壳聚糖纳米粒作为基因载体的研究:粒径对转染效率的影响

研究粒径对壳聚糖(chitosan，CS)纳米粒介导的转染效率的影响。通过调整CS溶液加入质粒基因(plasmid DNA，pDNA)溶液的速度和涡旋时间制备250，580和1 300 nm粒径pDNA/CS纳米粒，研究粒径对CS介导的细胞转染效率的影响。为深入探讨粒径对转染效率的影响，考察了3种粒径pDNA/CS纳米粒的药剂学性质，对抗核酸酶作用和细胞对纳米粒的吸附和摄取行为。结果表明：本文制备的3种粒径纳米粒的药剂学性质和凝聚pDNA的能力等特性基本无差别，均能有效保护pDNA免受核酸酶降解；在HEK293细胞中的转染效率无显著差异；与细胞共孵育4 h，流式细胞仪测定的三者细胞摄取率与摄取量相似；荧光显微图像显示3种粒径纳米粒均以小聚集体形式吸附于细胞表面，激光扫描共聚焦显微图像显示直径约为2 μm小聚集体较易被细胞内吞入胞。因此粒径在250～1 300 nm中对壳聚糖纳米粒介导的细胞转染率基本无影响。     

壳聚糖纳米载体提高抗乙肝免疫核糖核酸免疫活性的研究

目的:通过制备抗乙肝免疫核糖核酸(iRNA)的壳聚糖纳米载体,提高其免疫活性.方法:复凝聚方法制备壳聚糖-免疫核糖核酸纳米粒,扫描电镜、原子力显微镜、Zeta电位/粒度分析仪观察测定壳聚糖-免疫核糖核酸纳米粒形态、粒径和表面电位;核糖核酸酶(RNase)保护试验观察壳聚糖对包裹的iRNA的保护作用;白细胞黏附抑制(LAI)试验测定壳聚糖-免疫核糖核酸纳米粒免疫活性.结果:壳聚糖与iRNA形成表面带正电荷的纳米粒,iRNA未被RNase的降解,白细胞黏附抑制率增高.结论:壳聚糖纳米载体提高了抗乙肝免疫核糖核酸的免疫活性.     

壳聚糖载药纳米粒研究进展

目的介绍壳聚糖载药纳米粒近年来的研究进展。方法总结壳聚糖纳米粒的制备方法、释药特性、生物摄取及其应用。结果不同的制备方法可得到不同粒径和表面特性的壳聚糖纳米粒。壳聚糖纳米粒改变了壳聚糖的摄取机制，广泛应用于药物的器官靶向、DNA转染效率提高、药物的非注射途释给药等方面。结论壳聚糖纳米粒作为一种新型的药物载体，具有重要的研究开发价值。     

载基因壳聚糖纳米粒的制备及其特性的研究

目的制备壳聚糖纳米粒,并连接上质粒,研究壳聚糖纳米粒的特性及其对DNA的结合及保护能力。方法采用离子交联法制备壳聚糖纳米粒,并用喷金扫描电子显微镜检测,了解粒径的分布与形态;通过静电吸附作用连接上pGenesil-1质粒(报告基因);经琼脂糖凝胶电泳分析壳聚糖纳米载体与质粒DNA的结合能力,及不同pH值的壳聚糖纳米粒对质粒DNA的结合能力;并通过DnaseⅠ消化壳聚糖纳米-质粒结合物以观察壳聚糖纳米载体对质粒的保护作用。结果喷金扫描电镜检测证实壳聚糖纳米粒呈均匀分散的球形颗粒,平均直径为5nm;琼脂糖凝胶电泳的结果显示壳聚糖纳米粒能有效地结合载体pGenesil-1质粒;不同pH值的壳聚糖纳米粒对质粒的保护作用不同,当pH值<7时壳聚糖纳米载体能100%结合质粒;DnaseⅠ消化试验证实壳聚糖纳米载体对质粒DNA有保护作用。结论采用离子交联法制备出粒径较小、均匀的壳聚糖纳米粒,并且壳聚糖纳米粒能有效地连接上质粒并对其有保护作用。     

替尼泊苷多层包衣白蛋白纳米粒的制备工艺及体外抗肿瘤活性

目的以人血清白蛋白为载体包载替尼泊苷,经过包衣修饰后制备包载替尼泊苷的多层包衣纳米粒(teniposide-encapsulated multilayer nanoparticles,P-CS-NP),以期降低药物的不良反应并改善其体外抗肿瘤活性。方法以粒径、多分散指数和载药率为评价指标,采用单一因素法筛选出替尼泊苷白蛋白纳米粒的最优处方工艺,通过加入壳聚糖和聚谷氨酸聚乙二醇共聚物进一步制备多层包衣白蛋白纳米粒,筛选得到最优包衣量。以游离的替尼泊苷作为参比,用MTT法测定纳米粒对人肺癌A549细胞的体外细胞毒性,并用流式细胞仪和共聚焦显微镜测定和观察多层包衣纳米粒的细胞摄取率和细胞摄取行为。结果确定了多层包衣纳米粒的处方及制备工艺。多层包衣纳米粒的体外细胞毒性比游离的替尼泊苷小,摄取具有时间依赖性,与壳聚糖共孵育的纳米粒的细胞摄取量增加,入胞后纳米粒主要分布在细胞质。结论白蛋白纳米粒能被壳聚糖和聚谷氨酸聚乙二醇共聚物包衣修饰,多层包衣纳米粒可以作为替尼泊苷的药物递送载体,其体外细胞毒性降低。     

基因壳聚糖纳米粒表面修饰和转染研究

目的:研究递送基因纳米粒表面修饰对体外基因转染的影响.方法:利用末端活化的聚乙二醇(PEG)制备PEG化基因壳聚糖纳米粒;通过两端活化的PEG将糖蛋白配基连接到纳米粒表面,完成肝靶向纳米粒的制备;用透射电镜观察表面修饰对纳米粒粒径大小、粒子形态的影响;使用蛋白质测定试剂盒测算纳米粒表面蛋白连接量;利用体外转染实验考察表面修饰对纳米粒转染活性的影响;用倒置荧光显微镜观察并用流式细胞仪测定转染结果.结果:纳米粒PEG化使转染效率大幅度升高,半乳糖基牛血清白蛋白(Galn-BSA)使体系的转染效率比PEG化纳米粒略有下降,但比不经修饰的纳米粒转染活性高.壳聚糖纳米粒的表面PEG化能提高纳米粒的体外稳定性,从而提高体外转染效率,并适合于进行冷冻干燥.结论:长循环壳聚糖基因递送纳米粒在基因治疗研究中可能会发挥重要作用.     

壳聚糖纳米粒用作基因递送载体的初步研究

目的初步研究基因壳聚糖纳米粒的性质和转染活性。方法用复凝聚法制备纳米粒;用透射电镜观察形态;用纳米粒度分析仪测定粒径、多分散度和zeta电位;用荧光分光光度法测定基因包封率;用凝胶阻滞分析和荧光扫描测定基因在纳米粒中的位置;用体外基因转染实验定性评价纳米粒的转染活性。结果纳米粒形态多呈球形,平均粒径为218.9 nm,多分散度为0.276,zeta电位为+21.2 mV;基因包封率为99.6%;凝胶阻滞分析和荧光扫描表明基因几乎全部被包裹在纳米粒内部,表面吸附很少;体外基因转染实验表明基因壳聚糖纳米粒能够转染人胚胎肾细胞(HEK293)和肝癌细胞(HepG2),基因能够在这两种细胞中表达。结论壳聚糖纳米粒能将基因递送到细胞内并且基因能够表达,因此可以用作基因药物载体。     

葫芦素B-聚乳酸-羟基乙酸共聚物载药纳米粒的构建与药效学评价

目的 以聚乳酸-羟基乙酸共聚物（PLGA）作为纳米制剂载体材料将葫芦素B制备成纳米粒,并考察其对HepG2肝癌细胞的抑制效果。方法 使用乳化溶剂蒸发法制备葫芦素B-PLGA载药纳米粒,以PLGA浓度（X₁）、PVA浓度（X₂）和药物浓度（X₃）作为考察因素,以载药纳米粒的粒径大小（Y₁）和包封率（Y₂）作为评价指标,应用中心复合设计-效应面法优化葫芦素B-PLGA载药纳米粒处方;测定了纳米粒的粒径分布和Zeta电位值,通过透射电镜观察其微观形态,并考察了葫芦素B-PLGA载药纳米粒的体外药物释放特性;比较了葫芦素B与葫芦素B-PLGA载药纳米粒对HepG2肝癌细胞的抑制效果。结果 葫芦素B-PLGA载药纳米粒的最优处方组成为：PLGA浓度为9.0%,PVA浓度为2.0%,药物浓度为4.5%,制备的纳米粒粒径为（145.4±15.8） nm,Zeta电位值为（-7.6±0.8） mV;透射电镜下可观察到纳米粒表面光滑,分布均匀;葫芦素B-PLGA载药纳米粒释药前期出现突释,后期平缓,48 h药物释放达到86%;葫芦素B-PLGA载药纳米粒对HepG2肝癌细胞的抑制作用显著高于葫芦素B。结论 葫芦素B-PLGA载药纳米粒可延缓药物释放,提高对HepG2肝癌细胞的抑制活性,为进一步临床研究奠定实验基础。     

基因壳聚糖纳米粒表面修饰和转染研究

目的：研究递送基因纳米粒表面修饰对体外基因转染的影响。方法：利用末端活化的聚乙二醇(PEG)制备PEG化基因壳聚糖纳米粒;通过两端活化的PEG将糖蛋白配基连接到纳米粒表面,完成肝靶向纳米粒的制备;用透射电镜观察表面修饰对纳米粒粒径大小、粒子形态的影响;使用蛋白质测定试剂盒测算纳米粒表面蛋白连接量;利用体外转染实验考察表面修饰对纳米粒转染活性的影响;用倒置荧光显微镜观察并用流式细胞仪测定转染结果。结果：纳米粒PEG化使转染效率大幅度升高,半乳糖基牛血清白蛋白(Galn—BSA)使体系的转染效率比PEG化纳米粒略有下降,但比不经修饰的纳米粒转染活性高。壳聚糖纳米粒的表面PEG化能提高纳米粒的体外稳定性,从而提高体外转染效率,并适合于进行冷冻干燥。结论：长循环壳聚糖基因递送纳米粒在基因治疗研究中可能会发挥重要作用。     

载ACE-shRNA pGenesil质粒与壳聚糖纳米粒的结合及释放实验

目的制备适当粒径的壳聚糖纳米粒,并连接上质粒,研究壳聚糖纳米粒对质粒DNA的结合能力及在体外的释放。方法采用离子交联法制备壳聚糖纳米粒,通过喷金电镜观察其大小、形态及分布;经琼脂糖凝胶电泳分析纳米载体与质粒DNA的结合能力;在4种不同pH值的磷酸盐缓冲液(PBS)中观察壳聚糖质粒纳米粒的释放情况;通过紫外分光光度计检测其包埋率及释放率。结果喷金电镜证实壳聚糖纳米粒分布均匀,呈近似球形,平均粒径约5nm;琼脂糖凝胶电泳结果显示壳聚糖纳米粒能有效地结合质粒,当纳米粒与质粒的比例为10∶10时包埋率达98.7%;壳聚糖质粒纳米粒的性质较稳定,在pH值<7.5的PBS溶液能够平稳释放100h左右。结论制备出适当粒径且分布均匀的壳聚糖纳米粒,能有效地结合质粒,并且能够持续平稳地释放。     

载基因壳聚糖纳米粒的制备及其相关性质的初步研究

目的制备壳聚糖载基因纳米粒，并对其体外相关性质进行初步研究。方法采用复凝聚法制备载基因纳米粒；用纳米粒度仪测量粒度分布、多分散性和Zeta电位；用透射电镜观察粒子的形态；用荧光分光光度法和比色法测定包封率和载药量，并对主要影响因素进行考察；用凝胶阻滞分析和电性结合分析对载药方式进行初步推测。结果所制备的载基因纳米粒形态规则，大多呈球形，平均粒径约150nm，PDI＜0．2，Zeta电位约20mV；包封率大于90％，载药量约30％；凝胶阻滞和电性结合分析结果表明，pDNA与壳聚糖分子间可通过电性结合作用而完全结合。结论采用复凝聚法可制备粒度分布均匀，形态规则，具有较高包封率和载药量的载基因壳聚糖纳米粒；电性结合作用是载基因壳聚糖纳米粒载药的主要方式。     

载基因壳聚糖纳米粒的制备及其相关性质的研究

目的：制备壳聚糖载基因纳米粒，并对其体外相关性质进行初步研究。方法：采用复凝聚法制备载基因纳米粒；用纳米粒度仪测量粒度分布，分散性和Zeta电位；用透射电镜观察粒子的形态；用紫外分光光度法和比色法测定包封率和载药量，并对主要影响因素进行考察。用凝胶阻滞分析和电性结合分析对载药方式进行初步推测。结果：所制备的载基因纳米粒形态规则，大多呈球形，纳米粒平均粒径为263．2nm，粒径分布较窄，多分散度为0．213，Zeta电位为19．8mV；包封率大于90％，载药量约30％；凝胶阻滞和电性结合分析结果表明，非甲基化胞嘧啶鸟嘌呤的寡核苷酸链（CPG-ODN）与壳聚糖分子间可通过电性结合作用而完全结合。结论：采用复凝聚法可制备粒度分布均匀，形态规则，具有较高包封率和载药量的载基因壳聚糖纳米粒；电性结合作用是载基因壳聚糖纳米粒载药的主要方式。     

Glycyrrhizin surface-modified chitosan nanoparticles for hepatocyte-targeted delivery

The aim of the present work was to investigate the potential utility of chitosan nanoparticles surface modified with glycyrrhizin (CS-NPs-GL) as new hepatocyte-targeted delivery vehicles. For this purpose, chitosan nanoparticles (CS-NPs) were prepared previously by ionic gelation process and glycyrrhizin was oxidized by sodium periodate to be conjugated to the surface of CS-NPs. The CS-NPs-GL obtained were first characterized for their morphology, particle size, zeta potential, association efficiency and in vitro release of adriamycin (ADR), using as a model drug. The nanoparticles were also labeled with rhodamine B isothiocyanate and their interaction with rat hepatocytes was examined by flow cytometry (FCM) and confocal laser microscopy (CLSM). The spherical nanoparticles prepared with oxidized GL/CS ratio of 0.14:1 (w/w) were in the 147.2nm size range, and exhibited a positive electrical charge (+9.3mV), and associated ADR quite efficiently (association efficiency: 91.7%) and showed lower extent of release (28% over 72h) in vitro. FCM and CLSM studies showed that CS-NPs-GL were preferentially accumulated in hepatocytes and the cellular uptake amount were 4.9 times more than that in hepatic nonparenchymal cells, and the uptake process was dependent on incubation time and dose of nanoparticles, which indicated that the internalization of these nanoparticles into hepatocytes was mostly mediated by a ligand-receptor interaction. In conclusion, CS-NPs-GL as a promising hepatocyte-targeted delivery carrier holds promise for further effective studies.     

Norcantharidin-associated galactosylated chitosan nanoparticles for hepatocyte-targeted delivery

In this study a new chitosan (CS) derivative, galactosylated chitosan (GC), was synthesized and used to prepare norcantharidin-associated GC nanoparticles (NCTD-GC NPs) by taking advantage of the ionic cross-linkage between the molecules of the anti-hepatocarcinoma medicine NCTD and of the GC as carrier. NCTD-GC NPs were obtained with average particle size of 118.68 ± 3.37 nm, entrapment efficiency of 57.92 ± 0.40%, and drug-loading amount of 10.38 ± 0.06%. Several important factors influencing the entrapment efficiency, drug-loading amount, and particle size of NCTD-GC NPs were studied. The characteristics of sustained and pH-sensitive release of NCTD from NCTD-GC NPs in vitro were studied. In addition, in vitro cellular uptake and cytotoxicity of nanoparticles to hepatoma cell lines SMMC-7721 and HepG2 were also investigated. In vitro, and compared to CS-based NCTD-CS NPs, NCTD-GC NPs demonstrated satisfactory compatibility with hepatoma cells and strong cytotoxicity against hepatocellular carcinoma cells. In vivo antitumor activity of NCTD-GC NPs was evaluated in mice bearing H22 liver tumors. NCTD-GC NPs displayed tumor inhibition effect in mice, better than either the free NCTD or the NCTD-CS NPs. As a hepatocyte-targeting carrier, GC NPs are potentially promising for clinical applications.From the Clinical EditorIn this paper, a galactosylated chitosan (GC), was synthesized and norcantharidin (NCTD)-associated galactosylated chitosan nanoparticles (NCTDGC NPs) were generated by coupling NCTD - an anti-hepatocarcinoma drug - and GC as carrier. Compared to chitosan nanoparticles, NCTD-GC-NPs demonstrated satisfactory compatibility with hepatoma cells and strong cytotoxicity against the cells.     

Spermine grafted galactosylated chitosan for improved nanoparticle mediated gene delivery

Despite multitude of beneficial features, chitosan has poor water solubility and transfection ability which affect its gene delivery efficacy. The two features are improved when certain chemical modifications are incorporated into the chitosan parent backbone. This strategy is adopted here, by coupling galactose and spermine into the chitosan backbone. The conjugation was determined with FTIR and (1)H NMR and nanoparticle morphology was assessed by TEM and AFM techniques. Particle size, zeta potential, buffering capacity and DNA binding ability gave encouraging result of enhanced solubility and stability. In vitro studies of GCSM in HepG2 cell lines displayed low cytotoxicity and improved transfection. We also identified the preference of receptor mediated internalization for nanoparticles cellular uptake by treating with cellular uptake inhibitors. The results evidently led us to comprehend that galactosylated chitosan-g-spermine could be considered as a promising chitosan derivative for conducting nanoparticle mediated gene delivery.     

Chitosan/cyclodextrin nanoparticles can efficiently transfect the airway epithelium in vitro

The main goal of the present study was to investigate the potential of a new generation of hybrid polysaccharide nanocarriers, composed of chitosan (CS) and anionic cyclodextrins (CDs), for gene delivery to the airway epithelium. More specifically, these nanocarriers were investigated with regard to their ability to enter epithelial cells and promote gene expression in the Calu-3 cell culture model.In the search for the most suitable nanocarrier composition for gene delivery, the effect of CS molecular weight (Mw) on the nanocarriers characteristics and their ability to transfect cells was investigated. Thus, hybrid CS/CD nanoparticles were prepared with two different CS Mw, medium (110 kDa) and low (10 kDa), and loaded with pSEAP (plasmid DNA model that encodes the expression of secreted alkaline phosphatase). The resulting nanoparticles presented an adequate size range (100-200 nm, depending on CS Mw), a positive surface charge (+22 to +35 mV) and very high DNA association efficiency values (>90%). Cellular uptake studies showed that the nanoparticles were effectively internalized by the cells, providing a good indication of their potential as gene carriers. The transfection efficiency of the different formulations, measured by the concentration of secreted gene product (SEAP), indicated that all the nanoparticles were able to elicit a significantly higher response than the naked DNA (control), the transfection efficiency being more important for low MwCS nanoparticles than for those composed of medium MwCS. Overall, this report is the first evidence of the potential of a new generation of safe polysaccharide nanocarriers for gene delivery to the airway epithelium.     

Chitosan-associated SLN: in vitro and ex vivo characterization of cyclosporine A loaded ophthalmic systems

The aim of this study was to develop cyclosporine A (CsA) loaded solid lipid nanoparticles (SLN) associated with chitosan (CS), to improve interaction and internalization in corneal cells. The SLN were prepared using high shear homogenization and ultrasound methods with CS in the aqueous phase. The lipid phase was based on Compritol or Precirol. The SLN were characterized for particle size, polydispersity index, morphology, zeta potential and encapsulation efficiency. The systems were freeze-dried to increase physical stability and trehalose was used as a cryo/lyo-protector to stabilize the SLN. The penetration and permeation properties of the SLN were assessed in?vitro (cell culture) and ex vivo (excised pig cornea). The cell uptake of SLN was studied by means of confocal laser scanning microscopy. CS-associated SLN based on Compritol were biocompatible and enhanced the permeation/penetration of CsA along with a possible mechanism of internalization/uptake of the nanoparticles both in?vitro and ex vivo.