壳聚糖纳米粒作为基因载体的研究:影响转染效率的因素

目的:以增强型绿色荧光蛋白质粒(pEGFP)为报告基因,探讨影响壳聚糖(CS)介导的基因转染率的因素.方法:复凝聚法制备pEGFP/CS纳米粒,选用HEK293细胞,考察CS相对分子质量、CS中的氨基与pEGFP中的磷酸基的比值(N/P比)、纳米粒粒径、介质pH值和血清对转染率的影响.结果:相对分子质量5×103的CS获得较高转染率;转染率随N/P比增加而提高;介质pH≤6.8有利于转染;在230～1 290nm范围,粒径对转染效率无影响;CS介导的转染不受血清影响.结论:CS相对分子质量、N/P比和介质pH值是影响转染率的因素,低相对分子质量水溶性CS有利于提高转染.     

生物素化壳聚糖纳米粒的制备及其相关性质

制备了生物素化的壳聚糖纳米粒(biotinylated chitosan nanoparticles，Bio-CS-NP)并测定其相关性质，以此作为抗癌药物的载体。制备过程为：先用磺酸琥珀酰亚胺生物素与壳聚糖反应生成生物素化的壳聚糖(biotinylated chitosan，Bio-CS)，再采用氯化钠沉淀法制备Bio-CS-NP。采用试剂盒测定Bio-CS-NP表面配体连接密度，用透射电镜和激光粒度分析仪分别检测纳米粒的形态和粒径，并比较了人肝癌HepG2细胞对Bio-CS-NP和未经生物素修饰的壳聚糖纳米粒(chitosan nanoparticles，CS-NP)的摄取情况。结果显示，Bio-CS-NP表面配体连接密度为2.2 biotin CS；纳米粒形态为圆球形，表面光滑，平均粒径为296.8 nm，多分散指数为0.155；HepG2细胞对Bio-CS-NP的摄取能力显著高于CS-NP(P<0.05)。以上研究结果表明Bio-CS-NP有望成为一种新型的药物载体，用于抗癌药物对癌细胞的主动靶向。生物素的检测方法简便、可行。     

鸟苷二磷酸杂化磷酸钙基因传递系统的制备与细胞学评价

目的采用共沉淀法制备磷酸钙基因给药系统(CaP/pDNA),考察工艺因素和处方因素对CaP/pDNA制备的影响。在此基础上,加入鸟苷二磷酸(GDP)和核定位信号(NLS)制备GDP杂化的磷酸钙基因传递系统Ca(P-GDP)/pDNA/NLS,考察GDP的加入对该系统制剂学性质以及对基因的体外转染的影响。方法通过共沉淀法,以无水CaCl_2为钙源,Na_2HPO_4·12 H_2O为磷源制备CaP/pDNA纳米粒,考察Na_2HPO_4浓度,搅拌速度和搅拌时间对其粒径和包封率的影响,筛选最佳工艺条件和处方组成。以Na_2HPO_4·12 H_2O和GDP为共同磷源,制备Ca(P-GDP)/pDNA/NLS纳米粒。通过体外细胞毒实验和细胞转染实验对制剂加以优化,最终获得具有最佳制剂学性质和体外转染效果的GDP杂化的新型磷酸钙基因传递系统。结果 CaP/pDNA优化处方为Na_2HPO_4浓度为4 mmol·L~(-1),搅拌速度为200 r·min~(-1),反应时间为15 min。CaP/pDNA纳米粒的粒径为160.7 nm,包封率为81.2%;制备的Ca(P-GDP)/pDNA/NLS纳米粒在GDP浓度为20 mmol·L~(-1)时转染效果最好,其粒径为182.9 nm,包封率为84.6%。与参比制剂相比,Ca(P-GDP)/pDNA/NLS纳米粒具有更高的体外转染效率。结论 GDP可以促进含有NLS的磷酸钙基因传递系统的基因的表达效率。     

用离子交联-匀化工艺制备乙肝疫苗壳聚糖纳米粒

目的：研究制备乙肝疫苗壳聚糖（chitosan，CS）纳米粒的适宜条件和影响因素。方法：以CS溶液和三聚磷酸钠溶液，采用离子交联-高压匀化工艺制备乙肝疫苗壳聚糖纳米粒，考察CS的浓度、CS与二聚磷酸钠的质量比及高压匀化对壳聚糖纳米粒粒径和多分散系数的影响，测定了载药纳米粒的包封率和载药量。结果：当CS与三聚磷酸钠的浓度都为2mg/mL，质量比为3：1～6：1，通过离子交联-高压匀化工艺可以得到稳定的纳米粒。纳米粒外观圆整，粒径分布均匀，包封率达到90％以上。结论：用离子交联－高压匀化工艺制备CS纳米粒不需要使用有机溶剂，包封率较高，可以满足给药系统应用要求。     

负载pVAX1-wapA的壳聚糖及季铵化壳聚糖纳米粒的制备研究

目的 制备负载抗龋DNA疫苗pVAX1-wapA质粒的壳聚糖和季铵化壳聚糖纳米粒,优化其制备工艺,测定其细胞转染效率。 方法 以包封率和粒径为主要指标,单因素法考察载体浓度、pH值、N/P、TPP浓度等因素的影响,Realtime-PCR检测细胞对质粒编码蛋白的转录表达水平以评价载质粒纳米粒的促转染作用。 结果 制得的载DNA疫苗纳米粒粒径均一,形态圆整。壳聚糖(CS)纳米粒粒径为(219.2±18.2) nm,Zeta电位为(24.7±3.5) mV,包封率为91.24%。季铵化壳聚糖(CSTM)纳米粒粒径为(222.5±15.6) nm,Zeta电位为(19.6±1.2) mV,包封率为87.66%。纳米粒可以促进pVAX1-wapA进入细胞,并成功被转录。 结论 制备的包载pVAX1-wapA的季铵化壳聚糖纳米粒可用于重组基因疫苗的运送。     

小分子靶向肽修饰壳聚糖作为基因载体的研究

目的:将小分子靶向肽RGD(Arg-Gly-Asp)偶联到壳聚糖(CS)上,并包载质粒DNA(pDNA),制成一种具有靶向性的壳聚糖载基因纳米粒。方法:将RGD肽上的羧基和CS上的氨基通过酰化反应发生偶联,运用红外(FT-IR)和元素分析对RGD偶联壳聚糖(CS-RGD)的化学结构进行确证;采用复凝聚法制备CS-RGD/pDNA纳米粒(CS-RGD/pDNA);应用凝胶阻滞实验和DNA酶(DNase I)降解实验考察CS-RGD对pDNA的复合和保护能力;通过激光粒度仪和原子力显微镜对纳米粒的粒径分布和形态进行考察。结果:CS和RGD肽通过酰胺键偶联;CS-RGD/pDNA在N/P≥2时完全复合,在N/P≥4时具有抗DNase I酶降解能力,N/P=2～30的CS-RGD/pDNA复合物粒径在90～260 nm之间,Zeta电位在4～39 mV之间,原子力显微镜结果证明复合物为类球形且分布良好。具有良好的稳定性和易于进入细胞的性质。结论:CS-RGD是一种制备工艺简单,具有应用前景的非病毒基因载体。     

离子凝胶法制备壳聚糖纳米粒的影响因素研究

目的探讨离子凝胶法制备壳聚糖纳米粒(CS-NPs)的影响因素。方法用碱降解法制备高脱乙酰度的壳聚糖(CS),并以之为材料,采用离子凝胶法制备CS-NPs,以微粒的平均粒径、分散度和Zeta电位为指标,考察CS及三聚磷酸钠(TPP)的质量浓度、CS/TPP质量比、CS溶液p H值和CS溶液温度对制备CS-NPs的影响。并用透射电子显微镜观察纳米粒的形态。结果CS-NPs的平均粒径随CS、TPP质量浓度及CS/TPP质量比的增大而增大,CS/TPP质量比的增加、CS溶液p H值的降低可引起CS-NPs的Zeta电位增高,CS溶液p H值和温度对CS-NPs的分散度影响较大;制备的壳聚糖纳米粒形态较为规则,类似球形。结论CS及TPP的质量浓度、质量比、CS溶液p H值是制备壳聚糖纳米粒并影响其特征的主要因素。     

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。     

中心组合设计法优化载基因壳聚糖纳米粒的最佳转染制备区域

目的：采用中心组合设计法优化载基因壳聚糖纳米粒的最佳转染制备区域。方法采用复凝聚法制备载质粒基因的壳聚糖纳米粒,选择壳聚糖浓度和质粒基因浓度作为实验考察因素,应用两因素五水平中心组合设计优化最佳转染制备区域,优化指标选择平均粒径和基因转染率。通过透射电镜观察纳米粒的形态;通过动态光散射和电泳光散射技术分别测量纳米粒的粒径和Zeta电位;通过凝胶电泳分析考察质粒在纳米粒制备过程中的稳定性;通过倒置荧光显微镜观察质粒基因在细胞内的表达;通过流式细胞技术测定纳米粒的转染效率。结果成功优化了载基因壳聚糖纳米粒的最佳转染制备区域。优选条件下制备的纳米粒大多呈球形,纳米粒平均粒径为217．6 nm,粒径多分散系数为0．241,表明粒径分布较窄。纳米粒zeta电位为＋22．4 mV,表明纳米粒表面带有正电荷,可以增加纳米粒混悬液的稳定性。凝胶电泳分析结果表明质粒基因在纳米粒制备过程中没有遭到破坏。纳米粒的细胞转染效率比较高,能够高效地将绿色荧光蛋白质粒基因递送到细胞内,并且基因表达产生绿色荧光蛋白。结论本研究建立的数学模型具有良好的预测性。在优化的制备区域内制备的载基因壳聚糖纳米粒的转染性能比较理想。     

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。     

Lipoplexes versus nanoparticles: pDNA/siRNA delivery

Abstract

Small interfering RNA (siRNA) has been widely used as potential therapeutic for treatment of various genetic disorders. However, rapid degradation, poor cellular uptake and limited stability in blood limit the effectiveness of the systemic delivery of siRNA. Therefore, an efficient delivery system is required to enhance its transfection and duration of therapeutics. In the present study, plasmid DNA (pEGFPN3) expressing green fluorescent protein (GFP) was used as a reporter gene. Chitosan nanoparticles/polyplexes and cationic liposomes/lipoplexes were developed and compared for their transfectivity and therapeutic activity in mammalian cell line (HEK 293). The nanoparticulates were first characterized by assessing the surface charge (zeta potential), size (dynamic light scattering) and morphology (transmission electron microscope) followed by evaluation for their DNA retardation ability, transfection efficiency and cytotoxicity on HEK 293 cell line. The chitosan nanoparticles/plasmid DNA (pDNA) complex and liposomes/pDNA complex were co-transfected with GFP-specific siRNA into HEK 293 cells and it was found that both are efficient delivery vehicles for siRNA transfection, resulting in ～57% and ～70% suppression of the targeted gene (GFP), respectively, as compared with the mock control (cells transfected with nanocarrier/pDNA complexes alone). This strong inhibition of GFP expression indicated that cationic liposomes are better than chitosan nanoparticles and can be used as an effective carrier of siRNA in mammalian cells.     

Development and characterization of a new plasmid delivery system based on chitosan-sodium deoxycholate nanoparticles

Chitosan is one of the most promising polymers for drug delivery through the mucosal routes because of its polycationic, biocompatible, and biodegradable nature, and particularly due to its mucoadhesive and permeation-enhancing properties. Bile salts are known to interact with lipid membranes, increasing their permeability. The addition of bile salts to chitosan matrices may improve the delivery characteristics of the system, making it suitable for mucosal administration of bioactive substances. In the present study we have developed chitosan nanoparticles using sodium deoxycholate as a counter ion and evaluated their potential as gene delivery carriers. Chitosan-sodium deoxycholate nanoparticles (CS/DS) obtained via a mild ionic gelation procedure using different weight ratios were used to encapsulate plasmid DNA (pDNA) expressing a "humanized" secreted Gaussia Luciferase as reporter gene (pGLuc, 5.7 kDa). Mean particle size, polydispersity index and zeta potential were evaluated in order to select the best formulation for further in vitro studies. The nanoparticles presented an average size of 153-403 nm and a positive zeta potential ranging from +33.0 to +56.9 mV, for nanoparticles produced with CS/DS ratios from 1:4 to 1:0.6 (w:w), respectively. The pDNA was efficiently encapsulated and AFM studies showed that pDNA-loaded nanoparticles presented a more irregular surface due to the interaction between cationic chitosan and negatively charged pDNA which results in a more compact structure when compared to empty nanoparticles. Transfection efficiency of CS/DS-pDNA nanoparticles into moderately (AGS) and well differentiated (N87) gastric adenocarcinoma cell lines was determined by measuring the expression of luciferase, while cell viability was assessed using the MTT reduction. The CS/DS nanoparticles containing encapsulated pDNA were able to transfect both AGS and N87 cell lines, being more effective with AGS cells, the less differentiated cell line. The highest enzymatic activity was achieved with 20% pDNA encapsulated and after 24 h of transfection time. Low cytotoxicity was observed for the CS/DS nanoparticles either with or without pDNA, suggesting this could be a new potential vehicle for mucosal delivery of pDNA.     

The role of protamine amount in the transfection performance of cationic SLN designed as a gene nanocarrier

Cationic solid lipid nanoparticles (SLN) have been recently proposed as non-viral vectors in systemic gene therapy. The aim of this study was to evaluate the effect of the protamine amount used as the transfection promoter in SLN-mediated gene delivery. Three protamine-SLN samples (Pro25, Pro100, and Pro200) prepared by adding increasing amounts of protamine were characterized for their size, zeta potential, and protamine loading level. The samples were evaluated for pDNA complexation ability by gel-electrophoresis analysis and for cytotoxicity and transfection efficiency by using different cell lines (COS-I, HepG2, and Na1300). The size of SLN was ~230?nm and only Pro200 showed few particle aggregates. Unlike the Pro25 sample with the lowest protamine loading level, the others SLN samples (Pro100 and Pro200) exhibited a good ability in complexing pDNA. A cell-line dependent cytotoxicity lower than that of the positive control PEI (polyethilenimmine) was observed for all the SLN. Among these, only Pro100, having an intermediate amount of protamine, appeared able to promote pDNA cell transfer, especially in a neuronal cell line (Na1300). In conclusion, the amount of protamine as the transfection promoter in SLN affects not only the gene delivery ability of SLN but also their capacity to transfer genes efficiently to specific cell types.     

Arginine-chitosan/DNA self-assemble nanoparticles for gene delivery: In vitro characteristics and transfection efficiency

Chitosan (Cs) is a natural cationic polysaccharide that has shown potential as non-viral vector for gene delivery because of its biocompatibility and low toxicity. However, chitosan used for gene delivery is limited due to its poor water solubility and low transfection efficiency. The purpose of this work was to prepare Arginine-chitosan (Arg-Cs)/DNA self-assemble nanoparticles (ACSNs), and determine their in vitro characteristics and transfection efficiency against HEK 293 and COS-7 cells. Our experimental results showed that the particle size and zeta potential of ACSNs prepared with different N/P ratios were 200-400nm and 0.23-12.25mV, respectively. The in vitro transfection efficiency of ACSNs showed dependence on pH of transfection medium, and the highest expression efficiency was obtained at pH 7.2. The transfection efficiency increased with the ratio of chitosan-amine/DNA phosphate (N/P ratio) from 1 to 5, and reached the highest level with the N/P ratio 5. Effect of plasmid dosage on the transfection efficiency showed the highest transfection efficiency was obtained at 4microg/well for HEK 293 cells and 6microg/well for COS-7 cells. The transfection efficiency of ACSNs was much higher than that of Cs/DNA self-assemble nanoparticles (CSNs). The average cell viability of ACSNs was over 90%. These results suggested that ACSNs could be a safe and effective non-viral vector for gene delivery.     

In vitro characterization and transfection of IL-2 gene complexes

BACKGROUND: Interleukin-2 used in the treatment of malignant tumors has an anti-tumor efficacy. In this study, we have studied in vitro characterization and transfection efficiency of a plasmid encoding hIL-2, pCXWN-hIL-2, complexed to chitosan, polyethylenimine or DOTAP with varying ratios. METHODS: Plasmid DNA was amplified in Escherichia coli DH5alpha and isolated by alkali lysis method. The pDNA/chitosan, pDNA/PEI or pDNA/DOTAP complexes were analyzed by agarose gel electrophoresis for complex formation and by ESEM image analysis system for the morphology and DNA/medium relationship of complexes. DNase stability, the particle size and zeta potential values of complexes were determined. Transfection efficiencies of resulting complexes in two different cell lines were assayed by ELISA method. RESULTS: Conclusively, a transfection activity was observed in both cell lines (HeLa and Swiss3T3) with the order of pDNA/DOTAP>pDNA/PEI>pDNA/chitosan complexes. We have observed that the transfection efficiency was higher in HeLa cell line compared to Swiss3T3 cell line. CONCLUSION: The physicochemical studies like stability, particle size and zeta potential, showed a relationship between the properties of a complex and its transfection efficiency.     

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.     

Preparation, characterization, cytotoxicity and transfection efficiency of poly(DL-lactide-co-glycolide) and poly(DL-lactic acid) cationic nanoparticles for controlled delivery of plasmid DNA

The objective of this study was to investigate the effect of formulation parameters (i.e. polymer molecular weight and homogenization speed) on various physicochemical and biological properties of cationic nanoparticles. Cationic nanoparticles were prepared using different molecular weights of poly(DL-lactide-co-glycolide) (PLGA) and poly(DL-lactic acid) (PLA) by double emulsion solvent evaporation at two different homogenization speeds, and were characterized in terms of size, surface charge, morphology, loading efficiency, plasmid release, plasmid integrity, cytotoxicity, and transfection efficiency. Cationic surfactant, cetyltrimethylammonium bromide (CTAB), was used to provide positive charge on the surface of nanoparticles. Reporter plasmid gWIZ Beta-gal was loaded on the surface of nanoparticles by incubation. Use of higher homogenization speed and lower molecular weight polymer led to a decrease in mean particle size, increase in zeta potential, increase in plasmid loading efficiency, and a decrease in burst release. The nanoparticles displayed good morphology as evident from scanning electron micrographs. In vitro cytotoxicity study by MTT assay showed a low toxicity. Structural integrity of the pDNA released from nanoparticles was maintained. Transfecting human embryonic kidney (HEK293) cells with nanoparticles prepared from low molecular weight PLGA and PLA resulted in an increased expression of beta-galactosidase as compared to those prepared from high molecular weight polymer. Our results demonstrate that the PLGA and PLA cationic nanoparticles can be used to achieve prolonged release of pDNA, and the plasmid release rate and transfection efficiency are dependent on the formulation variables.