肽类树枝状大分子:自组装胶束及药物释放研究

本文以三代聚谷氨酸肽类树枝状分子(G3-Glu)为大分子引发剂,引发N-羧基-L-苯丙氨酸-环内酸酐(NCA-Phe)的开环聚合反应,制备聚谷氨酸树枝状大分子-聚苯丙氨酸嵌段共聚物.嵌段共聚物通过自组装形成以聚苯丙氨酸链段为核,聚谷氨酸树枝状大分子为壳的胶束.将抗肿瘤药物阿霉素负载到高分子胶束中,研究其药物释放性能及体外抗肿瘤效果.结果表明,共聚物胶束具有良好的生物相容性.载药胶束具有药物缓释效果,药物持续释放时间可达60h.载药胶束的体外抗肿瘤实验表明其对肝癌细胞HepG2具有很好的杀灭效果,共培养48h后对癌细胞的杀死率可高达75%.     

主链含酪氨酸的聚磷酸酯抗肿瘤药物的研究

通过含酪氨酸的聚磷酸酯与药物分子进行大分子反应，制备了含５－氟尿嘧啶或氨甲蝶呤的聚磷酸酯。所得聚磷酸酯均具有两亲性，部分聚磷酸酯在水中能形成胶束。研究了这些聚合物的体外降解和释药性能，体外抗肿瘤实验表明，有些聚磷酸酯药物具有较强的抗肿瘤活性。     

双重敏感mPEG-PDPA-P(AAm-co-AN)聚合物自组装体的药物递送

设计合成了一种新型两亲性三嵌段ABC聚合物聚乙二醇单甲醚-聚甲基丙烯酸二异丙胺基乙酯-聚(丙烯酰胺-co-丙烯腈)(mPEG-PDPA-P(AAm-co-AN))。该聚合物具有pH敏感嵌段PDPA和温度敏感嵌段P(AAm-co-AN)，临界溶解温度(UCST)较高，且可以通过改变单体比例来调节UCST。在室温、中性环境下，该聚合物通过自组装形成刺激响应型胶束，可用于抗肿瘤药物的控释研究。温度升高诱导聚合物胶束向不对称囊泡结构转变，pH降低促使聚合物形成更加松散的胶束。在体外释药探究中，聚合物胶束对亲水药物阿霉素(DOX)和疏水药物槲皮素都具有良好的载药效果，在37℃、pH=7.4的条件下泄漏量低，随着温度升高和pH降低，胶束释放药物的速率和释放量明显增加。     

pH敏感两亲性嵌段共聚物胶束的制备及其负载紫杉醇体外药效的研究

采用可逆加成-断裂链转移(RAFT)聚合法,以丙烯酸(AA)、丙烯酸异丁酯(IBA)无规共聚物与聚丙烯酸-2-羟丙酯(PHPA)反应,制备了具有pH敏感性的两亲性嵌段共聚物(P(IBA-co-AA)-b-PHPA).用红外光谱(FTIR)、核磁共振(1H-NMR)、凝胶渗透色谱(GPC)对其结构进行表征.此共聚物在水溶液中可自组装形成胶束,临界胶束浓度约为2.0mg/L.由透射电子显微镜(TEM)、动态光散射(DLS)表征可知胶束为尺寸约100nm的球形颗粒;用DLS观察到胶束粒径随pH值的升高而逐渐增大.以抗癌药物紫杉醇为模型药物,研究载药胶束在模拟人体环境中的控释行为.用CellCountingKit-8(简称CCK-8)法分别研究聚合物胶束对MCF-7人乳腺癌细胞和A549人肺癌细胞的细胞毒性,并评价载药胶束在两细胞中的抗癌效果.结果表明,P(IBA-co-AA)-b-PHPA可作为包载紫杉醇的一种新型纳米材料,载药胶束的体外释放呈明显pH依赖性,且具有较好的体外抗肿瘤活性,有望成为理想的抗肿瘤药物载体.     

具有pH-响应性的聚天冬氨酸类载药胶束的制备和释放能力研究

通过大分子引发剂ω-氨基-α-甲氧基聚乙二醇引发N-羧基-α-氨基环内酸酐开环聚合和水合肼侧基改性,制备了一系列聚乙二醇-聚氨基酸类三嵌段共聚物.其中聚氨基酸链段包括具有酰肼基的聚天冬氨酸衍生物(PAHy),以及疏水性的聚丙氨酸链段.引入具有pH响应性的腙键键合阿霉素,利用键合阿霉素与游离阿霉素之间的π-π叠合作用,在聚合物自组装形成胶束过程中通过化学键合+物理包埋的方式充分负载药物.该胶束以聚丙氨酸链段为核心,以PEG链段为冠层,以PAHy链段为包裹药物的壳层.载药胶束的粒径在170 nm左右.研究不同pH值条件下载药胶束的药物释放能力,随环境pH值的降低药物的释放速率显著增加.     

PPEGMEA-g-PDEAEMA全亲水接枝共聚物的合成及其 包埋甲氨喋呤体外控释的研究

以聚乙二醇丙烯酸酯(PEGMEA)为起始原料, 将原子转移自由基聚合(ATRP)技术和从主干接枝(grafting-from)策略相结合, 合成了结构规整的聚甲基醚聚乙二醇丙烯酸酯-g-聚(N,N’-二乙基胺乙基甲基丙烯酸酯) (PPEGMEA-g- PDEAEMA)接枝共聚物. 这种接枝共聚物通过静电作用形成胶束包埋甲氨喋呤(MTX), 得到具有98.7%高包封率的药物载体, 体外药物释放得到很好的控制.     

温度/pH响应性MPEG-b-PCL/PNVCL-b-PCL共聚物复合胶束的制备及载药性质

以基于亚胺键的嵌段共聚物为构筑单元的温度/pH响应性共聚物复合胶束(CMs), 由于具有亚胺键和核-壳-冠结构, 表现出较高的灵敏度和稳定性. 以聚乙二醇单甲醚(MPEG)、 N-乙烯基己内酰胺(NVCL)和ε-己内酯(ε-CL)为原料, 分别制备了端醛基聚乙二醇单甲醚(MPEG-CHO)、 端醛基聚N-乙烯基己内酰胺(PNVCL-CHO)和端氨基聚己内酯(H₂N-PCL), 利用希夫碱反应, 进一步制备了基于亚胺键的聚乙二醇单甲醚-b-聚己内酯(MPEG-b-PCL)和聚N-乙烯基己内酰胺-b-聚己内酯(PNVCL-b-PCL)嵌段共聚物, 对共聚物结构进行了确认. 以MPEG-b-PCL和PNVCL-b-PCL为构筑单元, 制备了共聚物复合胶束, 研究了复合胶束对阿霉素的包载、 释放性质和细胞毒性等. 研究结果表明, 室温下MPEG-b-PCL和PNVCL-b-PCL能够在水中自组装形成以PCL为核、 MPEG和PNVCL为混合壳的共聚物复合胶束, 在生理温度下, 温敏性PNVCL链段发生相变塌缩在PCL核表面, 能够防止药物扩散释放, 亲水性MPEG链段形成可控通道. 药物体外释放结果表明, 在弱酸性环境中, 亚胺键能够断裂, 胶束被破坏, 促进药物的释放, 噻唑蓝(MTT)实验表明, 复合胶束的细胞毒性较低.     

具有还原刺激响应的聚氨酯胶束的制备和表征

以聚ε-己内酯二元醇(PCL)为软段,赖氨酸二异氰酸酯(LDI)和胱胺(cystamine)为硬段,合成了以胱胺封端的线性聚氨酯预聚体,然后利用α-甲氧基-ω-环氧丙基聚乙二醇(EO-MPEG)的环氧基与胱胺的胺基反应,制备了含有二硫键的双亲性聚氨酯.利用GPC测试了聚氨酯的分子量,1H-NMR及FTIR表征了聚氨酯的结构.利用透析法制备了聚氨酯胶束,荧光探针技术测得其临界胶束浓度为5.6×10-3g/L,TEM分析表明胶束形貌为球形,DLS分析表明胶束的平均粒径为82 nm.还原响应实验表明胶束在10 mmol/L的谷胱甘肽的作用下粒径明显增大,表明胶束具有还原刺激响应特性.最后,以抗肿瘤疏水药物氨甲喋呤(MTX)为模型药物,研究了载药胶束在谷胱甘肽作用下的药物释放,结果表明谷胱甘肽的存在可刺激药物的释放,该材料可作为细胞内还原响应的载体材料使用.     

胶束增强型聚电解质胶囊的结构研究

研究了胶束增强型聚电解质(PAH/PSS和PADA/PSS)胶囊在不同溶液环境中的形貌变化,发现这种新型的胶囊具有迥异于传统聚电解质胶囊的囊壁结构;研究了二维聚电解质复合膜与模板溶解液中嵌段共聚物PS-b-PAA胶束之间的相互作用,发现胶束层可以通过静电力与聚电解质胶囊囊壁相互作用.同时,模拟模板溶出后聚电解质胶囊内部的环境条件,研究了嵌段共聚物胶束在胶囊内部的存在状态及其在透析过程中的变化规律,认为共聚物可以通过疏水作用沉积于聚电解质复合膜的内壁,并通过Ca2+离子的桥联作用稳定,也就是在聚电解质复合膜层基础上又形成了一层胶束层.即这种胶束增强型聚电解质微胶囊的囊壁是由聚电解质层和胶束层所形成的双层结构.用这种双层结构模型,我们合理解释了胶囊在高盐离子浓度下的形貌变化.     

pH敏感新型嵌段共聚物的合成及其对叶酸的运载与释放

采用可逆加成-断裂链转移(RAFT)法,成功合成了一种具有荧光性能的新型p H敏感两亲性嵌段共聚物聚(甲基丙烯酰氧喹啉-co-甲基丙烯酸-2-二甲氨基乙酯)-b-聚(甲基丙烯酸聚乙二醇酯)(P(MAQ-co-DMAEMA)-b-PMAPEG),用红外光谱(FT-IR)、核磁共振(1H NMR)、凝胶渗透色谱(GPC)对其结构进行表征.此共聚物在水溶液中可自组装形成胶束,由扫描电子显微镜(SEM)、动态光散射(DLS)、紫外光谱(UV)和荧光光谱(FL)对聚合物胶束溶液表征可知胶束为尺寸约80 nm的球形颗粒,且胶束溶液具有良好的荧光性.以叶酸(FA)为模型药物,研究载药胶束在模拟人体环境中的控释行为.结果表明:P(MAQ-co-DMAEMA)-b-PMAPEG可作为包载药物的一种新型纳米材料,载药胶束的体外释放呈明显p H依赖性,且具有较好的荧光性,该聚合物有望成为具有荧光性的理想药物载体.     

Comparison of drug delivery properties of PEG-<Emphasis Type="Italic">b</Emphasis>-pdhpc micelles with different compositions

An anti-tumor drug doxorubicin was encapsulated in micelles of poly（ethylene glycol）-b-poly（2,2-dihydroxyl-methyl propylene carbonate）（PEG-b-PDHPC） diblock copolymers.The morphology of both blank micelles and drug loaded micelles was characterized by TEM.The in vitro drug release profiles of micelles were investigated.The cytotoxicity of the micelles was evaluated by incubating with Hela tumor cells and 3T3 fibroblasts.The drug loaded micelles were co-cultured with HepG2 cells to evaluate the in vitro anti-tumor efficacies.The results showed that the mean sizes of both micelles with different copolymer compositions increased after being loaded with drugs.The drug release rate of PEG₄₅-b-PDHPC₃₄ micelles was faster than that of mPEG₁₁₄-b-PDHPC₂₆,micelles.Both of the two block copolymers were non-toxic.The confocal laser scanning microscopy and flow cytometry results showed that both the drug loaded micelles could be internalized efficiently in HepG2 cells.The PEG₄₅-b-PDHPC₃₄ micelles exhibited higher anti-tumor activity comparing to mPEG₁₁₄-b-PDHPC₂₆ micelles.     

Folic Acid Modified Polymeric Micelles for Intravesical Instilled Chemotherapy

In this study,a targeting micellar drug delivery system was developed for intravesical instilled chemotherapy of bladder cancer.The amphiphilic diblock copolymer poly(ε-caprolactone)-block-poly(ethylene glycol) (PCL-b-PEO) with functional amino group (NH2) at the end of PEO block was synthesized.Then the copolymer was conjugated with folic acid (FA) and fluorescein isothiocyannate (FITC) via the PEO-NH2 terminus,and then assembled into micelles with the target moiety and fluorescence labeling.In addition,drug loaded micelles were also fabricated with anticancer drug doxorubicin (DOX) encapsulated in the hydrophobic core.The micelles were characterized in terms of size,drug loaded efficiency and critical micellization concentration (CMC) by means ofDLS,UV and fluorescence spectra.In vitro cellular uptake and cytotoxicity studies showed that FA modified PCL-b-PEO-FA micelles have a greater targeting efficiency to human bladder cancer cell (T-24 cell) compared to PCL-b-PEO-NH2 micelles due to the conjugation of FA on the surface,while no targeting effect to normal tissue originated human embryonic kidney 293 (HEK-293) cells was observed,enabling the micelles a promising drug carrier for intravesical instilled chemotherapy of bladder cancer.     

Self-assembled micelles of novel graft amphiphilic copolymers for drug controlled release

In this study, with the aim of designing an ideal anticancer drug carrier, we synthesized novel amphiphilic graft copolymers, P(Glu-alt-PEG)-graft-PCLA, based on poly(ethylene glycol) (PEG) segments and glutamic acid (Glu) units as the hydrophilic main chain, and poly(?-caprolactone-co-lactide) (PCLA) as hydrophobic branches. The chemical structure of the copolymers was characterized by (1)H MNR and FT-IR. The self-assembly of the copolymers to form micelles was studied by TEM, DLS and fluorescence spectroscopy. In vitro doxorubicin controlled release studies demonstrated that these graft copolymer micelles had high drug loading capacity and good controlled released properties, demonstrating their potential as a novel anticancer drug carrier. The drug loaded graft copolymer micelles exhibited efficient inhibition of HeLa cells in in vitro studies.     

Preparation of poly(glutamic acid) shielding micelles self-assembled from polylysine-b-polyphenylalanine for gene and drug codelivery

A novel amphiphilic cationic block copolymer polylysine-b-polyphenylalanine(PLL-b-PPhe) was synthesized and self-assembled into micelles in aqueous solution,then shielded with poly(glutamic acid)(marked as PG/PLL-b-PPhe) to codeliver gene and drug for combination cancer therapy.Here,doxorubicin(DOX) was selected to be loaded into PLL-b-PPhe micelles and the drug loading efficiency was 8.0%.The drug release studies revealed that the PLL-b-PPhe micelles were pH sensitive and the released DOX could reach to 53.0%,65.0%,72.0% at pH 7.4,6.8 and 5.0,respectively.In order to reduce positive charge and cytotoxicity of PLL-b-PPhe micelles,PG was used as shelding,simultaneously condensed with Bcl2 siRNA to form gene carrier system.Compared with PEI,PG/PLL-b-PPhe had excellent gene transfection efficiency,especially when the molar ratio of PLL to PPhe was 30:60 and the mixed mass ratio of PLL-b-PPhe to gene was 5:1.More importantly,DOX and Bcl2 siRNA gene codelivery system displayed remarkable cytotoxicity against B16 F10 cells.Confocal laser scanning microscopy(CLSM) and flow cytometry were used to characterize endocytosis of the codelivery system,and confirmed that both DOX and Bcl2 siRNA had been endocytosed into B16 F10 cells.The above results indicated that gene and drug codelivery was a promising strategy in future cancer therapy.     

Polypeptide dendrimers: Self-assembly and drug delivery

Amphiphilic dendritic poly(glutamic acid)-b-polyphenylalanine copolymers were synthesized using generation 3 dendritic poly(glutamic acid) as the macroinitiator in the ring-opening polymerization of NCA-Phe.The block copolymers self-assembled micelles with polyphenylalanine segments as core and dendritic poly(glutamic acid) segments as shell.The biocompatibility of the micelles was studied.The release of the anticancer drug doxorubicin from the micelles was investigated in vitro.The results showed that the ...     

共同装载吴茱萸碱和Fe3O4纳米粒子的磁性药物载体的制备

以单甲醚-聚乙二醇-聚（丙交酯-乙交酯）（mPEG-PLGA）作为载体,采用溶液透析的方法共同装载抗癌药物吴茱萸碱和Fe₃O₄ 磁性纳米粒子. 通过透射电子显微镜、红外光谱、紫外-可见光谱及体外释放实验、普鲁士蓝染色、体外毒性实验和磁靶向研究,综合评价了磁性纳米药物载体的性能. 结果表明,磁性药物载体胶束分散性良好,粒径均一,有较高的载药量和包封率,能够实现药物缓释,具有磁靶向特性.     

基于聚(L-谷氨酸)树状分子的智能药物释放系统研究

以天然氨基酸L-谷氨酸为原料,通过收敛法合成了聚(L-谷氨酸)树状分子,通过半胱氨酸将抗肿瘤药物甲氨蝶呤( MTX)键合到聚(L-谷氨酸)树状分子上,构建氧化还原敏感的药物传输系统.用核磁(1H～NMR)等对载体以及载药粒子进行了表征.体外释放研究发现,载药粒子具有良好的氧化还原响应性,在不同浓度的还原剂二硫苏糖醇(D...     

pH敏感型mPEG-Hz-PLA聚合物纳米载药胶束的制备

以合成的含有腙键的聚乙二醇大分子(mPEG-Hz-OH)为引发剂,以丙交酯为单体引发开环聚合反应,并通过调整投料比,制备出3种不同分子量的含腙键的生物可降解嵌段聚合物(mPEG-Hz-PLA).将腙键引入到聚合物的骨架中,以此构建聚合物胶束并作为pH敏感型纳米药物载体.制备的pH敏感型胶束的CMC值等于或低于5.46×10-4 mg/m L,DLS和TEM显示粒径均小于100 nm,且粒径分布均匀.非pH敏感型胶束在不同pH下的粒径变化不明显,而pH敏感型胶束在酸性环境下(pH=4.0和pH=5.0)胶束粒径出现了明显变化.以阿霉素为模型药物制备了pH敏感型载药胶束,其粒径比空白胶束大(100~200 nm),且粒径分布均匀.药物释放实验表明pH敏感型载药胶束随着释放介质pH降低累积释药量增高.MTT实验表明空白胶束对HeLa细胞和RAW264.7细胞几乎没有抑制作用,而载阿霉素的胶束对2种细胞的抑制作用都随着剂量的增大和时间的延长而增强.     

Co-delivery of docetaxel and doxorubicin using biodegradable PEG-PLA micelles for treatment of breast cancer with synergistic anti-tumour effects

Poly(ethylene glycol)-poly(lactic acid) copolymer, prepared by ring opening polymerization, was used as a single platform to co-deliver both hydrophilic doxorubicin and hydrophobic docetaxel (DTX) in a simulated physiological environment. The average size of the negatively charged drug loaded polymeric micelles were found to be 293 nm. The drug loading (%) and encapsulation efficiency (%) were calculated to be 1.21 and 59.0, respectively. The in vitro cytotoxicity test using MCF7 breast cancer cells was conducted using 1 × 10⁴ cells in 10% FBS and 1% antibiotic, and the absorbance of formazan was evaluated at 570 nm. Cell growth inhibition by MTT assay showed viability of 33% of the MCF7 cells after treatment with drug-loaded micelles for 48 h. Controlled release of drugs from the polymeric micelles indicated a burst release effect initially; whereas, 98% of drug could be released at pH 7.4 within a time period of 96 h. Time period for drug release shorten to 48 h only in simulated mild acidic pH (5.4) condition. The in vitro drug release study from micelles indicated synergistic cytotoxicity effect in human metastatic breast cancer MCF7 cell.