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。     

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。     

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。     

载碱性成纤维细胞生长因子质粒纳米粒的制备及体外转染活性研究

目的:制备壳聚糖载bFGF基因纳米粒,并对其体外性质及转染成纤维细胞效率进行考察。方法:以复凝集法制备载绿色荧光蛋白(EGFP)与人碱性成纤维细胞生长因子(bFGF)融合蛋白EGFP-bFGF质粒(pEGFP/bFGF)的壳聚糖纳米粒CS-pEGFP/bFGF,透射电镜、纳米粒度电位仪测定纳米粒形态、粒径和表面电位,凝胶阻滞实验分析质粒与壳聚糖结合情况,细胞增殖实验考察载bFGF质粒转染后对细胞增殖的影响,荧光分光光度计及荧光显微镜观测纳米粒转染成纤维细胞后细胞对EGFP的表达情况。结果:壳聚糖纳米粒可将质粒pEGFP/bFGF成功转入成纤维细胞中并能有效降低转染产生的细胞毒性,细胞自分泌的bFGF能促进成纤维细胞的增殖。结论:载bFGF纳米粒具有提高转染效率、降低毒性及促进成纤维细胞增殖的作用。     

载柚皮素壳聚糖纳米粒的制备及其体外细胞评价

目的：制备柚皮素壳聚糖纳米粒,初步探讨其对人肺腺癌细胞A549的细胞毒性和细胞摄取。方法：以壳聚糖和鱼精蛋白作为载体材料,采用离子胶凝法制备柚皮素壳聚糖纳米粒,透射电镜（TEM）观察其形态,马尔文激光粒度仪测定其粒径、分散度（PDI）和Zeta电位,离心法测定其包封率和载药量,采用恒温振荡水浴法对柚皮素壳聚糖纳米粒进行体外释放度研究,最后采用人肺癌细胞系A549细胞进行了细胞毒性、细胞摄取研究。结果：柚皮素壳聚糖纳米粒为球形或类球形粒子,结构完整,大小均一、球形度好,分散均匀,PDI、粒径、Zeta电位和包封率分别为0.268,139 nm、+15.7 mV和83.34%,柚皮素壳聚糖纳米粒体外释放呈缓释,24 h累积释放量达到了80%以上,体外释药过程用Higuchi方程拟合较好。MTT试验显示不同浓度的壳聚糖纳米粒和细胞作用72 h后,细胞活力均大于95%,本文所制备的壳聚糖纳米粒无细胞毒性。细胞摄取试验表明载FITC的壳聚糖纳米粒和A549细胞作用3 h后,可明显看到大量带绿色荧光的纳米粒穿过细胞膜进入细胞。结论：离子凝胶法成功制得粒径较小的柚皮素壳聚糖纳米粒,具有缓释性好,毒性小,壳聚糖纳米粒摄取率较高,可大大提高药物的利用率,具有广泛的应用前景。     

载血管紧张素转换酶短发卡RNA-聚乙二醇-壳聚糖纳米粒制备以及生物学特性

目的制备载血管紧张素转换酶(ACE)短发卡RNA(sh RNA)壳聚糖纳米粒,并且给予聚乙二醇(PEG)表面修饰,分析其相关物理学、生物学特性,以期获得一种缓释的非病毒载体介导系统。方法应用本实验室前期实验中筛选出的能显著下调ACE基因的靶序列,采用菌液用碱裂解法大量抽提和纯化重组质粒,随机酶切测序,并检测质粒浓度与纯度,采用离子交联法制备壳聚糖纳米粒,PEG修饰壳聚糖纳米粒,复凝聚法制备不同p H值、体积比以及PEG化的载ACEsh RNA壳聚糖纳米。喷金电镜下对各种壳聚糖纳米粒悬液扫描并照相,观察纳米粒与形态。应用凝胶阻滞分析验证载ACEsh RNA壳聚糖纳米多聚复合物的形成及电荷性质。结果1壳聚糖纳米粒的粒径随着溶液p H值的升高而增大,当p H值为5.5时的PEG壳聚糖纳米粒平均粒径(125.8±5.6)nm左右,大小均匀,多分散度最小,分布比较集中,zeta电位为正,有利于与带负电荷的质粒结合;PEG化后也对粒径以及zeta电位无明显影响,但是与壳聚糖相同条件相比,分散度均明显减小,可见更适合制备均匀的纳米粒,利于和质粒结合;壳聚糖与质粒体积比(质量比)为1∶1制备的壳聚糖纳米粒平均粒径较小,故通过细胞膜的通透性较好,多分散度较小,分布比较集中,zeta电位也为正值,有利于与带负电荷的质粒结合。2壳聚糖纳米以及PEG化壳聚糖纳米质粒复合物均有效结合质粒,由于中和了质粒所带的负电荷,凝胶电泳时,质粒不出孔,而裸质粒则出孔;p H<7时壳聚糖分子中大部分的氨基带正电荷能与质粒DNA有效地结合,质粒不出孔;在体积比为1∶1、1∶2、1∶3时,壳聚糖纳米粒能有效地结合质粒。结论所制备的载ACE sh RNA-PEG壳聚糖纳米粒大小均匀,粒径分布范围较窄,并且筛选出在p H=5.5时,与质粒体积比为1∶1时,以PEG壳聚糖纳米粒作为载体有良好的结合力,为后期体外转染培养细胞以及体内转染提供了实验基础。     

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.     

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。     

聚乙烯亚胺-聚甲基丙烯酸甲酯阳离子纳米粒介导基因转移的研究

目的研究聚乙烯亚胺-聚甲基丙烯酸甲酯(PEI-PMMA)纳米粒作为基因载体的性能，探讨阳离子纳米粒介导基因转移机制。方法用自由基聚合法制备PEI-PMMA阳离子纳米粒，扫描电镜观察粒子形态，zeta粒度仪测定粒径﹑表面电荷，凝胶电泳阻滞分析载基因能力和激光共焦扫描显微镜观察纳米粒介导的细胞内基因转移情况。结果PEI-PMMA纳米粒呈单分散球形，平均粒径为172 nm，zeta电位为+50.3 mV。当pGL3质粒与纳米粒以N/P为5∶1和20∶1形成复合物后纳米粒平均粒径分别为133和139 nm；zeta电位分别为+21.4和+33.7 mV。pGL3可完全与纳米粒形成复合物。PEI-PMMA纳米粒可携带pGL3质粒进入HeLa细胞，并突破吞噬小泡释放质粒于细胞质，最终质粒聚集于细胞核内进行表达。结论PEI-PMMA纳米粒通过内吞作用介导基因转移入靶细胞，可作为基因转移的非病毒型载体。     

粒细胞-巨噬细胞集落刺激因子壳聚糖缓释纳米粒的制备

目的:研究以生物可降解壳聚糖纳米粒作为粒细胞-巨噬细胞集落刺激因子(GM-CSF)新型缓释系统的可行性。方法:以三聚磷酸钠为交联剂,采用离子交联法制备负载GM-CSF和牛血清白蛋白(BSA)的纳米粒。用透射电镜观测纳米粒径和形态;用紫外分光光度计、荧光分光光度计分别测定BSA和GM-CSF包封率,并考察制剂体外药物释放情况。结果:纳米粒形态多呈球形,平均粒径为201nm,GM-CSF和BSA包封率分别为62.1%、58.5% ,3d时体外累积释放率分别为69%、82%。结论:应用离子交联法可制备负载GM-CSF的壳聚糖缓释纳米粒。     

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。     

Chitosan nanoparticles for plasmid DNA delivery: effect of chitosan molecular structure on formulation and release characteristics

Chitosan can be useful as a nonviral vector for gene delivery. Although there are several reports to form chitosan-pDNA particles, the optimization and effect on transfection remain insufficient. The chitosan-pDNA nanoparticles were formulated using complex coacervation and solvent evaporation techniques. The important parameters for the encapsulation efficiency were investigated, including molecular weight and deacetylation degree of chitosan. We found that encapsulation efficiency of pDNA is directly proportional with deacetylation degree, but there is an inverse proportion with molecular weight of chitosan. DNA-nanoparticles in the size range of 450-820 nm depend on the formulation process. The surface charge of the nanoparticles prepared with complex coacervation method was slightly positive with a zeta potential of +9 to +18 mV; nevertheless, nanoparticles prepared with solvent evaporation method had a zeta potential approximately +30 mV. The pDNA-chitosan nanoparticles prepared by using high deacetylation degree chitosan having 92.7%, 98.0%, and 90.4% encapsulation efficiency protect the encapsulated pDNA from nuclease degradation as shown by electrophoretic mobility analysis. The release of pDNA from the formulation prepared by complex coacervation was completed in 24 hr whereas the formulation prepared by evaporation technique released pDNA in 96 hr, but these release profiles are not statistically significant compared with formulations with similar structure (p > .05). According to the results, we suggest nanoparticles have the potential to be used as a transfer vector in further studies.     

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。     

Chitosan Nanoparticles for Plasmid DNA Delivery: Effect of Chitosan Molecular Structure on Formulation and Release Characteristics

Chitosan can be useful as a nonviral vector for gene delivery. Although there are several reports to form chitosan-pDNA particles, the optimization and effect on transfection remain insufficient. The chitosan-pDNA nanoparticles were formulated using complex coacervation and solvent evaporation techniques. The important parameters for the encapsulation efficiency were investigated, including molecular weight and deacetylation degree of chitosan. We found that encapsulation efficiency of pDNA is directly proportional with deacetylation degree, but there is an inverse proportion with molecular weight of chitosan. DNA-nanoparticles in the size range of 450–820 nm depend on the formulation process. The surface charge of the nanoparticles prepared with complex coacervation method was slightly positive with a zeta potential of +9 to +18 mV; nevertheless, nanoparticles prepared with solvent evaporation method had a zeta potential ～ +30 mV. The pDNA-chitosan nanoparticles prepared by using high deacetylation degree chitosan having 92.7%, 98.0%, and 90.4% encapsulation efficiency protect the encapsulated pDNA from nuclease degradation as shown by electrophoretic mobility analysis. The release of pDNA from the formulation prepared by complex coacervation was completed in 24 hr whereas the formulation prepared by evaporation tecnique released pDNA in 96 hr, but these release profiles are not statistically significant compared with formulations with similar structure p >. 05). According to the results, we suggest nanoparticles have the potential to be used as a transfer vector in further studies.     

In vitro evaluation of chitosan-EDTA conjugate polyplexes as a nanoparticulate gene delivery system

It was the purpose of this study to evaluate the potential of different molecular-weight chitosan-EDTA conjugates as a carrier matrix for nanoparticulate gene delivery systems. Covalent binding of EDTA to more than one chitosan chain provides a cross-linked polymer that is anticipated to produce stabilized particles. pDNA/chitosan-EDTA particles, generated via coazervation, were characterized in size and zeta potential by electrophoretic light scattering and electron microscopy. Stability was investigated at different pH values by enzymatic degradation and subsequent gel retardation assay. Lactate dehydrogenase assay was performed to determine toxicity. Furthermore, transfection efficiency into Caco-2 cells was assessed using a beta-galactosidase reporter gene. Chitosan-EDTA produced from low-viscous chitosan with 68% amino groups being modified by the covalent attachment of EDTA showed the highest complexing efficacy resulting in nanoparticles of 43 nm mean size and exhibiting a zeta potential of +6.3 mV. These particles were more stable at pH 8 than chitosan control particles. The cytotoxicity of chitosan-EDTA particles was below 1% over a time period of 4 hours. These new nanoplexes showed 35% improved in vitro transfection efficiency compared with unmodified chitosan nanoparticles. According to these results, the chitosan-EDTA conjugate may be a promising polymer for gene transfer.     

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.     

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.     

尿刊酸偶联壳聚糖基因载体的合成和表征

本文将活化的尿刊酸(urocanic acid，UA)与壳聚糖(chitosan，CTS)上的氨基反应合成一种新型非病毒基因载体——尿刊酸偶联壳聚糖(urocanic acid-coupled chitosan，UAC)，通过红外(FT-IR)、核磁共振(¹H NMR)和元素分析对UAC结构进行确证。用正交实验对取代度的影响因素进行考察，结果表明，随着UA投料量的增加和活化时间的延长，UAC的取代度也随之增大；通过琼脂凝胶电泳阻滞实验分析UAC/质粒DNA(plasmid DNA，pDNA)的复合能力及对DNase I酶抗降解能力，结果证明UAC与pDNA有较好的复合能力和抵制DNase I酶降解能力；通过测定UAC/pDNA复合物粒径和对zeta电位的分析，结果证明复合物具有良好的稳定性和易于进入细胞的性质；体外细胞转染是通过荧光显微镜观察UAC介导pDNA在体外培养HepG2细胞中的表达，结果显示，UAC能介导pDNA转染HepG2细胞并在细胞中表达绿色荧光蛋白，其转染效果较CTS明显增强。因而UAC是一种制备工艺简单，具有应用前景的非病毒基因载体。