氮氧自由基定点修饰牛血红蛋白的制备和抗自氧化性能

以4-(N-马来酰亚胺基)-2,2,6,6-四甲基哌啶-1-氮氧自由基(Mal-Tempol)和牛血红蛋白(Hb)为原料,制备了氮氧自由基定点修饰在巯基上的血红蛋白(Mal-Tempol-Hb)。利用分光光度法测定了氮氧自由基的修饰度,通过紫外光谱考察了有无叠氮化钠(NaN_3)介导下,Hb和Mal-Tempol-Hb中高铁血红蛋白(Met Hb)含量随时间变化的过程。结果表明,无NaN_3介导下,180 min时,Mal-Tempol-Hb中Met Hb的摩尔分数由修饰前的44%下降为修饰后的28%;在NaN_3介导下,180 min时,Mal-Tempol-Hb中Met Hb的摩尔分数从修饰前的50%下降为修饰后的32%。氮氧自由基的修饰有效地降低了血红蛋白的自氧化速率。     

阿魏酸修饰的血红蛋白自氧化的研究(加急)

为研究FA-Hb的自氧化,以阿魏酸酯（FA-NBA）与血红蛋白（Hb）为原料,制备了阿魏酸血红蛋白（FA-Hb）。通过紫外光谱扫描、血氧分析仪等检测手段,分析了修饰前后血红蛋白的特征吸收峰的变化情况和氧饱和曲线的差别;研究了有无叠氮钠、黄嘌呤-黄嘌呤氧化酶介导下,血红蛋白和阿魏酸修饰的血红蛋白的自氧化速率的改变。实验结果表明,阿魏酸修饰血红蛋白,保持了血红蛋白的功能结构,仍具备血红蛋白的载氧活性,有效降低了自氧化速率。     

阿魏酸修饰的血红蛋白自氧化的研究

为研究FA-Hb的自氧化,以阿魏酸酯(FA-NBA)与血红蛋白(Hb)为原料,制备了阿魏酸血红蛋白(FA-Hb)。通过紫外光谱扫描、血氧分析仪分析了修饰前后血红蛋白的特征吸收峰的变化和氧饱和曲线的差别;研究了有无叠氮钠、黄嘌呤-黄嘌呤氧化酶介导下,血红蛋白和阿魏酸修饰的血红蛋白的自氧化速率的改变。结果表明,阿魏酸修饰血红蛋白,保持了血红蛋白的功能结构,仍具备血红蛋白的载氧活性,有效降低了自氧化速率。     

血红蛋白在膜分离过程中的氧化规律和抗氧化探索

脱离了红细胞的血红蛋白(Hb)在溶液中易被氧化成高铁血红蛋白(MetHb),失去载氧活性. 实验发现,当对红细胞裂解液进行微孔膜分离时,高铁血红蛋白增加不多;但在用层析法去除超氧化物歧化酶等其他红细胞蛋白后再进行超滤膜浓缩血红蛋白时,则出现较多的血红蛋白被氧化成高铁血红蛋白的现象,其氧化反应随超滤过程膜表面流体切向速度的增加而加快,随溶液温度的增加而加快. 抗氧化剂的存在能有效地降低高铁血红蛋白的生成,谷胱甘肽(GSH)、半胱氨酸、N-乙酰半胱氨酸、亚硫酸钠、抗坏血酸(Vc)在溶液中和超滤过程中都能起到对血红蛋白载氧活性的保护作用. 其中Vc的效果最好,最适加入量(摩尔比)Vc/Hb=8, pH 8. 将抗氧化的优化条件整合到从红细胞裂解液开始到超滤浓缩血红蛋白的整个流程,在离子交换层析后,添加Vc作为抗氧化剂进行超滤浓缩,Hb活性得到了很好的保护,MetHb的含量控制在2.3%,成功地制备了低MetHb含量的纯化血红蛋白.     

乙二醇二缩水甘油醚交联血红蛋白的反应优化

将乙二醇二缩水甘油醚(EGDE)作为血红蛋白(Hb)的交联剂制备红细胞代用品.采用SDS-PAGE电泳、高效液相色谱和多角度激光散射检测器联用鉴定交联产物.实验表明,在pH 8.7,血红蛋白浓度为20 mg·mL-1,修饰剂EGDE与血红蛋白的摩尔比达100:1时反应4 h,交联产物中90%为分子内交联的血红蛋白.在pH 7.5、血红蛋白浓度为200mg·mL-1,修饰剂EGDE与血红蛋白的摩尔比为25:1时反应12 h,交联产物主要为寡聚血红蛋白,分子量范围在145-375 kD之间;其中二聚体血红蛋白占总蛋白量的74.7%,三聚体血红蛋白18.9%,四到六聚血红蛋白6.4%,几乎无高聚物生成.采用血氧分析仪对交联产物进行活性鉴定,制备的分子内交联和寡聚血红蛋白均具有携氧能力,小鼠的生物学实验表明产品无异常毒性,具备了作为红细胞代用品的可能性.     

磷酸银掺杂WO_3-TiO_2复合材料的制备及其光催化降解性能

以钛酸四丁酯作前体,采用溶胶-凝胶法和水热法分别制备TiO_2、WO_3-TiO_2和Ag_3PO_4-WO_3-TiO_23种催化剂,用XRD、SEM、FTIR和BET进行表征,考察在可见光(λ> 420 nm)下降解罗丹明B的光催化活性。结果表明,WO_3和Ag_3PO_4负载在TiO_2上,Ag_3PO_4的修饰可以协同WO_3共同抑制TiO_2晶粒生长。Ag_3PO_4-WO_3-TiO_2复合材料为介孔型结构,修饰后比表面积增大。当p H=7时,550℃煅烧制得复合材料光催化活性最高(样品中WO_3摩尔百分含量为1%,m(Ag_3PO_4)∶m(WO_3-TiO_2)=1∶5),70 min后罗丹明B的光催化降解率达到95. 0%。且重复使用5次后,光催化活性无明显下降,降解率仍保持在90%以上,催化剂具有很高的稳定性。     

磷酸银掺杂WO_3-TiO_2复合材料的制备及其光催化降解性能

以钛酸四丁酯作前体,采用溶胶-凝胶法和水热法分别制备TiO_2、WO_3-TiO_2和Ag_3PO_4-WO_3-TiO_23种催化剂,用XRD、SEM、FTIR和BET进行表征,考察在可见光(λ> 420 nm)下降解罗丹明B的光催化活性。结果表明,WO_3和Ag_3PO_4负载在TiO_2上,Ag_3PO_4的修饰可以协同WO_3共同抑制TiO_2晶粒生长。Ag_3PO_4-WO_3-TiO_2复合材料为介孔型结构,修饰后比表面积增大。当p H=7时,550℃煅烧制得复合材料光催化活性最高(样品中WO_3摩尔百分含量为1%,m(Ag_3PO_4)∶m(WO_3-TiO_2)=1∶5),70 min后罗丹明B的光催化降解率达到95. 0%。且重复使用5次后,光催化活性无明显下降,降解率仍保持在90%以上,催化剂具有很高的稳定性。     

高氮含量钠杂氮团簇的生成与检测

为了将NaN3及NaN3分别与BN、ZrN、Ti混合粉末(摩尔比1∶1)经压片机制成直径为13mm、厚度为2~5mm的底物,使用高纯氮气为反应气体和载气,采用液氮冷却离子源,经激光溅射生成了钠杂氮团簇NaNn+(n=2、4、5、6、7、8、9、10、11、12),采用反射式飞行时间质谱仪检测并获得了其质谱图。结果表明,不同底物生成的钠杂氮团簇具有不同特点,激光溅射NaN3和NaN3/BN混合物分别生成了4种钠杂氮团簇NaN+n(n=2、4、6、8),但是其离子峰相对强度随氮原子数变化的趋势不同;激光溅射NaN3生成的钠杂氮团簇离子峰相对强度随氮原子数从2到6逐渐增高,到8时降低,而激光溅射NaN3和NaN3/BN混合物生成的钠杂氮团簇离子峰的相对强度随氮原子数增加单调下降;激光溅射NaN3/ZrN混合物生成了不同于NaN3和NaN3/BN混合物的钠杂氮团簇NaN+10和NaN4(H2O)+,最大氮原子数达到10。其中以NaN3/TiN混合样品为底物生成的钠杂氮团簇NaNn+种类最多、含氮量最高,氮原子数最多的团簇为NaN12+,NaN12+的含氮质量百分数达到约88%。     

氮镱共掺杂TiO2介孔材料的制备及光催化降解生活污水

以尿素和硝酸镱分别作为氮源和镱源,用溶胶-凝胶法制备氮、镱共掺杂TiO2光催化剂.通过X射线衍射(XRD)、傅立叶变换红外光谱(FT-IR)、扫描电子显微镜(SEM)、能量分散X射线能谱(EDX)等分析手段表征产品结构和光学性能.考察了光照时间、pH、催化剂中含氮摩尔百分量等因素对光催化降解生活污水的影响.结果表明,经紫外光照射4 h,体系的pH=4、氮与钛的摩尔百分比为3时,对生活污水的光降解效果最好,COD去除率可达79.6%,色度去除率达到100%.     

树形高分子增强的高分子磁性颗粒的制备与表征

利用化学共沉淀法制备Fe3O4磁性纳米粒子;悬浮聚合的方法制备带有酰胺基的聚苯乙烯-丙烯酰胺磁性颗粒(NMP);发散法制备聚酰胺胺树形高分子(PAMAM)并与酰胺修饰聚苯乙烯磁性颗粒结合,得到树形高分子增强的磁性微粒。并对NMP和PAMAM-NMP的颗粒基质晶体结构、饱和磁化强度、表面官能团和微观结构以及各元素的百分含量进行表征。结果显示,Fe3O4磁核晶形完整,平均粒径为9 nm;PAMAM-NMP的红外图谱在3478 cm-1和3 300 cm-1处有吸收峰,证明存在胺基;经PAMAM增强后氮元素百分含量由0.225%增加到0.992%,证明PAMAM为NMP提供了更多的活性基团;在有无磁场存在时的沉淀时间分别为16 h和2112 h,证明PAMAM-NMP有良好的磁响应性和悬浮性。     

氮杂环丁烷类药物中间体的合成

以1-叔丁氧羰基-3-羟基氮杂环丁烷为原料,叠氮化钠和邻苯二甲酰亚胺钾盐为氨源,考察了两种途径合成1-叔丁氧羰基-3-氨基氮杂环丁烷这种药物中间体实验的可操作性、安全性能、产率高低和后处理的繁简。实验表明,当用叠氮化钠为氨源取代羟基成叠氮基时,经过分批加入锌粉可还原成伯氨,得到70%的产率。但是叠氮化钠毒性较强,受热或震动摩擦可发生爆炸,操作难度较大。当用邻苯二甲酰亚胺钾盐为氨源,生成的叔氨在乙醇水合肼溶液中加热回流肼解生成伯氨,产率为63%。产率虽然低于前一种方法,但是实验的可操作性很强,安全且后处理简单。     

Autoxidation of fatty materials in emulsion. II. Factors affecting the histidine-catalyzed autoxidation of emulsified methyl linoleate

Several factors which affect autoxidation of methyl linoleate in emulsion have been examined. Data are presented which indicate: 1) In the presence of histidine, the ionic (anionic) emulsifiers examined promote autoxidation of emulsified methyl linoleate, but nonionic emulsifiers do not. 2) The concentration of an emulsifier affects the rate of oxygen absorption. 3) Inorganic salts (0.1 M or less) such as sodium chloride, sodium acetate and sodium sulfate affect oxygen absorption of emulsified methyl linoleate prepared with either ionic or nonionic emulsifiers. In histidine-catalyzed autoxidation there is a suppressing effect in the case of the ionic and a promotional effect in the case of the nonionic. In uncatalyzed autoxidation, these salts have a promotional effect in ionic emulsions and none in nonionic emulsions. 4) Sodium phosphate buffers completely suppress autoxidation due to histidine catalysis, but do not suppress the normal uncatalyzed autoxidation of emulsified methyl linoleate. 5) The pro-oxidative effects of histidine and histidine-metal ion complexes on emulsified unsaturated materials is not limited to polyolefins but also includes mono-olefinic compounds. Presented at the AOCS meeting in Toronto, October, 1962. E. Utiliz. Res. and Dev. Div., ARS, USDA.     

1-苄基-4-（4-甲氧基）-苯基-1，2，3-三唑的合成

采用氯苄和叠氮化钠在乙醇中反应制备了苄叠氮,进而与对甲氧基苯乙炔进行1,3-偶极环加成反应合成了未见报道的1-苄基-4-（4-甲氧基）-苯基-1,2,3-三唑,产率达到了48％,产物结构经NMR和MS确认。     

叠氮化钠合成法方法现状及发展

当今国内外对叠氮化钠的需求量增加,而现有制造技术相对不足且产能较低,对现有4种合成叠氮化钠的主要方法:钠法、水合肼法、尿素法和硝基胍法进行总结归纳并得出一种新的制法:先制得叠氮基团,再将钠离子与叠氮基团结合生成叠氮化钠,最后根据需要进行提纯。     

1-溴-5-苯基-四氮唑的合成

以苯甲腈、叠氮钠、溴等为原料,经偶合,溴化合成了1-溴-5-苯基四氮唑。研究了反应时间、反应温度、溶剂与反应物配比对产品收率的影响。实验表明:在n(苯甲腈)∶n(叠氮钠)=1∶1.1,1 mol NH4Cl催化,120℃下反应20 h可得到收率90%的5-苯基四氮唑。在n(5-苯基四氮唑)∶n(溴)∶n(氢氧化钠)=1∶0.97∶0.96,反应4 h,水作溶剂的条件下,可得到56.4%的1-溴-5-苯基四氮唑,两步反应后的总收率为49.1%。     

Synthesis of well defined amino telechelic cis-1,4-oligoisoprenes from carbonyl telechelic oligomers; first studies of their potentialities as polyurethane or polyurea materials precursors

Carbonyl telechelic cis-1,4-oligoisoprene (CTPI) obtained from high molecular weight polyisoprene through an oxidative chain cleavage reaction have been chemically modified. Thus, new well defined amino telechelic cis-1,4-oligoisoprenes have been obtained in a mass range of 1600-2300 g/mol according to two different pathways. The first approach involved a standard mesylate displacement by sodium azide followed by smooth reduction using triphenylphosphine. The second pathway implied a reductive amination sequence. Primary or secondary amine functions have thus been selectively obtained at both oligomer chain-ends depending on reaction conditions. Peculiar NMR experiments conducted on these functional oligomers confirmed a precise control of functionality during the chemical modification. Moreover, their abilities to react with toluene diisocyanate or bis(succinimidyl)carbonate have been investigated.     

Immobilization of enzymes onto modified polyacrylonitrile membranes: Application of the acyl azide method

Chemical reactions toward acyl azide activated polyacrylonitrile (PAN) and conditions for membrane surface modifications are described. Ultrafiltration (UF) membranes were prepared from PAN homopolymer and copolymer with methyl acrylate. Besides hydrazide formation and nitrosation, a new method to introduce acyl azide groups into carboxyl modified PAN, using azido transfer with diphenyl phosphoryl azide, was developed. Chemical conversions were characterized, especially with Fourier transform infrared spectroscopy. The heterogeneous modifications are not chemically selective due to side reactions and/or incomplete conversion. The pore structure is altered predominately via modified polymer swelling causing changed UF fluxes and selectivities. However, for the modification via PAN reaction with hydroxyl amine, acid hydrolysis, and azido transfer, the initial membrane separations performance is qualitatively preserved. Using the acyl azide ḿethod, amylo-glucosidase (AG) (EC 3.2.1.3) was immobilized onto the modified PAN UF membranes, enabling hydrolysis of starch or maltose to glucose. Enzyme activity was assayed depending on previous chemical modification (azide content) and immobilization (pH) conditions as well as hydrolysis parameters (substrate, conversion during diffusion or UF). The best results (up to 600 mU/cm² at 40°C and pH 5.0) were obtained after modification of PAN membranes via carboxyl creation and azido transfer. AG convalently bound to PAN is not influenced much in its catalytic properties (K_m = 3.48 and 3.1 mmol/L for free and bound AG, respectively, with maltose at 40°C and pH 5.0). Under UF conditions, AG effective activity can be improved by the convective flow through the membrane. UF selectivity for the polymer starch determines effective substrate concentrations in the membrane, thus affecting observed activities and product purities in the filtrate. © 1996 John Wiley & Sons, Inc.     

Photocrosslinking of azidated poly(vinyl chloride) coated onto plasticized PVC surface: Route to containing plasticizer migration

The migration of phthalate esters which are commonly employed for plasticizing poly(vinyl chloride) (PVC) is a significant problem in PVC-based medical devices as well as in packaging used for food stuffs and pharmaceuticals. Medical-grade PVC resin was treated with sodium azide in dimethylformamide (DMF) to prepare the azide polymer. The polymeric azide was coated onto the surface of plasticized PVC sheets by dipping in a solution of the polymer in tetrahydrofuran (THF). Crosslinking of the azide polymer was accomplished by irradiating the surface using a 125 W UV lamp for various lengths of time. Migration of the plasticizer di 2-(ethylhexyl phthalate) (DEHP) from coated and uncoated samples was examined in n-hexane at 30°C. It was found that 50–80% reduction in migration of DEHP could be effected from plasticized PVC in comparison with the controls in 72 h by this technique depending on the concentration of the coating solution, coating thickness, azide concentration, and irradiation dose. © 1995 John Wiley & Sons, Inc.     

Orthogonal array design method for optimization experiments of sodium azide microencapsulation with stearic acid

In this study, an orthogonal array design (OAD), OA₉, was employed as a statistical experimental method for mircoencapsulation of sodium azide with stearic acid through a solvent/non-solvent procedure which is based on the coacervation principle. Scanning electron microscopy (SEM) was used to examine the coating morphology. The effect of stearic acid coating on sodium azide decomposition has been studied by means of differential thermal analysis (DTA), thermogravimetry (TG) and differential scanning calorimetry (DSC). Our findings revealed that stearic acid can provide an effective coating shell around sodium azide microparticle and the coating quality is affected by some parameters, such as percent of stabilizer, addition time of non-solvent, volume of non-solvent and stirring speed of the mixture (revolutions per minute, rpm). The effects of these factors on the thermal decomposition temperature of microencapsulated sample were quantitatively evaluated by the analysis of variance (ANOVA). The statistical results showed that sodium azide powder can optimally be coated and stabilized by controlling of stabilizer percent, addition time of non-solvent, and volume of non-solvent. The OAD evaluation of initial experimental data provide optimized amount of the parameters to obtain the most stabilized sample, at which the thermal decomposition temperature of sodium azide is predicted at 436 °C. The prediction is in excellent agreement with experimental result obtained at the same conditions that is 435 °C. These data could be compared to that of the pure stearic acid and sodium azide in which decomposition temperature ranges are 160–300 and 382–397 °C, respectively. Also, the kinetic parameters such as activation energy and frequency factor of the decomposition processes of pure components and microencapsulated sodium azide at optimum condition were obtained from the DSC data by non-isothermal methods proposed by ASTM E696. Our finding showed that the treated NaN₃ has much lower decomposition rate as compared to the pure one.