pH敏感释药两亲性壳聚糖共聚物胶束的制备及其性质考察

目的在合成了两亲性接枝共聚物丁酰基-羧甲基-壳聚糖(butyryl-carboxymethyl-chitosan,BR-CM-CS)的基础上,采用化学键合载药方式结合透析法制备了阿霉素pH敏感两亲性共聚物胶束并对其相关性质进行考察。方法利用芘荧光探针技术测定胶束的临界胶束浓度(CMC);通过透析法结合紫外分光光度法测定胶束的载药量及包封率;分别利用透射电镜(TEM)、扫描电镜(SEM)、动态光散射法(DLS)和zeta电位分析仪对胶束及其冷冻干燥产品的形态、粒径和表面电位进行了表征;采用透析法考察了载药聚合物胶束的体外释放行为。结果胶束的CMC值为1.0 mg.L-1,载药量可达12.5%,包封率为89.1%;胶束的粒度分布很窄,平均粒径为205.2 nm;胶束粒子为类球形且分散良好,其表面zeta电位值为25.94 mV;胶束释药行为体现pH敏感性。结论以壳聚糖为载体的化学腙键释药胶束作为抗肿瘤药物的传递系统具有可行性及良好的应用前景。     

多西他赛pH敏感型聚(2-乙基-2-噁唑啉)-聚(D,L-丙交酯)自组装胶束的制备及其性质

目的利用两亲性嵌段共聚物聚(2-乙基-2-噁唑啉)-聚(D,L-丙交酯)[poly(2-ethyl-2-oxazo-line)-poly(D,L-lactide),PEOz-PDLLA]的自组装性能制备pH敏感型多西他赛胶束,并对其相关性质进行考察。方法运用阳离子开环聚合反应得到PEOz-PDLLA,通过FITR、1H-NMR和凝胶色谱法对其结构进行表征,采用电位滴定法测定共聚物pKa,应用荧光探针技术确定临界胶束浓度(criticalm icelle concentration,CMC)。动态光散射法和Zeta电位测试仪测定胶束的粒径和Zeta电位。以薄膜分散法包载多西他赛,并用透析法研究载药胶束的体外释放度。结果PEOz-PDLLA的亲水/疏水段分子质量比值为0.76,pKa为6.41,CMC为0.8×10-3g.L-1。载药胶束包封率为94.9%、载药量质量分数为8.7%、平均粒径为(35.3±4.9)nm、Zeta电位为(25.51±2.14)mV,在pH5.0的释放介质中释药速度加快。结论PEOz-PDLLA嵌段共聚物可自组装形成胶束,高效包载多西他赛,体外释放具有pH敏感性。     

聚(2-乙基-2-噁唑啉)修饰超氧化物歧化酶模拟物脂质体冻干制剂的制备

目的:制备聚(2-乙基-2-噁唑啉)(PEOZ)修饰超氧化物歧化酶(SOD)模拟物脂质体的冻干制剂。方法:通过考察预冻方式、预冻时间、真空干燥时间及联合冻干保护剂的种类及比例等优化冻干工艺,并测定所制制剂的水化复溶时间、粒径和包封率。结果:以10%乳糖+1%甘露醇+10%海藻糖作为联合冻干保护剂,并以外加方式加入PEOZ修饰SOD模拟物脂质体中,快速冷冻5h,真空干燥30h,可得到外观光洁、平整的目标冻干制剂;其水化复溶时间为(10±1)s,粒径为(159.3±10.2)nm,包封率为86.25%(RSD=3.26%,n=6)。结论:该优化冻干工艺质量可控,重复性好。     

紫杉醇pH敏感聚合物胶束的制备与评价

摘 要 目的：合成双嵌段共聚物材料聚（2-乙基-2-噁唑啉）-聚乳酸（PEOz-PLA）,制备紫杉醇pH敏感嵌段共聚物胶束,并对其体外性质进行评价。方法: 用¹ HNMR和红外光谱对聚合物结构进行表征,采用透析法制备紫杉醇载药胶束,对冻干胶束的冻干保护剂种类进行筛选,芘荧光探针法测定胶束的临界胶束浓度（CMC）,动态光散射法（DLS）对胶束的粒径分布进行测定,透析法测定载药胶束在不同pH条件下的体外释药行为。结果: 胶束的临界胶束浓度为25.63 mg·ml^-1,以10% 聚乙二醇4000作为冻干保护剂胶束复溶性好,粒径分布窄,胶束载药量为8.12%,包封率为69.33%,冻干胶束平均粒径为183.7 nm;在 pH 7.4释放介质中,胶束释药缓慢,而在pH 5.0条件下,胶束释药速率明显加快,体现出胶束释药行为的pH敏感性。结论: PEOz PLA 聚合物胶束制备工艺简单,其粒径、包封率和载药量可控,具有一定的缓释作用,为其进一步的药理与临床应用提供依据。     

温度/pH双敏感嵌段共聚物胶束的体外性质研究

本文采用透析法制备了新型温度/pH双敏感聚组氨酸-聚乳酸羟基乙酸-聚乙二醇-聚乳酸羟基乙酸-聚组氨酸(PHis-b-PLGA-b-PEG-b-PLGA-b-PHis)嵌段共聚物的空白胶束与阿霉素(DOX)载药胶束。采用荧光探针技术测定其临界胶束浓度(CMC);应用光透射法研究了聚合物胶束的温度和pH敏感性质;测定了阿霉素载药胶束的粒径、形态、包封率和载药量;并对阿霉素载药胶束的温度和pH响应释药行为进行了研究。结果表明,制备的嵌段共聚物的临界胶束浓度为7.5×10-3 g.L-1;随胶束溶液温度升高或pH降低,其透光率升高;载药胶束的包封率为(85.2±3.1)%,载药量为(10.4±4.5)%;载药胶束粒径为(91.1±15.8)nm,为类球形结构;与模拟生理条件下(37℃,pH 7.4)释药行为相比,升高温度(41℃)、降低pH(pH 7.0、pH 6.5、pH 5.0)和同时升温并降低pH(41℃,pH 5.0)后胶束释药行为明显加快,表明该胶束的释药行为具有温度和pH敏感性。研究结果可见,PHis-b-PLGA-b-PEG-b-PLGA-b-PHis共聚物胶束具有pH/温度双重响应性质,有望成为抗肿瘤...     

阿霉素-五味子乙素pH敏感聚合物胶束的制备与制剂学性质

目的以p H敏感聚合物聚乙二醇-聚乳酸-聚组氨酸[poly(ethyleneglyco1)-poly(D,L-lactide)-poly(L-histidine),m PEG-PLA-PHis]胶束为载体,联合包载抗肿瘤药物阿霉素与多药耐药逆转剂五味子乙素制备聚合物胶束,并对其制剂学性质进行研究。方法采用薄膜分散法制备阿霉素-五味子乙素p H敏感聚合物胶束,以包封率、载药量和稳定性(载药胶束24 h的包封率和载药量变化)为评价指标,采用单因素试验及Box-Behnken效应面法筛选最优处方;应用透射电子显微镜观察载药胶束的外观形态,动态光散射法测定载药胶束的粒径及zeta电位;透析法考察载药胶束在不同p H条件下的释药行为。结果制备的阿霉素-五味子乙素p H敏感聚合物胶束平均粒径为64.73 nm,zeta电位为-8.7 m V。最优处方中阿霉素包封率为95.3%,载药量为8.7%,五味子乙素包封率为76.1%,载药量为3.4%,载药胶束稳定性较好。体外释放结果表明,所制备的阿霉素-五味子乙素p H敏感聚合物胶束在弱酸性条件下,药物释放速率明显加快。结论采用星点设计-效应面法优化处方与制备工艺,所制备的阿霉素-五味子乙素p H敏感聚合物胶束粒径分布均匀,包封率和载药量良好,具有明显的p H响应行为。     

阿霉素共聚物胶束的制备及体外性质研究

目的制备阿霉素共聚物胶束并研究其体外性质。方法采用开环聚合法合成聚乙二醇单甲醚-聚乳酸羟基乙酸（mPEG—PLGA）嵌段共聚物;用透析法、溶剂蒸发法制备空白及载阿霉素胶束;动态光散射仪（DLS）测定其粒径分布;采用紫外分光光度法测定胶束的包封率和载药量。通过体外释药实验研究了载阿霉素胶束的释药特性。结果采用透析法制备载阿霉素胶束大小均匀,平均粒径为（91．1±15．8）nm;药物胶束的包封率为85．2％,载药量为10．4％;与市售阿霉素注射剂相比,载阿霉素胶束具有良好的缓释性能。结论共聚物胶束可作为疏水性药物阿霉素的载体。     

阿霉素温度/pH双敏型自组装嵌段共聚物胶束的制备

本文用透析法制备了新型温度/pH双敏自组装嵌段共聚物聚组氨酸-聚乳酸羟基乙酸-聚乙二醇-聚乳酸羟基乙酸-聚组氨酸 (OLH-b-PLGA-b-PEG-b-PLGA-b-OLH) 胶束, 采用荧光探针技术测定其不同温度下临界胶束浓度 (CMC); 用透析法测定共聚物胶束的包封率和载药量; 对胶束的粒径、形态和表面电位进行考察, 并对阿霉素胶束的体外释药和pH敏感性进行了研究。CMC介于0.022 4～0.001 7 μg·mL⁻¹, 胶束包封率为92.8%, 载药量为15.7%; 载药胶束粒径为 (61.7 ± 13.4) nm, zeta电位为−9.88 mV; 阿霉素的体外释药速率随pH降低 (pH 7.4～5.0) 而增加。结果表明, 胶束的CMC随温度升高而降低, 体外释药具有明显的pH敏感性, 该载体材料作为抗肿瘤药物的靶向传递系统具有较好的应用前景。     

多西他赛pH敏感嵌段共聚物胶束的制备

本文在合成pH敏感两亲性嵌段共聚物聚(2-乙基-2-噁唑啉)-聚乳酸(PEOz-PDLLA)的基础上，采用薄膜分散法制备多西他赛pH敏感嵌段共聚物胶束，利用芘荧光探针技术测定胶束的临界胶束浓度(CMC)；通过高效液相色谱测定胶束的载药量及包封率；分别利用透射电镜、动态光散射法和zeta电位分析仪对胶束的形态、粒径和表面电位进行了表征；采用透析法考察了载药聚合物胶束的体外释放行为。结果表明，胶束的临界胶束浓度值为1.0×10^-3 g·L^-1；载药量可达15.0%，包封率为91.1%；胶束的粒度分布很窄，平均粒径为28.7nm；胶束粒子为圆球形且分散良好，其表面zeta电位值为(1.19±0.12)mV；在pH 7.4释放介质中，多西他赛胶束具有缓释作用；而在pH 5.0条件下，胶束释药明显加快，体现出PEOz-PDLLA胶束释药行为的pH敏感性。综合上述研究可见，PEOz-PDLLA嵌段共聚物胶束作为疏水性抗肿瘤药物的给药系统具有很好的应用前景。     

紫杉醇pH敏感嵌段共聚物胶束的制备与体外评价

目的应用pH敏感聚组氨酸-聚乳酸-聚乙二醇(poly(L-histidine)-poly(D,L-lactide)-poly(ethylene glycol),PHis-PLA-mPEG)聚合物为载体材料,采用溶剂挥发法制备紫杉醇pH敏感嵌段共聚物胶束,并对其体外性质进行评价。方法采用芘荧光探针法测定PHis-PLA-mPEG聚合物的临界胶束浓度(critical micelle concentration,CMC);超速离心法测定紫杉醇共聚物胶束的包封率和载药量;分别利用动态光散射法和Zeta电位分析仪对胶束的粒径分布和表面电位进行测定;采用透析法测定载药胶束在不同pH条件下的体外释药行为。结果 PHis-PLA-mPEG临界胶束质量浓度为8.9 mg·L-1,胶束载药量质量分数为8%;包封率可达90%以上;载药胶束的平均粒径为150.2nm,PDI为0.097,粒度分布较窄,Zeta电位为-14.3 mV;载药胶束在弱酸性条件下,药物释放行为明显加快。结论 PHis-PLA-mPEG聚合物载体材料具有较好的pH敏感释药行为,其作为抗肿瘤药物的靶向传递系统具有较好的应用前景。     

Preparation and in vitro characterization of paclitaxel-loaded pH-responsive polymeric micelles based on poly(2-ethyl-2-oxazoline)-vitamin E succinate

To ensure the delivery of antitumor drugs to tumor site and quick release in tumor cells, we designed and prepared pH-sensitive polymeric micelles by combining cationic ring-opening polymerization of 2-ethyl-2-oxazoline (EOz) with vitamin Esuccinate (VES), and then encapsulating paclitaxel (PTX) into the micelles self-assembled by poly(2-ethyl-2-oxazoline)-vitamin E succinate (PEOz-VES). The structure of the synthesized PEOz-VES was confirmed by ¹H NMR spectrum, and the molecular weight measured by GPC was 1212 g/mol. The pK_a of PEOz-VES with a low critical micelle concentration of (5.84±0.02) mg/L was determined to be 6.01. The PTX-loaded PEOz-VES polymeric micelles prepared by film hydration method were characterized to have a nanoscaled size of about 30 nm in diameter, a positive Zeta potential of 4.86 mV and uniform spherical morphology by TEM observation. The drug loading content and encapsulation efficiency were (2.63±0.16)% and (84.1±3.38)%, respectively. The in vitro release behavior of PTX from PEOz-VES micelles in PBS displayed pH-dependent pattern and was gradually accelerated with decrease of pH value, implying that the micelles could distinguish endo/lysosomal pH and tumor extracellular pH from physiological pH by accelerating drug release. Therefore, the designed PEOz-VES micelles might have significant promise for anti-cancer drug delivery.     

Folate-modified poly(2-ethyl-2-oxazoline) as hydrophilic corona in polymeric micelles for enhanced intracellular doxorubicin delivery

The transmembrane transport of drug loaded micelles to intracellular compartment is quite crucial for efficient drug delivery. In the current study, we investigated the cellular internalization and anticancer activity of doxorubicin loaded micelles with folate modified stealthy PEOz corona. Folate-decorated micelles incorporating doxorubicin were characterized for particle size, degree of folate decoration, drug loading content and encapsulation efficiency, morphology, and surface charge. The targeting capability and cell viability were assessed using HeLa, KB, A549 and MCF-7/ADR cell lines. In vitro study clearly illustrated the folate receptor (FR) mediated targeting of FA modified micelles to FR-positive human HeLa, KB and MCF-7/ADR cells, while specific delivery to FR-negative A549 cells was not apparently increased at the same experimental conditions. Cytotoxicity assay showed 60% and 58% decrease in IC₅₀ values for HeLa and KB cells, while only a slight decrease for A549 cells, following treatment with folate modified formulations. The enhanced intracellular delivery of FA modified micelles in MCF-7/ADR cells was also observed. In vivo antitumor tests revealed DOX entrapped FA-PEOz-PCL micelles effectively inhibited the tumor growth and reduced the toxicity to mice compared with free DOX. The current study showed that the targeted nano-vector improved cytotoxicity of DOX and suggested that this novel PEOz endowed stealthy micelle system held great promise in tumor targeted therapy.     

聚（2-乙基-2-噁唑啉）-聚乳酸胶束的血液相容性和细胞相容性研究

合成的二嵌段共聚物聚（2-乙基-2-噁唑啉）-聚乳酸（PEOz-PLA）可自组装形成胶束,其在药物输送领域的应用与口俱增。然而,其与血液和细胞之间的相互作用迄今未知。本研究拟对PEOz-PLA胶束的血液相容性和细胞相容性进行评价,为PEOz-PLA胶束的潜在应用提供数据支持。通过溶血、凝血时间、血小板激活以及与白蛋白的相互作用评价了PEOz-PLA胶束的血液相容性。结果表明,PEOz-PLA胶束的血液相容性良好。SRB的实验结果表明,PEOz-PLA胶束与KBv细胞孵育后并未出现明显的细胞毒性,显示出良好的细胞相容性。总之,PEOz-PLA胶束是血液和细胞相容的药物载体,可用于静脉给药。     

Environmental-sensitive micelles based on poly(2-ethyl-2-oxazoline)-b-poly(L-lactide) diblock copolymer for application in drug delivery

Anticancer drug doxorubicin (DOX) was physically loaded into the micelles prepared from poly(2-ethyl-2-oxazoline)-b-poly(L-lactide) diblock copolymers (PEOz-PLLA). PEOz-PLLA consists of hydrophilic segment PEOz and hydrophobic segment PLLA showed pH-sensitivity in the aqueous solution. The DOX-loaded micelle exhibited a narrow size distribution with a mean diameter around 170 nm. The micellar structure can preserve hydrophobic drug DOX under the physiological condition (pH 7.4) and selectively release DOX by sensing the intracellular pH change in late endosomes and secondary lysosomes (pH 4-5). At 37 degrees C, the cumulated released rate of DOX from micelles was about 65% at pH 5.0 in the initial 24 h. Additionally, polymeric micelles had low cytotoxicity in human normal fibroblast HFW cells for 72 h by using MTT assay. Moreover, DOX-loaded micelles could slowly and efficiency decrease cell viability of non-small-cell lung carcinoma CL3 cells. Taken together, PEOz-b-PLLA diblock polymeric micelles may act as useful drug carriers for cancer therapy.     

Antitumor activity of adriamycin-incorporated polymeric micelles of poly(gamma-benzyl L-glutamate)/poly(ethylene oxide)

The multiblock copolymer composed of poly(gamma-benzyl L-glutamate) (PBLG) and poly(ethylene oxide) (PEO) was synthesized to prepare polymeric micelles as an anticancer drug carrier. Adriamycin (ADR) used as an anticancer drug was incorporated into the polymeric micelles prepared by the multiblock copolymer. The higher the drug feeding ratio, the higher the drug loading contents and the lower the drug loading efficiency. The increased drug feeding ratio resulted in increased particle sizes. At all of the formulations, particle sizes were less than 150 nm. The particles were observed as spherical shapes. ADR release from ADR-loaded polymeric micelles in vitro was decreased with an increased drug loading contents. In in vitro antitumor activity test using CT 26 tumor cells, polymeric micelles showed almost similar cytotoxicity when compared to ADR itself while polymeric micelles themselves did not affect cytotoxicity. In in vivo antitumor activity test using mice tumor xenograft model, the polymeric micelles showed improved survivability of mice with minimized weight changes and excellent tumor growth suppression efficacy. Polymeric micelles of the multiblock copolymer suggested to be a good candidate for anticancer drug delivery carrier.     

Encapsulation of amphotericin B in poly(ethylene glycol)-block-poly(epsilon-caprolactone-co-trimethylenecarbonate) polymeric micelles

The aim of this work was to evaluate the potential of self-assembling poly(ethyleneglycol)(750)-block-poly(epsilon-caprolactone-co-trimethylenecarbonate)(4500) 50/50 copolymers (PEG-p(CL-co-TMC)) to solubilize amphotericin B in polymeric micelles and to disaggregate the drug to the less toxic monomeric form. Amphotericin B was encapsulated in the micelles upon dilution of a mixture of the liquid polymer and the drug in water. Its solubility was increased by two orders of magnitude depending on polymer concentration. The aggregation state of amphotericin B was decreased by PEG-p(CL-co-TMC). The preparation method and the loading of the polymeric micelles influenced it. The antifungal activity of the drug was reduced by encapsulation in the polymeric micelles whereas the onset of amphotericin B-induced hemolysis was delayed. PEG-p(CL-co-TMC) micelles could be an easy method for amphotericin B encapsulation.     

Intelligent polymeric micelles from functional poly(ethylene glycol)-poly(amino acid) block copolymers

This review describes our recent efforts on the design and preparation of intelligent polymeric micelles from functional poly(ethylene glycol)-poly(amino acid) (PEG-PAA) block copolymers. The polymeric micelles feature a spherical sub-100 nm core-shell structure in which anticancer drugs are loaded avoiding undesirable interactions in vivo. Chemical modification of the core-forming block of PEG-PAA with a hydrazone linkage allows the polymeric micelles to release drugs selectively at acidic pH (4-6). Installation of folic acids on the micelle surface improves cancer cell-specific drug delivery efficiency along with pH-controlled drug release. These intelligent micelles appear to be superior over classical micelles that physically incorporate drugs. Studies showed both controlled drug release and targeted delivery features of the micelles reduced toxicity and improved efficacy significantly. Further developments potentiate combination delivery of multiple drugs using mixed micelles. Therefore clinically relevant performance of the polymeric micelles provides a promising approach for more efficient and patient-friendly cancer therapy.     

Preparation and characterization of intestinal transporter-targeted polymeric micelles

The intestinal epithelium is the main barrier to the oral delivery of poorly water-soluble drugs. Based on the specific transporters expressed on the apical membrane of the intestinal epithelium, novel polymer micelles targeting to the organic cation transporter 2 (OCTN2) were constructed by combining carnitine conjugated poly(2-ethyl-2-oxazoline)-poly(D,L-lactide) (Car-PEOz-PLA) with monomethoxy poly(ethylene glycol)-poly(D,L-lactide) (mPEG-PLA). The structure of the synthesized Car-PEOz-PLA was confirmed by ¹H NMR, TLC and ammonium reineckate precipitation reaction, and the number-average molecular weight determined by GPC was 7260 g/mol with a low PDI of 1.44. Coumarin 6-loaded carnitine modified polymeric micelles prepared by film hydration method were characterized to have a nano-scaled size of about 31 nm in diameter, uniform spherical morphology, high drug loading content of 0.098%±0.03% and encapsulation efficiency of 92.67%±2.80%. Moreover, the carnitine-modified micelles exhibited the similar in vitro release behavior in SGF and SIF, and evidently enhanced intestinal absorption of poorly water-soluble agent. Therefore, the designed OCTN2-targeted micelles might have a promising potential for oral delivery of poorly water-soluble drugs.     

Drug release from thermo-responsive self-assembled polymeric micelles composed of cholic acid and poly(N-isopropylacrylamide)

Cholic acid, conjugated with amine-terminated poly(N-isopropylacrylamide) (abbreviated as CA/ATPNIPAAm), was synthesized by a N, N'-dicyclohexyl carbodiimide (DCC)-mediated coupling reaction. Self-assembled CA/ATPNIPAAm micelles were prepared by a diafiltration method in aqueous media. The CA/ATPNIPAAm micelles exhibited a lower critical solution temperature (LCST) at 31.5 degrees C. Micelle sizes measured by photon correlation spectroscopy (PCS) were approximately 31.6+/-5.8 nm. The CA/ATPNIPAAm micelles were spherical and their thermal size transition was observed by transmission electron microscope (TEM). A fluorescence probe technique was used for determining the micelle formation behavior of CA/ATPNIPAAm in aqueous solutions using pyrene as a hydrophobic probe. The critical micelle concentration (CMC) was evaluated as 8.9 x 10(-2) g/L. A drug release study was performed using indomethacin (IN) as a hydrophobic model drug. The release kinetics of IN from the CA/ATPNIPAAm micelles revealed a thermo-sensitivity by the unique character of poly(N-isopropylacrylamide) i.e. the release rate was higher at 25 degrees C than at 37 degrees C.     

Novel polymeric micelles for hydrophobic drug delivery based on biodegradable poly(hexyl-substituted lactides)

Novel amphiphilic methoxy-poly(ethylene glycol)-poly(hexyl-substituted lactides) block copolymers were synthesized by ring-opening polymerization (ROP) of mono and dihexyl-substituted lactide (mHLA and diHLA) in bulk at 100 degrees C in the presence of tin(II) 2-ethylhexanoate (Sn(Oct)(2)) as catalyst and methoxy-poly(ethylene glycol) (MPEG) as initiator. MPEG-PmHLA and MPEG-PdiHLA copolymers of predictable molecular weights and narrow polydispersities were obtained, as shown by (1)H NMR and GPC. DSC experiments showed that the MPEG-PHLA block-copolymer presents a bulk microstructure containing MPEG domains segregated from the PHLA domains. Micelles were successfully prepared from these block copolymers, with sizes ranging from 30 to 80 nm. The critical micellar concentration (CMC) was found to decrease with the increasing number of hexyl groups on the polyester block (MPEG-PLA > MPEG-PmHLA > MPEG-PdiHLA) for copolymers of the same composition and molecular weight. The hydrophobicity of the micelle core in dependence of the number of hexyl groups along the PLA chain was evidenced by absorbance experiments with the incorporation of the dye Nile Red. These novel amphiphilic copolymers are interesting for micellar drug delivery and especially in regard to optimized hydrophobic drug loadings, as it was shown for griseofulvin as a model drug.