstrated by poly(2-oxepane-1,5-dione-co-ɛ-caprolactone) (P(OPD-co-CL)) grafted with hydrophilic segments of amine-terminated poly(N-isopropylacrylamide) (At-PNIPAM). To compare with the graft copolymer, P(OPD-co-CL) block PNIPAM polymer was also prepared. The micelles with core–shell structure were formed with both graft and block copolymers by self-assembly in aqueous solutions, of which PNIPAM shell is thermo-response. Furthermore, P(OPD-co-CL)-g-PNIPAM also showed pH-sensitivity, which was attributed to the acid-cleavable property of the hydrazone bond. The low critical micelle concentrations (CMCs) of graft polymers and block polymers were 6.7 mg/L and 14.3 mg/L, respectively, which indicated the formation of stable micelles. Both drug-free and drug-loaded micelles were in uniformly spherical shape observed by transmission electron microscopy (TEM). The sizes of the drug-free and drug-loaded micelles prepared from graft polymer were 123.5 nm and 146.5 nm, respectively, and the sizes of those prepared from block polymer were 197.5 nm and 211.5 nm, respectively. The lower critical solution temperature (LCST) for the graft polymer was 34.3 °C, while that for the block polymer was 28.1 °C, demonstrating a thermo-response. The graft polymeric micelles exhibited thermo-triggered decelerated release at pH 7.4, and pH-triggered accelerated release at 25 °C in vitro release test, indicating that the graft polymeric micelles could be a promising site-specific drug delivery system for enhancing the bioavailability of the drug in targeted pathological areas.     

垃圾渗沥液中难降解有机污染物的Fenton混凝处理

垃圾渗沥水;上流式厌氧污泥床;废水处理;垃圾渗沥液中难降解有机污染物的Fenton混凝处理     

肝素抗凝血浆与血清中微量元素测定的对比分析

目的研究肝素抗凝血浆代替血清进行微量元素测定的可行性。方法选择2014年6月在汉川市人民医院接受生化检验的272例患者,采用Beckman DXC800型全自动生化分析仪,同时检测患者的肝素抗血浆和血清中锌(Zn)、铁(Fe)、铜(Cu)3种微量元素的浓度。结果肝素抗凝血浆锌、铁与血清中的锌、铁离子浓度比较无显著差异,差异无统计学意义(P0.05);血浆中铜离子的浓度明显低于血清中铜离子的检测值,差异有统计学意义(P0.05),但通过回归方程可以校正。结论肝素抗凝检测方法能够有效避开血液的凝固过程,在短时间内分离标本并检测,从而减少放置误差。但肝素抗凝血浆铜的检验还应进行回归校正。     

In vitro evaluation of cellulose acetate hemodialyzer immobilized with heparin

In this study, heparin was immobilized onto cellulose acetate hollow fibers to improve the anticoagulation performance during hemodialysis. In vitro evaluation was carried out using mini‐hemodialyzer circulating with fresh porcine whole blood to simulate kidney therapy. The dialysis performance and hemocompatibility were estimated. The results showed that heparinized hemodialyzer could be used through out the whole dialysis time (4 hr) without injecting additional heparin to prevent coagulation in the dialysis system. In addition, the hemocompatibility was evaluated by measuring activated partial thromboplastin time (APTT), prothrombin time (PT), and fibrinogen time (FT). The complete blood count (CBC) including red blood cell (RBC), hemoglobin (Hgb), hematocrit (Hct), white blood cell (WBC), and platelet were determined. The results showed that heparinization could keep the CBC stable during dialysis, whereas unmodified cellulose acetate hemodialyzer would cause a decrease in RBC unless heparin was injected during dialysis. Heparinized hemodialyzer showed longer APTT, PT, and FT than unmodified hemodialyzer. Heparinized hemodialyzer also showed slightly higher clearance than unmodified hemodialyzer. These results indicated that the dialysis performance and hemocompatibility of cellulose acetate hemodialyzer could be improved by the immobilization of heparin. Copyright © 2006 John Wiley & Sons, Ltd.