碳纳米管的表面改性及其在NMMO水溶液中的分散稳定性

研究了采用硝酸回流方法纯化的多壁碳纳米管(MWNTs)在不同类型的表面活性剂中的分散稳定性,从中选用十二烷基苯磺酸钠(SDBS)对纯化后的MWNTs进行表面功能化,并利用透射电子显微镜、红外光谱仪和光学显微镜等对MWNTs的纯化和表面功能化效果及其在N-甲基吗啉-N-氧化物(NMMO)水溶液中的分散性能进行了分析,实验结果表明,通过硝酸回流纯化处理,能够使MWNTs表面拥有较多的羧基和羟基.在超声波作用下,SDBS可以对纯化后的MWNTs进行表面功能化,使其在NMMO水溶液中具有较好的分散稳定性.     

左旋多巴在纳米材料修饰界面上的电子传递

利用多壁碳纳米管(MWNTs)和量子点(QDs)作为修饰材料,采用简便的干燥吸附法制备玻碳修饰电极(GCE),构造了纳米材料修饰界面,采用循环伏安法和计时库伦法对左旋多巴的电化学行为进行了探讨.发现该电化学行为是一个两电子两质子的过程.该修饰电极能很好地催化左旋多巴的电化学行为,能够有效地促进它与电极之间的电子传递,有良好的电化学响应.其在修饰电极上的异相电子传递速率常数为0.595 cm·s~(-1),比在裸GCE和MWNTs修饰GCE上有很大提高.这很可能是由于QDs和MWNTs之间存在着某种协同作用,提高了MWNTs对左旋多巴的电化学催化能力所致.这一研究结果为在纳米复合修饰电极上研究生物小分子的电化学催化提供了一种新途径.     

表面活性剂对普鲁士蓝复合修饰电极性能的影响

使用滴涂的方法制备多壁碳纳米管(MWNTs)修饰电极(MWNTs/GCE),并利用循环伏安法在该电极表面沉积普鲁士蓝(PB),从而得到普鲁士蓝-多壁碳纳米管复合修饰电极(PB/MWNTs/GCE),相对于相同条件下在裸玻碳电极表面制备的PB修饰电极,该电极表现出更优良的电化学性质。通过使用不同性质的表面活性剂对MWNTs进行分散,制备了系列MWNTs基PB修饰电极,并研究了表面活性剂对PB复合修饰电极性能的影响。实验结果表明,表面活性剂的加入提高了PB/MWNTs/GCE基修饰电极对过氧化氢的检测范围。     

多羟基超支化聚(胺-酯)修饰多壁碳纳米管

通过原位酯交换聚合反应,在多壁碳纳米管(MWNTs)表面接枝多羟基超支化聚胺-脂取得成功.分步产物的结构用FTIR进行了表征,TGA确定了修饰类型为共价接枝,SEM观察到MWNTs改性前后的形貌变化,并首次采用化学滴定方法确定了接枝在碳纳米管上的超支化聚合物的平均代数.接枝修饰后的MWNTs在水、乙酸乙酯等常见溶剂中的分散能力明显提高.     

介电泳操控不同基团修饰多壁碳纳米管气体传感器对SO_2的气敏性能

利用介电泳法在铬-银-金微电极上制备了本征多壁碳纳米管(MWNTs)气体传感器及不同基团修饰多壁碳纳米管(MWNTs-x,x:NH2,OH,COOH)气体传感器,考察了MWNTs和MWNTs-x在非均匀电场中的介电响应行为,将8 V,2 MHz的电泳参数确定为多壁碳纳米管气体传感器的制备条件;在介电泳力作用下MWNTs和MWNTs-x的颗粒均被捕获到电极尖端,发生了正介电泳(p-DEP).室温下研究了制备的气体传感器对不同浓度二氧化硫(SO2)的气敏性能,研究发现传感器对SO2的响应时间、恢复时间和灵敏度随SO2气体浓度的增加而增大,不同基团修饰MWNTs气体传感器对SO2的灵敏度较本征MWNTs传感器的灵敏度显著提高,氨基修饰MWNTs(MWNTs-NH2)气体传感器的灵敏度最高,为本征MWNTs气体传感器的17–23倍,碳管与SO2间的毛细力、表面张力、氢键、化学键等相互作用为影响传感器气敏性能的因素.     

重组人睫状神经营养因子突变体的制备及PEG修饰

通过大肠杆菌重组表达人睫状神经营养因子突变体(CNTFm),并进行PEG修饰,旨在降低免疫原性.该突变体将天然CNTF的C端15个氨基酸删除,大肠杆菌表达的CNTFm以包含体形式存在,经复性、纯化获得纯度达到95%的目的蛋白.体内生物学活性测定结果显示,给药10 d,小鼠最大体重减少率达31%,产生的最高中和抗体滴度达到1:6 400; 经PEG修饰,CNTF突变体的生物学活性降低了34%,但最高中和抗体滴度降低到1:800.该PEG修饰后的CNTFm制备工艺有望为CNTF的临床应用开辟道路.     

末端连接ω-氨基酸的聚乙二醇修饰剂的制备

提出了一种新型聚乙二醇(PEG)修饰剂的合成方法。首先以两种ω-氨基酸和单甲氧基PEG为主要原料,经连接、纯化和水解等步骤,得到末端以酰胺键连接ω-氨基酸的PEG酸,再将得到的PEG酸用N-羟基琥珀酰亚胺(NHS)进行活化,得到聚乙二醇-β-丙氨酸-N-羟基琥珀酰亚胺酯(PEG-BPA-NHS)和聚乙二醇-γ-氨基丁酸-N-羟基琥珀酰亚胺酯(PEG-GABA-NHS),总收率为60%。这类新的修饰剂经验证具有较长的水解半衰期(分别为7.6 min和16.7 min)和良好的蛋白修饰能力。     

多壁碳纳米管/聚丙烯酸复合材料的制备及表征

采用化学气相沉积法(CVD)制备多壁碳纳米管(MWNTs),并用酸纯化多壁碳纳米管(MWNTs).为了改进碳纳米管在聚合物中的性能,采用化学修饰法制备了多壁碳纳米管/聚丙烯酸(MWNTs/PAA)复合材料,并用扫描电镜(SEM)、透射电镜(TEM)和红外光谱(FT-IR)对其进行了表征.实验结果表明,聚丙烯酸能均匀地包覆在碳纳米管表面,而且多壁碳纳米管/聚丙烯酸复合材料能很好地分散在水和苯丙乳液中.     

可降解瓜尔胶载药微胶囊的聚乙二醇修饰

通过将三聚磷酸纳溶液滴加到阳离子瓜尔胶和聚乙二醇(PEG)混合水溶液中,利用多糖聚电解质的离子凝胶化反应首次制得经PEG修饰的可降解瓜尔胶微胶囊,并用扫描电镜对其表面形态和粒径大小进行了考察;通过对不同浓度牛血清白蛋白和阿司匹林二种模型药物的负载实验,发现修饰后的微胶囊比未经修饰的微胶囊有增大的负载百分率和载药量.     

超氧化物歧化酶经谷胱甘肽和Y型聚乙二醇共修饰后的性质研究

使用谷胱甘肽(GSH)和40ku-Y型聚乙二醇(PEG)作为修饰剂,对超氧化物歧化酶(SOD)进行2次修饰,获得了GSH和PEG共修饰的超氧化物歧化酶(PEG-GSOD).分别测定PEG-GSOD与普通SOD的热稳定性、抗胰酶稳定性、抗变性剂稳定性等,并进行比较研究,结果显示:PEG-GSOD比普通SOD(没有修饰的)在热、抗胰酶、抗变性剂等方面的稳定性均有明显提高;通过新西兰兔的体内实验,将PEG-GSOD和普通SOD分别对新西兰兔静脉注射,普通SOD注射0.5h后,SOD酶活性降低至0,而PEG及GSH联合修饰的PEG-GSOD,注射48h后,血浆SOD活性检测还保留约75%,注射72h后,酶活力保留约40%,测得PEG-GSOD在新西兰兔体内半衰期约为50h.此结果说明,PEG-GSOD,其在体内的半衰期显著延长,稳定更好,该研究为SOD药物的应用奠定了基础.     

Oxidative damages to DNA by indoor PM_(10)s: Their relationships with trace element compositions

Inrecentyears,adversehealtheffectsofinhal ableparticles(PM10)havedrawnmoreattention.Moreover,epidemiologicalstudieshavehighlighteda possiblelinkbetweentheincreasesinPM10concentra tionandtheadultmorbidityandmortality[1,2].How ever,thebiologicalmechanismoftheadverseeffects isstillunclear.Therearemanyhypothesesonthe mechanismscausingpulmonarydamagebyparticulate matters,ofwhichawidelyacceptedhypothesisis thatthebioavailabletransitionmetalsonparticlesur facemayproducefreeradicals,whichplayanimpor…     

DNA damage and repair

The aesthetic appeal of the DNA double helix initially hindered notions of DNA mutation and repair, which would necessarily interfere with its pristine state. But it has since been recognized that DNA is subject to continuous damage and the cell has an arsenal of ways of responding to such injury. Although mutations or deficiencies in repair can have catastrophic consequences, causing a range of human diseases, mutations are nonetheless fundamental to life and evolution.     

Clustered DNA damage induced by protons radiation in plasmid DNA

Clustered DNA damage is considered as a critical type of lesions induced by ionizing radiation, which can be converted into the fatal or strong mutagenic complex double strand breaks (DSBs) during damage processing in the cells. The new data show that high energy protons produce more potentially lethal DSBs than low LET radiation. In this study, plasmid DNA were used to in-vestigate and re-evaluate the biological effects induced by the protons with the LET of ～3.6 keV/μm at the molecular level in vitro, including single strand breaks (SSBs), DSBs, isolated and clustered base damages. The results of complex DNA damage detections indicated that protons at the given LET value induce about 1.6 fold more non-DSB clustered DNA damages than the prompt DSB. The DNA damage yields by protons were greater than that by γ-rays, specifically by 6 fold for the isolated type of DNA damage and 14 fold for the clustered damage. Furthermore, the spectrum of damages was also demonstrated to be depended on the radiation quality, with protons producing more DSBs relative to clusters than do γ-rays.     

水稻基因整合平台系统供体质粒pURKMT的构建

提高水稻产量,改良稻米品质是育种学家广泛研究的课题．随着现代生物技术的发展,水稻已成为植物基因工程的重要研究对象．许多实验室已成功地建立了一系列供外源基因转化水稻的系统．但是这些转化系统主要应用Ｔｉ质粒衍生的载体,通过Ｔ－ＤＮＡ左右两端的序列将目的基...     

The DNA concentration effect on DNA radiation damage induced by <Superscript>7</Superscript>Li ions and γ rays

To evaluate the influence of the DNA concentration in the aqueous solution on DNA radiation damage, the plasmid DNA in the presence or absence of Mannitol （scavenger of free radical OH.） was irradiated by ^7Li ions and γ rays at various DNA concentrations. Gel electrophoresis analysis revealed that the DNA damage of single and double strand breaks induced by irradiation became more severe at lower DNA concentration. In the condition of γ-ray irradiation, most of double strand breaks （DSB） damage was neutralized and less associated with DNA concentration in the presence of mannitol. However, under ^7Li irradiation, DSB damage could not be cleared by mannitol but was gradually aggravated with decreasing DNA concentrations. These findings imply that under low-LET irradiation, most of the DSB damage is generated by free radical OH·diffusion, and thus may be counteracted by scavengers, while at higher-LET irradiation, quite a fraction of DSB induction is caused by direct ionizing energy deposition of heavy ions, which cannot be eliminated. This work also indicates that the proportion between free radical damage and direct ionizing damage is s constant which is independent of DNA concentration when the DNA concentration is under a certain value （50ng/μL）. Our study sheds light on the un- derlying mechanisms in the DNA radiation damage process.     

XPS研究多壁碳纳米管的阳极氧化处理效果

采用阳极氧化法对多壁碳纳米管（MWNTs）进行表面处理以提高其表面极性官能团含量。研究了不同电解参数对MWNTs处理结果的影响，采用X射线光电子能谱对处理前后的MWNTs的表面特征进行了分析。结果表明，经阳极氧化处理后，MWNTs表面氧原子摩尔分数与极性官能团总量均有不同程度增加。通电量和碱性电解质的电导率（物质的量浓度）是阳极氧化处理过程的主要影响因素，MWNTs表面极性官能团总量的增加可以归结为羟基的增加和羰基的减少，另外还探讨了可能的氧化反应机理。     

Efficient expression of human factor Ⅸ cDNA in liver mediated by hydrodynamics-based plasmid administration

Hydrodynamics-based administration via tail vein was used to deliver naked plasmid with human factor IX (hFIX) cDNA in 2.2 mL Ringer‘s solution into mice within 7 s. The peak level of expression of hFIX was 2921 ng/mL in mouse plasma. The hFIX cDNA expression increased with increasing the amount of plasmid DNA injected. The peak level of gene expression declined after repeated injection of plasmid (1459 ng/mL). The hFIX cDNA was detected in various organs, but the highest level of gene expression appeared in liver. Transaminase levels and liver histologicalresults showed that rapid intravenous plasmid injection into mice induced transient focal acute liver damage, which was rapidly repaired within 3--10 d. These results suggested that high-level expression of hFIX cDNA can be achieved by hydrodynamics-based plasmid transfer and this method is nowfurther used for gene therapy and gene function study in our lab.     

新基因hSSB1逆转录病毒载体的构建、鉴定和稳定株的筛选

 hSSB1 (Human Single strand DNA binding protein) 是参与细胞DNA损伤应答的一个重要信号分子。根据GenBank 提供的hSSB1基因序列扩增其cDNA序列,插入到pBABE逆转录病毒载体中, 连接后的质粒转化后经过双酶切,PCR扩增及测序来鉴定pBABE-hSSB1阳性克隆。将阳性表达的pBABE-hSSB1和包装质粒转染到HEK293T细胞中,产生病毒液。将包装好的病毒感染细胞并用嘌呤霉素(puromycin)筛选稳定表达hSSB1的细胞株。重组pBABE-hSSB1质粒经双酶切,PCR扩增鉴定及DNA测序分析等方法证实克隆成功。Western blotting检测发现转染重组质粒pBABE-hSSB1的细胞株中hSSB1蛋白的表达水平高于对照组。该研究成功构建了针对hSSB1基因的逆转录病毒载体(pBABE-hSSB1),并得到了稳定高表达hSSB1的细胞株, 为深入研究其功能奠定了基础。     

MWNTs/TiO2对1,2,3-三氯苯的吸附与光降解协同作用研究

以典型氯苯类有机化合物1,2,3-三氯苯(1,2,3-TCB)为目标去除物,研究复合光催化剂MWNTs/TiO2(多壁碳纳米管负载二氧化钛)对其吸附与光催化降解协同作用.结果表明,在不同温度、pH值、复合光催化剂投加量、紫外光光强等影响因素作用条件下,MWNTs对1,2,3-TCB的吸附去除率与纳米TiO2对1,2,3-TCB的光催化降解去除率的叠加理论计算值曲线均在MWNTs/TiO2对1,2,3-TCB吸附与光催化降解共同作用曲线的下方,充分体现了MWNTs/TiO2对1,2,3-TCB的吸附与光降解初始阶段的协同作用.溶液中温度或pH值降低,有利于复合光催化剂对1,2,3-TCB的去除;复合光催化剂投加量增多或紫外光光强增大将提高复合光催化剂对1,2,3-TCB的去除率.     

碳纳米管表面的氨基化修饰及其聚脲基纳米复合材料的制备和力学性能研究

设计了一种碳纳米管表面氨基化修饰及其聚脲基纳米复合材料的分子设计和制备方法。首先，通过混酸氧化处理得到羟基化碳纳米管；其次，以原位聚合法，通过聚丙烯酸中羧基和碳纳米管表面羟基的酯化反应，将聚丙烯酸接枝到碳纳米管表面；最后，通过接枝聚丙烯酸和端氨基聚醚D-400的酰胺化反应，在碳纳米管表面实现氨基官能化修饰。将氨基修饰的碳纳米管均匀分散在端氨基聚醚固化剂混合物中，进而与端异氰酸根预聚物组分反应得到碳纳米管/聚脲基纳米复合材料。经测试可知，氨基化碳纳米管质量分数为0.7%时，在聚脲基体中分散比较均匀，且聚脲的拉伸强度比原始碳纳米管修饰的聚脲增加了40%。