表面张力法研究温敏性接枝共聚物的微胶束化行为

用表面张力法研究了以水溶性可生物降解的葡聚糖为主链 ,具有温敏相变特性的聚 (N 异丙基丙烯酰胺 )为接枝链的葡聚糖 接枝 聚 (N 异丙基丙烯酰胺 ) (Dextran g PNIPAM)共聚物在水溶液中的胶束化行为 .研究结果表明Dextran g PNIPAM体系的微胶束化行为与共聚物结构和溶液体系的温度密切相关 ,接枝共聚物中PNIPAM含量越大 ,水溶液体系的温度越高 ,形成胶束的临界胶束浓度 (CMC)越小 .特别值得指出的是 ,无论水溶液的温度是否高于PNIPAM接枝链段的相变温度 (LCST) ,即PNIPAM链段由亲水性转变为疏水性的温度 ,Dextran g PNIPAM均呈现一个临界胶束浓度大 ,对该现象给予了解释 .     

侧链含咪唑取代基聚(L-天冬酰胺)高效基因载体研究

通过氨基引发聚丁二酰亚胺( PSI)开环反应,制备了系列侧链含氨乙基和咪唑丙基的聚(L-天冬酰胺)共聚物(P1 ～ P5).该系列聚合物不仅具有极低的细胞毒性,而且随侧链中咪唑取代基含量的增加,聚合物在pH 5 ～8范围内缓冲能力显著提高.通过凝胶电泳、粒径和电位分析等研究了聚合物与质粒DNA的相互作用.结果表明,所有...     

聚膦腈-g-聚己内酯共聚物的合成与表征

通过三甲基碘硅烷与聚二(2-甲氧基乙氧基)膦腈侧链上的醚键反应后水解得到侧链含部分羟基的聚膦腈,然后利用聚膦腈的侧链羟基在异辛酸亚锡催化作用下,引发己内酯单体开环聚合制备了聚膦腈-g-聚己内酯共聚物.该共聚物中聚己内酯链段的接枝率和侧链长度可通过改变三甲基碘硅烷和己内酯单体的投料来控制.     

聚乳酸-b-聚(N~ε-苄氧羰基-L-赖氨酸)-b-聚乙二醇的合成与表征

用端氨基聚乳酸做引发剂,在DMF中引发Nε-苄氧羰基-L-赖氨酸酐(Lys(Z)-NCA)聚合,合成了端氨基聚(Nε-苄氧羰基-L-赖氨酸)-b-聚乳酸两嵌段共聚物.以端羧基聚乙二醇经NHS活化与端氨基聚(Nε-苄氧羰基-L-赖氨酸)-b-聚乳酸偶联,合成了聚(乳酸-b-Nε-苄氧羰基-L-赖氨酸-b-乙二醇)三嵌段聚合物.利用IR、1H-NMR、GPC和TEM对它们的结构、形态进行了表征,结果表明,所合成的分子量可控、分子量分布窄(Mw/Mn=1.07)的嵌段共聚物,酰化反应产率达70%以上.同时聚乙二醇和Nε-苄氧羰基-L-赖氨酸被引入到聚乳酸主链中,在聚合物侧链脱保护后有望改善聚乳酸的细胞亲和性。     

N-异丙基丙烯酰胺类共聚物温敏性研究

制备了N-异丙基丙烯酰胺(NIPAAm)与N,N-二甲基丙烯酰胺(DMAAm)和/或甲基丙烯酸羟乙酯(HEMA)的二元及三元共聚物,研究了组成和链转移剂用量对共聚物温敏性的影响,并在上述三元共聚物上接枝聚己内酯(PCL)得到温敏性两亲聚合物.结果表明,随着DMAAm增加、HEMA减少或共聚物分子量降低,共聚物的最低临界溶解温度升高,且PCL链段的接枝度和长度对聚合物的温敏性影响明显.     

聚L-丙氨酸-聚乙二醇嵌段共聚物的胶束化行为研究

以氨基聚乙二醇单甲醚(MPEG-NH₂)为大分子引发剂, 采用开环聚合方法合成了聚L-丙氨酸-聚乙二醇嵌段共聚物(PAME), 并对其结构进行了表征; 用圆二色谱(CD)研究了嵌段共聚物在水溶液中的二级结构, 用芘荧光探针技术研究了共聚物胶束的形成及其临界胶束浓度(CMC), 利用动态光散射(DLS)和透射电镜(TEM)研究了胶束的粒径分布和形态. 结果表明, 在水溶液中共聚物链以α-螺旋构象形式存在, 在一定条件下嵌段共聚物能够形成球形的稳定胶束, PAME-1形成胶束的CMC为1.99×10^-5 mol/L, CMC值受共聚物中聚L-丙氨酸(PLA)链段含量的影响.     

聚氨基酸接枝聚异戊二烯的仿生合成与性能

通过硫醇-烯点击反应将2-氨基乙硫醇接枝到聚异戊二烯主链上合成带有氨基侧链的聚异戊二烯,再通过侧链氨基引发L-缬氨酸-N-硫代羧基内酸酐(Val-NTA)单体和β-苯丙氨酸-N-硫代羧基内酸酐(β-Phe-NTA)单体的聚合,制备出2种方式改性的聚异戊二烯.其中,Val-NTA聚合接枝聚异戊二烯的拉伸强度28.6 MPa,300%定伸强度18.9 MPa,相比天然橡胶分别提升10.7%和9.3%. β-Phe-NTA聚合接枝聚异戊二烯的拉伸强度28.0 MPa,比天然橡胶提升8.3%.     

聚L-丙氨酸-聚乙二醇嵌段共聚物纳米胶束的研究

分别以氨基聚乙二醇和氨基聚乙二醇单甲醚为大分子引发剂,采用开环聚合的方法合成了两亲性聚L-丙氨酸-聚乙二醇(PAE)和聚L-丙氨酸-聚乙二醇单甲醚(PAME)两种嵌段共聚物,其结构经1H NMR,IR,DSC,GPC等表征;利用园二色技术研究了其在水溶液中的二级结构,用芘荧光探针技术研究了其胶束的形成及其临界胶束浓度(CMC),利用透射电镜研究了胶束的形态。结果表明,在水溶液中共聚物链以α-螺旋构象形式存在,在一定条件下嵌段共聚物PAE-1,PAE-2,PAME-1和PAME-2能够形成球形的稳定胶束,PAE-1形成胶束的CMC为3.36×10-5mol.L-1,CMC值受嵌段类型和共聚物中聚L-丙氨酸链段含量的影响。     

淀粉-磺甲基化聚丙烯酰胺接枝共聚物的合成及性能

用淀粉-聚丙烯酰胺接枝共聚物(S-g-PAM)同多聚甲醛及亚硫酸钠反应,合成了淀粉-磺甲基化聚丙烯酰胺接枝共聚物(S-g-SPAM)。该磺化物的水溶液在试验浓度范围内(0.1～1.0％),为假塑性流体,对高岭土悬浮液的絮凝,由沉降速度,上层清液相对吸光度可知,S-g-SPAM(接枝链分子量为1.03×10⁵,磺甲基化度30％)的絮凝能力优于相应的未磺化的S-g-PAM,也比聚丙烯酰胺(分子量2.5×10⁶)强。     

大豆分离蛋白接枝氨基封端聚2-丙烯酰胺基-2-甲基丙磺酸的合成及溶液性质研究

用巯基乙胺为链转移剂,过硫酸铵为引发剂合成了氨基封端的聚2-丙烯酰胺基-2-甲基丙磺酸(H2N-PAMPS).再用1-(3-二甲氨基丙基)-3-乙基碳二亚胺盐酸盐(EDC)和N-羟基琥珀酰亚胺(NHS)在室温下催化H2N-PAMPS的端氨基与大豆分离蛋白(SPI)的羧基反应形成酰胺键,得到接枝物SPI-g-NH-PAMPS.用1H-NMR、傅利叶红外光谱、13C-NMR对H2N-PAMPS和接枝物SPI-g-NH-PAMPS进行结构表征.用zeta电位仪、紫外可见光光谱,荧光光谱,动态激光光散射对SPI及其接枝物SPI-g-NH-PAMPS的水溶液性质进行了研究.结果表明,与SPI相比,SPI-g-NH-PAMPS的溶解性、表面疏水性、乳化性等有所改善,接枝物SPI-g-NH-PAMPS聚集体粒径增大,形成独特的核壳结构.     

多重聚合酶链反应-毛细管电泳-激光诱导荧光法检测三种食源性致病菌

建立了食品中常见致病菌大肠杆菌O157:H7的uidA基因、沙门菌的invA基因和志贺菌的ipaH基因的多重聚合酶链反应（PCR）产物的毛细管电泳快速检测方法。根据这3种致病菌的特异性基因序列设计多重PCR引物,优化PCR扩增反应体系,采用7.0 g/L 甲基纤维素为筛分介质,毛细管电泳-激光诱导荧光检测法同时检测了3种常见致病菌的PCR扩增产物。在优化的多重PCR反应和毛细管筛分电泳条件下,该方法可以同时检测沙门菌、志贺菌和大肠杆菌O157:H7基因的多重PCR扩增产物,22 min内即可完成3种常见致病菌的毛细管电泳检测。迁移时间的相对标准偏差为1.47%~2.07%。与凝胶电泳法比较,该法简便快速,灵敏度高,可用于多种致病菌脱氧核糖核酸的检测,为食品安全提供了一种可靠的快速检测方法。     

Free mobility determination by electrophoresis in polyacrylamide containing agarose at a nonrestrictive concentration

In the determination of the free mobility, related to the surface net charge, by quantitative gel electrophoresis, the previous arbitrary extrapolation of Ferguson plots from the lowest gel concentrations that give a mechanically stable gel to 0% T has recently been replaced by measurement of mobilities across that concentration range, using the addition of 0.5% agarose to polyacrylamide at the various low concentrations in application to a DNA fragment 155 bp in size (Orbán, L. et al., in preparation). The present study applies that approach to several proteins and DNA fragments smaller than 1300 bp, using 0.4% agarose in polyacrylamide gels of varying concentration. The intercepts of the plots with the mobility axis provide experimental data by which the free mobility in polyacrylamide gel electrophoresis can be estimated for molecules not significantly retarded in their migration at the agarose concentration admixed to polyacrylamide. Across the gel concentration range below 3% T, in the presence of agarose, the Ferguson plots of proteins and DNA fragments are convex. It was shown by mass spectrometry that this convex curvature of the plots in the mixed polymer is not significantly due to low polymerization efficiency in the concentration range of liquid polyacrylamide (below 3%T).     

Novel Naphthalimide Derivatives as Selective G-Quadruplex DNA Binders

A new derivate of 4-bromo-1,8-naphthalic anhydride and its quaternized analogue have been prepared and characterized. The interactions of both derivatives with human telomere quadruplex-DNA and ds-DNA have been comparatively studied by UV-visible (UV-Vis), fluorescent intercalator displacement assays, competition dialysis, circular dichroism (CD), agarose gel electrophoresis, and polyacrylamide gel electrophoresis. The results show that both derivatives can stabilize G-quadruplexes DNA, and they show different binding affinities for G-quadruplexes-DNA and ds-DNA. All spectroscopic studies have shown that the derivatives have a modest selectivity for G-quadruplex versus ds-DNA.     

Effect of linear polymer additives on the electroosmotic characteristics of agarose gels in ultrathin-layer electrophoresis.

Electroosmotic properties of agarose gels with low, medium, high and super high electroendosmosis (EEO) were evaluated based on the apparent electric field mediated mobility of a neutral, fluorescent marker under constant field strength using ultrathin-layer separation configuration. Electroosmotic flow mobility values were measured in different gel concentrations and also in the absence and the presence of various linear polymer additives. Under ultrathin-layer separation conditions, a slight decrease in electroosmotic flow mobility was observed with increasing agarose gel concentration of 1 to 3% for all agarose gels investigated. When linear polymer additives, such as linear polyacrylamide, hydroxyethyl cellulose or polyethylene oxide were added to 1% low electroendosmosis agarose gel, significant reduction of the electroosmotic flow properties were observed with increasing additive concentration. Effect of the intrinsic electroosmotic properties of the various electroendosmosis agaroses on the apparent mobilities and separation performance of double-stranded DNA fragments during automated ultrathin-layer agarose gel electrophoresis was also investigated.     

DNA在羧基功能化吡咯共聚物导电薄膜上的固定/杂交行为

将(N-吡咯)己基硫醇自组装在金膜上,并采用化学氧化聚合法使吡咯与羧基功能化吡咯衍生物在自组装薄膜上进行共聚.然后对共聚物进行羧基活化处理.探针DNA通过与共聚物膜之间的共价键作用而固定在其表面上,接着与靶向DNA杂交.同时采用傅立叶红外变换光谱仪和X-射线光电子能谱仪对共聚物在DNA固定前后的化学组成进行详细表征.采...     

Polycationic graft copolymers of poly(N-vinylpyrrolidone) as non-viral vectors for gene transfection

Novel graft copolymers of 2-(dimethylamino)ethyl methacrylate (DMAEMA) with N-vinylpyrrolidone (NVP) were designed and synthesized by the free radical copolymerization of DMAEMA with precursor polymers of vinyl-functionalized poly(N-vinylpyrrolidone) (PVP). The ability of the PVP- grafted copolymers to bind and condense DNA was confirmed by ethidium bromide displacement assay, agarose gel electrophoresis and transmission electron microscopy. The presence of PVP in the copolymers had a favorable effect on the biophysical properties of polymer/DNA complexes. Colloidal stable complexes obtained from the copolymer systems, were shown to be separate, uniformly spherical nanoparticles by transmission electron microscopy. The approximate diameter of the complexes was 150–200 nm, as determined by dynamic light scattering studies. These results confirm an important role played by the PVP grafts in producing compact stable DNA complexes. The ζ-potential measurements revealed that the incorporation of the PVP grafts reduced the positive surface charge of polymer/DNA complexes. The cytotoxicity of the copolymers decreased with an increasing fraction of PVP. Furthermore, in vitro transfection experiments with these copolymers showed improved ability of transfection in cell culture, demonstrating an important role for PVP grafts in enhancement of the transfection efficiency.      

Novel amphiphilic fluorescent graft copolymers: synthesis,characterization, and potential as gene carriers

Amphiphilic fluorescent graft copolymer (PVP‐PyATAm) was successfully synthesized by the free radical copolymerizations of hydrophobic monomer N‐acryloyl‐thioureylene‐4‐(1‐pyrene)‐butyryl amide (PyATAm) with hydrophilic precursor polymers of vinyl‐functionalized poly (N‐vinylpyrrolidone) (Acryloyl‐PVP) in DMF. FT‐IR, ¹H NMR, TEM, gel permeation chromatography‐multi‐angle laser light scattering, UV‐vis spectroscopy, viscometric measurement, and fluorescence spectroscopy were used to characterize this copolymer. The TEM observation showed that the copolymer PVP‐ PyATAm formed spherical micelles in an aqueous solution and the size of micelles was between 50 and 70 nm in diameter. The interaction of PVP‐PyATAm copolymer and plasmid DNA was examined by agarose gel electrophoresis and TEM. Results indicated that the copolymer–DNA complexes were self‐assembled and the size of complexes was between 90 and 120 nm in diameter. Cytotoxity studies using MTT colorimetric assays suggested good biocompatibility of PVP‐PyATAm in vitro. These results suggested the potential of this graft copolymer as gene delivery carrier. Copyright © 2007 John Wiley & Sons, Ltd.     

Polypropylene/polystyrene blends: In situ compatibilization by Friedel‐Crafts alkylation reaction

The application of Friedel‐Crafts alkylation reaction to the compatibilization of polypropylene (PP)/polystyrene (PS) blends was assessed. A PP macrocarbocation is chemically bonded to the PS benzene ring by aromatic electrophilic substitution. The graft copolymer formed at the interphase (PP‐g‐PS) showed relatively high emulsification strength, suggesting an effective behavior as in situ compatibilizer. The critical micelle concentration (CMC) was related to Friedel‐Crafts catalyst concentration. The amount of PS grafting and possible appearance of crosslinking and chain scission side reactions were also analyzed. The reaction products were characterized by a combination of size exclusion chromatography and Fourier transform infrared techniques applied after a careful solvent extraction separation. It was found, from the emulsification curve, that CMC was achieved when 0.7 wt % AlCl₃ was added. This value was confirmed by scanning electron microscopy observation of phase adhesion on fractured sample surfaces. Mass balances of extracted PS showed that at least 15 wt % of the initial PS resulted grafted at the CMC condition. Chain scission reactions, in parallel with grafting, were verified to occur for PP as well as for PS. Instead, crosslinking reactions were not detected. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 452–462, 2004     

Advances in DNA electrophoresis in polymer solutions.

DNA electrophoresis in gels and solutions of agarose and polyacrylamide was objectively evaluated with regard to separation efficiency at optimal polymer concentrations. In application to DNA fragments, polyacrylamide gels were superior for separating fragments of less than 7800 bp, and agarose gels are the best choice for larger fragments. Agarose solutions are nearly as good as polyacrylamide gels for small DNA (< 300 bp). Agarose solutions have a higher efficiency than polyacrylamide solutions for DNA of less than 1200 bp. Separation efficiency sharply decreases with increasing length of DNA. Retardation in polyacrylamide solutions was found to depend on polymer length in a biphasic fashion. The choice of resolving polymer concentrations depends on the progressive stretching of DNA in proportion to polymer concentration. The rate of that stretching appears higher in polyacrylmide solution than in gels or in liquid or gelled agarose. Application of polymer solutions to capillary electrophoresis raises further problems concerning agarose plugs, DNA interactions with the polymers, operation at low field strength and long durations as well as detection sensitivity.     

具有电活性苯胺四聚体接枝聚谷氨酸的合成与表征

以N-羟基琥珀酰亚胺(NHS)活化聚L-谷氨酸的羧基并与苯胺四聚体的氨基缩合,得到了以可生物降解的聚谷氨酸为主链,具有电活性的苯胺四聚体为侧链的新型接枝聚合物.用1H-NMR、质谱分析、光谱分析的方法确定了化合物的结构.侧链羧基的存在使聚合物可以溶解于碱性的缓冲溶液中.对聚合物的电化学性质进行了紫外及循环伏安的表征,研究结果表明,接枝后的聚合物具有与苯胺低聚体相似的可逆的氧化还原过程并可被质子酸掺杂,表现出良好的电化学活性.同时,以定量紫外吸收及元素分析的方法分别测定了聚合物的接枝率.实验中通过控制反应的投料比可以使苯胺四聚体的接枝率达到40%以上,并对聚合物的自掺杂现象进行了讨论.