Degradable poly(ester amine) based on poly(ethylene glycol) dimethacrylate and polyethylenimine as a gene carrier

Degradable poly(ester amine) (PEA) based on poly(ethylene glycol) dimethacrylate (PMEG) and polyethylenimine (PEI) were synthesized by Michael addition reaction. The ratios of PEI to PMEG in PEAs were 0.99, 1.02, and 1.07 with corresponding number‐average molecular weight of 1.3 × 10⁴, 1.2 × 10⁴, and 0.9 × 10⁴, respectively. Degradation rate of PEA at pH 7.4 was higher than that at pH 5.6. Good plasmid condensation and protection ability was shown when N/P molar ratio of PEA to DNA was above 15 (N: nitrogen element in PEA, P: phosphate in DNA). PEA/DNA complexes had positive zeta potential, narrow size distribution, good dispersity, and spheric shape with size below 250 nm when N/P ratio was above 30, suggestion of their endocytosis potential. Compared with PEI 25 KDa, the PEAs showed essential nontoxic to HeLa, HepG2 and 293T cells. With an increase in the molecular weight of PMEG, the transfection efficiency of PEAs in HeLa, HepG2 and 293T showed a tendency to decrease as well as the percent decrease of gene transfection efficiency with serum. The mechanism of PEA‐mediated gene transfection was attributed to “proton sponge effect” of PEI in the PEA. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Environmentally Benign Polyelectrolyte Complex That Renders Wood Flame Retardant and Mechanically Strengthened

Home structure fires are responsible for a majority of fire deaths and injuries. Wood is a key component of home construction due to its excellent mechanical properties and renewability, but it is inherently flammable. This study demonstrates the ability of a waterborne polyelectrolyte complex (PEC) to significantly increase wood's time to ignition, while decreasing peak heat release rate and total heat release. The PEC treatment, comprised of polyethylenimine and sodium hexametaphosphate, preserves the visual aesthetic of the wood and adds little additional weight (ca. 6%), while concurrently increasing flexural modulus and flexural strength. Scanning electron microscope images after torch testing provide evidence of a microintumescent flame retardant mechanism. This unique water‐based coating provides an environmentally benign means to render wood construction much safer.     

Development of Covalent Chitosan-Polyethylenimine Derivatives as Gene Delivery Vehicle: Synthesis,Characterization, and Evaluation

There is an increasing interest in cationic polymers as important constituents of non-viral gene delivery vectors. In the present study, we developed a versatile synthetic route for the production of covalent polymeric conjugates consisting of water-soluble depolymerized chitosan (dCS; M_W 6–9 kDa) and low molecular weight polyethylenimine (PEI; 2.5 kDa linear, 1.8 kDa branched). dCS-PEI derivatives were evaluated based on their physicochemical properties, including purity, covalent bonding, solubility in aqueous media, ability for DNA condensation, and colloidal stability of the resulting polyplexes. They were complexed with non-integrating DNA vectors coding for reporter genes by simple admixing and assessed in vitro using liver-derived HuH-7 cells for their transfection efficiency and cytotoxicity. Using a rational screening cascade, a lead compound was selected (dCS-Suc-LPEI-14) displaying the best balance of biocompatibility, cytotoxicity, and transfection efficiency. Scale-up and in vivo evaluation in wild-type mice allowed for a direct comparison with a commercially available non-viral delivery vector (in vivo-jetPEI). Hepatic expression of the reporter gene luciferase resulted in liver-specific bioluminescence, upon intrabiliary infusion of the chitosan-based polyplexes, which exceeded the signal of the in vivo jetPEI reference formulation by a factor of 10. We conclude that the novel chitosan-derivative dCS-Suc-LPEI-14 shows promise and potential as an efficient polymeric conjugate for non-viral in vivo gene therapy.     

硅疏水改性聚胺阻垢剂的制备及其性能

用γ-缩水甘油醚氧丙基三甲氧基硅烷(KH560)、1-氯辛烷对低相对分子质量聚乙烯亚胺(PEI)进行疏水接枝改性,得到了含硅疏水改性聚胺阻垢剂。通过FTIR、TG、粒径分析、Zeta电位测试等分析改性后聚胺阻垢剂的结构与性能。结果表明,改性后产物热稳定性提高、黏度增大、表面张力降低、溶液粒径增大。将改性聚胺阻垢剂用于分散铝硅酸钠颗粒,对处理前后的颗粒进行红外光谱表征,并通过对悬浮分散液进行稳定性、颗粒沉降等测试,评价聚胺阻垢剂的阻垢分散性能并初步讨论其分散机理。当m(PEI, M_w=10000)∶m(KH560)∶m(1-氯辛烷)=10∶2∶0.5,反应时间6 h,反应温度75℃时,合成的阻垢剂分散性能最佳。当结疤的质量浓度为30 g/L时,悬浮液颗粒沉降速度达到最低值0.047 cm/d,沉降速率减小程度达到94.8%,分散性显著提高。经过改性后的PEI在氧化铝工业生产中具有高效的阻垢作用,可通过在工厂进行条件优化,进一步替代传统的强酸型阻垢剂,减小管道腐蚀程度,降低能耗。     

Modification of electrospun poly(L-lactic acid)/polyethylenimine nanofibrous scaffolds for biomedical application

In this study, modification of poly(L-lactic acid) (PLLA) electrospun nanofibrous scaffolds blending with polyethylenimine (PEI) in different blend ratios was performed. The sample with 85:15 blend ratio revealed most promising results, and was selected for further modification with gelatin. It was found that the presence of PEI could enhanced porosity, mechanical properties, surface/bulk hydrophilicity and also gelatin grafting density about five times with positive effect on cell behavior. The results indicated that the limitations of PLLA electrospun nanofibers for potential application as a functional tissue engineering scaffold (i.e., poor cell adhesion and necrosis of host tissues as a result of providing acidic environment while degradation) could be overcome through blending with PEI and grafting with gelatin.     

Application of magnetic nanoparticles to gene delivery

Nanoparticle technology is being incorporated into many areas of molecular science and biomedicine. Because nanoparticles are small enough to enter almost all areas of the body, including the circulatory system and cells, they have been and continue to be exploited for basic biomedical research as well as clinical diagnostic and therapeutic applications. For example, nanoparticles hold great promise for enabling gene therapy to reach its full potential by facilitating targeted delivery of DNA into tissues and cells. Substantial progress has been made in binding DNA to nanoparticles and controlling the behavior of these complexes. In this article, we review research on binding DNAs to nanoparticles as well as our latest study on non-viral gene delivery using polyethylenimine-coated magnetic nanoparticles.     

商业硅胶负载PEI对CO_2的吸附捕集研究

采用浸渍法制备了商业硅胶负载聚乙烯亚胺(PEI)的CO2吸附剂,研究了该类吸附剂对CO2的吸附捕集性能,同时考察了尿素焙烧法对硅胶孔结构的影响。结果表明:尿素焙烧法可以有效调变商业硅胶的孔结构和比表面积;由硅胶为载体负载PEI后制备的吸附剂具有良好的CO2吸附性能,当PEI负载质量分数为30%时,CO2吸附量最大值可达93.4mg/g;并且在8次吸附-脱附循环测试中CO2吸附量无明显变化,表明该类吸附剂具有良好的CO2吸附再生稳定性能。     

Effective and selective adsorption of uranyl ions by porous polyethylenimine-functionalized carboxylated chitosan/oxidized activated charcoal composite

Composite materials have elicited much interest because of their superior performance in the removal of toxic and radioactive uranyl ions from aqueous solutions.With polyethyleneimine as a functional group,carboxylated chitosan as a matrix,and oxidizing activated carbon as a nanofiller,this study synthesized a novel environment-friendly polyethylenimine-functionalized carboxylated chitosan/oxidized activated charcoal(PCO)biocomposite with a unique three-dimensional porous structure.PCO was synthesized through an easy chemical cross-linking method.Detailed characterization certified the formation of the unique three-dimensional porous structure.The obtained PCO was used to remove uranyl ions from an aqueous solution,demonstrating the maximum adsorption capacity of 450 mg·g^?1.The adsorption capacity of PCO decreased by less than 7.51%after five adsorption-desorption cycles.PCO exhibited good adsorption selectivity(K_d=3.45×10⁴ mL·g^?1)for uranyl ions.The adsorption mechanism of PCO was also discussed.The material showed good potential for application in the treatment of wastewater containing uranyl ions.     

尾静脉注射方法考察Stearic-PEI/SPIO 纳米基因载体的基因转染性能及磁共振可视化效果研究

实验应用硬脂酸-聚乙烯亚胺包裹超顺磁氧化铁(Superparamagnetic Iron Oxide,SPIO)装载目的基因构建可视化 纳米复合物,进行 BABL/c 雌性小鼠体内磁共振成像实验、组织学检测,探讨其是否能够有效地介导体内基因表达以及 产生磁共振成像(Magnetic Resonance Imaging,MRI)效果。MRI 实验结果显示,对小鼠尾静脉注射复合物 0.5 小时后进 行磁共振扫描,与注射生理盐水的对照组相比实验组 T2 加权信号明显降低,信号强度仅为对照组的 35%;48 小时后, 实验组 T2 加权信号强度略有回升,但与对照组信号强度相比仍存在显著差异。组织学结果显示可视化基因纳米复合物 能够穿过血管内皮细胞进入肝脏组织,并释放 DNA 在细胞内成功表达,但基因表达效果较差。综合 MRI 成像及组织检 查实验结果可知,该纳米颗粒具有优良的 MRI 成像性能,但通过尾静脉注射方法基因转染效率较低。     

Composite nickel hydroxide – polyelectrolyte films prepared by cathodic electrosynthesis

Composite films consisting of nickel hydroxide and cationic polyelectrolytes, such as polyethylenimine (PEI) and poly(diallyldimethylammonium chloride) (PDDA) were obtained via cathodic electrodeposition. Films up to 3 m thick were obtained on Pt, graphite and carbon felt substrates. By varying the concentration of the polyelectrolytes in solutions and deposition time, the amount of the deposited material and its composition can be varied. The deposits were studied by thermogravimetric analysis, X-ray diffraction analysis and scanning electron microscopy. The mechanisms of electrochemical intercalation of the cationic polyelectrolytes into nickel hydroxide deposits are discussed.