P(DEAM-co-MAA)在稀水溶液中构象行为的荧光探针研究

利用UV透光率测定,荧光探针技术等研究了N,N-二乙基丙烯酰胺(DEAM)与甲基丙烯酸(MAA)的共聚物P(DEAM-co-MAA) 在稀水溶液中的构象行为.结果表明，当共聚物中DEAM含量小于8.00％(molar fraction),溶液的pH < 6时,P(DEAM-co-MAA)在稀水溶液中的构象行为与聚甲基丙烯酸(PMAA)相似,共聚物可形成疏水微区,表现为一种较为高度压缩的线团构象;当共聚物中DEAM含量大于8.00％(molar fraction)时,由于高分子的稀释效应,P(DEAM-co-MAA)在pH 2～10范围内表现为较为松散的伸展构象.P(DEAM-co-MAA)构象随其组成和pH变化的这种性质有可能在新型敏感性凝胶的合成设计上获得应用.     

新型荧光双重敏感响应性壳聚糖衍生物的合成及其发光性能研究

为了开发新型多功能天然高分子荧光材料，合成出一种新型含有环氧丙氧基荧光素(EPF)基团的水溶性壳聚糖衍生物GCS-EPF, 并用IR，1H NMR，UV光谱和荧光光谱等手段进行结构和发光性能的研究. 结果表明, 修饰后水溶性壳聚糖(GCS)的水溶液、 固体粉末和薄膜在520 nm附近具有较强的荧光发射, 其荧光强度不仅在0-60 ℃时对度有较快敏感响应， 同时在pH=0-13.5时对pH也有较快敏感响应， 具有双重敏感响应, 因此可将其作为温度荧光探针和pH荧光探针的高分子材料.     

水溶性芴与噻吩共聚物的合成及蛋白质对其荧光猝灭的影响

采用Suzuki偶合方法合成了含羧酸基团的新型阴离子型水溶性绿光的9,9’-二丙酸钠芴(DPF)和噻吩(TH)共聚物,聚合物分子量约为9000左右,具有较好的水溶性(5 mg/mL).研究了共聚物在不同pH水溶液中的荧光性质,结果表明当pH ＜4时,羧基以COOH形式存在,造成共聚物溶解度降低并产生聚集,荧光减弱;当p...     

水杨醛衍生物激发态下的质子转移过程及在荧光探针领域的应用

从电子结构控制理论出发,通过在酚羟基对位引入吸电子取代基团稳定水杨醛中激发态的酮式构象,制备了目标化合物5-对氰基苯基-水杨醛(CN-SA).光谱测试结果显示,CN-SA表现出典型的ESIPT态荧光分子特性,而且辐射跃迁过程的酮式分配比例显著提高,荧光强度和颜色变化明显.CN-SA的荧光光谱不但能够对外围溶剂环境进行选择性识别,而且对溶解和聚集过程(聚集效应)及外围氢键形成能力的变化(pH效应和阴离子效应)等具有特异性响应,其变化可以定量表达.CN-SA仅通过结构微调即实现醇-酮构象的显著变化,可作为一个简单的多重刺激响应型荧光探针.     

间位聚亚吡啶基亚乙炔基共轭聚电解质的合成与溶液光物理性质

合成了单体1,4-双(3-磺酰化丙氧基)-2,5-二碘苯与2,6-二乙炔基吡啶,利用Heck-Sonogashira偶联反应制备了间位聚亚吡啶基亚乙炔基共轭聚电解质m-PPYPE-SO3Na,对单体以及聚合物进行了红外光谱与核磁氢谱表征.测试了该共轭聚电解质m-PPYPE-SO3Na的紫外-可见吸收光谱与荧光发射光谱.研究了该共轭聚电解质的溶液光物理性质,发现该聚电解质具有荧光发射的溶剂依赖性以及浓度依赖性,在水溶液中存在聚集.在聚合物溶液浓度为1×10-6mol/L左右时,聚集发射基本消失,说明此时在溶液中聚合物的聚集程度已经比较低.该聚电解质在水溶液中与表面活性剂之间存在一定的相互作用,加入非离子型高分子表面活性剂聚乙烯吡咯烷酮(PVP)的聚合物水溶液荧光显著增强,表明该表面活性剂破坏聚电解质的聚集.该共轭聚电解质的溶液光物理性质表明其具有成为水溶性荧光探针的应用潜力.     

荧光双重敏感响应型水溶聚合物的合成及其发光性能研究

将丙烯酰氯与荧光素反应,合成出丙烯酸酯单体3-丙烯酰氧基荧光素(Ac-Flu),然后采用自由基溶液聚合法将Ac-Flu与丙烯酰胺(AM)共聚,制备得到含有荧光素生色团的水溶性荧光共聚物poly(Ac-Flu-co-AM).合成单体Ac-Flu和共聚物poly(Ac-Flu-co-AM)采用核磁(NMR),质谱(HR-MS),红外光谱(FTIR),示差扫描量热法(DSC),可见紫外分光光度仪(UV-Vis)等方法进行了结构表征,同时采用荧光光谱对共聚物poly(Ac-Flu-co-AM)的荧光极其荧光对温度和pH敏感响应性进行了测定研究.结果表明,poly(Ac-Flu-co-AM)的水溶液和薄膜在520 nm附近均具有较强的荧光发射.其中,水溶液荧光强度在0～60℃范围内随着温度的升高呈线性下降,表现出较好的温度敏感响应性质.同时,水溶液荧光强度在pH=4～10范围内随着碱性的增强而升高,表现出较好的pH敏感响应性质.     

一种聚丙烯酸接枝型荧光纳米粒子的制备、性能及细胞成像

将N-氨基-4-N-甲基哌嗪-1,8-萘酰亚胺(AMN)通过酰胺化反应接枝到聚丙烯酸链上,利用生成的聚合物在水溶液中的自组装, 制备了一种水溶性荧光纳米粒子(PAAMN).采用紫外可见光谱、核磁共振氢谱、透射电镜、动态光散射和荧光光谱方法对PAAMN进行了表征,MTT法检测其细胞相容性,最后用荧光显微镜观察其自身荧光及细胞成像效果.实验结果表明, PAAMN为球状结构,萘酰亚胺荧光团的摩尔取代度为4.1%;在生理pH条件下,以390 nm为激发波长,PAAMN在534 nm处发射较强的荧光,且光稳定性较好;在pH 4.0~10.0范围内,其荧光波长无明显变化,荧光强度随pH值增大而逐渐减小,但pH敏感程度小于AMN.PAAMN具有良好的细胞相容性,能进入细胞,且在~390 nm激发光下发射绿色荧光,可用于细胞成像.     

丙三醇对水溶液中血红蛋白构象的影响——荧光猝灭和动态光散射研究

利用荧光猝灭法和动态光散射法测定丙三醇-水混合溶剂中血红蛋白(Hb)与联苯胺的结合距离和Hb的流体动力学半径, 并通过分析Hb荧光光谱和吸收光谱的变化, 探讨丙三醇与蛋白质分子在水溶液中相互作用的机理及其对蛋白质构象的影响. 结果表明, 丙三醇-水混合溶剂中Hb通过优先水化作用形成更紧密的构象, 溶剂体系的氢键形成能力下降对稳定蛋白质的构象有重要的影响, 丙三醇浓度较高的混合溶剂中氢键网络发生崩塌, 导致蛋白质构象产生进一步的折叠. 实验显示, 尽管Hb在丙三醇-水混合溶剂中保持较完整的血红素疏水空穴结构, 但是血红素疏水空穴以外肽段的构象发生显著变化, 并对血红蛋白的聚集状态造成一定的影响.     

利用荧光探针研究水溶性高分子溶液的结构

利用荧光探针技术研究水溶性高分子在溶液中的构象转变近年来引起了广泛的注意^[1-3]。这不仅是由于水溶性高聚物的实际应用日益增多,而且它还可能作为某种生化模拟体系,为研究了解复杂的生化体系提供有用资料。     

以萘酰亚胺衍生物基荧光高分子为载体和指示剂的 相分离免疫分析方法

以4-甲氧基-N-(2-N’,N’-二甲基氨基乙基-N’-烯丙基)萘二甲酰亚胺氯化铵(DMNAA)为荧光单体, 合成了一种pH敏感荧光高分子聚N-异丙基丙烯酰胺-4-甲氧基-N-(2-N’,N’-二甲基氨基乙基-N’-烯丙基)萘二甲酰亚胺氯化铵-N,N-二甲基氨丙基甲基丙烯酰胺[P(NIP-DMAPM-DMNAA)]. 采用共聚法将日本血吸虫抗原(SjAg)固定在P(NIP-DMAPM-DMNAA)上, 制备P(NIP-DMAPM-DMNAA)-SjAg连接物, 与日本血吸虫抗体(待测, SjAb)发生免疫反应后, 调节pH值, 使荧光高分子相变分离高分子-免疫组分连接物, 最后, 利用蛋白A对抗体的亲和性捕获P(NIP-DMAPM-DMNAA)-SjAg-SjAb, 通过测定高分子自身的荧光信号来定量 SjAb. 该新型高分子具有良好的荧光特性, 对pH响应快速, 37 ℃下相转变pH值为7.2, 分离免疫复合物时造成的损害低. 与传统相分离免疫分析比较, 新方法通过高分子相变分离和蛋白A捕获双重分离作用, 消除了非特异性组分和未反应的特异性免疫成分等的干扰; 利用高分子自身的荧光信号检测, 无须另外的标记物, 大大提高了免疫分析的简便性. 以日本血吸虫抗体为分析对象, 测得线性范围为1～1500 ng/mL, 抗体检出限为1.3 ng/mL, 相对标准偏差为3.6% (n＝10), 结果令人满意.     

Complexation between poly(acrylic acid) and poly(vinylpyrrolidone): Influence of the molecular weight of poly(acrylic acid) and small molecule salt on the complexation

Poly(acrylic acid) (PAA) with different molecular weight and poly(vinylpyrrolidone) (PVP) were prepared by free radical polymerization using 2,2′-azoisobutyronitrile (AIBN) as initiator in anhydrous methanol for PAA, and in distilled water for PVP. Then, the complexation between PAA and PVP in aqueous solution was studied by UV transmittance measurement and fluorescence probe technique. The result shows that (1) at low pH, the formation of complexation between PAA and PVP bases on the intermacromolecular hydrogen bond and the composition of the formed complex is around 3:2 (the unit molar ratio of PAA to PVP) at pH 2.60 over the range of pH investigated. (2) The cooperative interaction through the formation of hydrogen bond among active sites plays an important role in complex formation, and depends on the pH of solution, the required minimum chain length of poly(acrylic acid). (3) The hydrogen bond is not affected by small molecular salt, which only affects those carboxylic groups without forming hydrogen bond on the PAA chain.     

Enhancement of naringenin solution concentration by solid dispersion in cellulose derivative matrices

Naringenin (Nar) is an important bioactive flavonoid with poor organic solubility and oral bioavailability. It is highly promising for treatment of conditions including diabetes, hyperlipidemia, and hepatitis C infection. Amorphous solid dispersion (ASD) of Nar is an appealing way to enhance its solubility, and carboxylated cellulose esters are attractive polymers for this purpose because of their ability to stabilize drugs against crystallization in both solid and solution phases, while restricting drug release to the pH of the small intestine (ca. 6.8). We demonstrate that ASDs of Nar can be formed using such carboxylated cellulose derivatives as cellulose acetate adipate propionate (CAAdP), carboxymethylcellulose acetate butyrate (CMCAB) and hydroxypropylmethylcellulose acetate succinate (HPMCAS). We compare Nar solution concentrations and release profiles from these cellulosic ASDs to those from pure crystalline Nar, and to Nar ASD in poly(vinylpyrrolidinone) (PVP). We show that all polymers in this study form ASDs with Nar, that the PVP ASDs release Nar at both gastric (1.2) and small intestine (6.8) pH, and that the cellulosic polymers release Nar selectively at neutral pH. Solution concentrations of Nar are significantly enhanced from these ASDs. These preliminary studies indicate that HPMCAS, CAAdP, and CMCAB are practical ASD polymers for Nar due to their ability to generate and stabilize high solution concentrations, and their pH-triggered drug release.     

Separation of double-stranded DNA fragments by capillary electrophoresis in interpenetrating networks of polyacrylamide and polyvinylpyrrolidone

Mixtures of two polymers with totally different chemical structures, polyacrylamide and polyvinylpyrrolidone (PVP) have been successfully used for double-stranded DNA separation. By polymerization of acrylamide in a matrix of PVP solution, the incompatibility of these two polymers was suppressed. Laser light scattering (LLS) studies showed that highly entangled interpenetrating networks were formed in the solution. Further systematic investigation showed that double-stranded DNA separation was very good in these interpenetrating networks. With a concentration combination of as low as 2% w/v PVP (weight-average molecular mass Mr = 1 x 10(6) g/mol) + 1% w/v polyacrylamide (Mr = 4 x 10(5) g/mol), the 22 fragments in pBR322/HaeIII DNA, including the doublet of 123/124 bp, have been successfully separated within 6.5 min. Under the same separation conditions, similar resolution could only be achieved by using polyacrylamide (Mr = 4 x 10(5) g/mol) with concentrations higher than 6% w/v and could not be achieved by using only PVP (Mr = 1 x 10(6) g/mol) with a concentration as high as 15% w/v. It is noted that the interpenetrating network formed by 2% PVP and 1% polyacrylamide has a very low viscosity and can dynamically coat the inner wall of a fused-silica capillary. The separation reached an efficiency of more than 10(7) theoretical plate numbers/m and a reproducibility of less than 1% relative standard deviation of migration time in a total of seven runs. The interpenetrating network could stabilize polymer chain entanglements. Consequently, the separation speed was increased while retaining resolution.     

Self-assembly of multilayer films containing gold nanoparticles via hydrogen bonding

Polymer/Au nanoparticle multilayer ultrathin films are fabricated via hydrogen-bonding interaction by a layer-by-layer technique. The Au nanoparticles surface-modified with pyridine groups of poly(4-vinylpyridine) (PVP) are prepared in dimethyl formamide (DMF). Transmission electron microscopy (TEM) image shows that uniform nanoparticles are dispersed in the PVP chains. Poly(3-thiophene acetic acid) (PTAA) and poly(acrylic acid) (PAA) are utilized to form hydrogen bonds with PVP, respectively. Considering the pH-sensitive dissociation behavior of PTAA and PAA, we investigate the release behavior of the Au-containing multilayers at different pH values in this work. UV-vis spectroscopy and atomic force microscopy (AFM) are employed to monitor the buildup and the release of the multilayers. The results indicate that in the films assembled with gold nanoparticles, the polymers are difficult to be removed from the substrate. The interaction between the gold particles and the neighboring PVP chains is responsible for the phenomenon. Gold particles act as physical cross-link points in the multilayers. Due to the additional interaction caused by the gold nanoparticles in the films except the hydrogen-bonding interaction between PTAA (or PAA) and PVP, the stability of the Au-containing multilayer film is ensured even though the changes in pH values may result in the break of the hydrogen bonds.     

Interpolymer Complexes: Study of Interaction of Polyvinylpyrrolidone) with p-Hydrqxybenzoic Acid-Formaldehyde Copolymer in Nonaqueous Media

Interactions between poly(vinylpyrrolidone) (PVP) and p-hydroxyben-zoic acid-formaldehyde copolymer have been studied in methanol solution. The component polymers appear to form interpolymer complexes in distinct stages. The results are interpreted in terms of 1) hydrogen bonding, 2) ion-dipole interaction, 3) tacticity of PVP, and 4) multiple coordinating positions of component polymers.     

聚N-乙烯基吡咯烷酮对癸二酸-二苯并-18-冠-6共聚物薄膜性能的影响

分子量较高的癸二酸 二苯并 １８ 冠 ６共聚物可以制成具有一定韧性的薄膜,但该薄膜的透过性不好,当加入少量的水溶性聚合物聚乙烯吡咯烷酮（ＰＶＰ）后,薄膜的离子络合速度大幅度加快,并保持了对Ｋ＋较高选择性．同时研究了合金膜中ＰＶＰ的溶出量与温度及时间关系,以及合金膜的动态力学行为     

Electrolyte Effects on Charge Transport Behavior of [Os(bpy)2(PVP)10Cl]Cl and [Ru(bpy)2(PVP)10Cl]Cl Redox Polymers in Ultra‐Thin Films of Polyions

Metallopolymer films have important applications in electrochemical catalysis. The alternate electrostatic layer‐by‐layer method was used to assemble films of [Ru(bpy)₂(PVP)₁₀Cl]Cl (denoted as ClRu‐PVP) and [Os(bpy)₂(PVP)₁₀Cl]Cl (ClOs‐PVP) metallopolymers onto pyrolytic graphite electrodes. Film thickness estimated by quartz crystal microbalance was 6–8 nm. The effects of pH, electrolyte species and concentration on the electrochemical properties of these electroactive polymers were studied using cyclic voltammetry (CV). Behavior in various electrolytes was compared. Also the mass changes within the ultra‐thin film during redox of Os^2+/3+ were characterized by in situ electrochemical quartz crystal microbalance (EQCM). The results indicate rapid reversible electron transfer, and show that both ClRu‐PVP and ClOs‐PVP have compact surface structures while ClOs‐PVP is a little denser than ClRu‐PVP. Although hydrogen ions do not participate in the chemical reaction of either film, the movement of Na⁺ cation and water accompanies the redox process of ClOs‐PVP films.     

Synthesis of substituted poly(1-vinylpyrene)s and investigation of their fluorescent properties

A series of functionalized linear poly(1-vinylpyrene) (PVP) polymers bearing substituents such as ? NO₂, ? CHO, ? NH₂, ? Br, and ? CH?C(CN)₂, were prepared by chemical modification of PVP in solution. The degree of substitution in PVP? CH?C(CN)₂ was varied from 40% to nearly 100% by control of the reaction conditions. The other polymers were partially functionalized. The UV-visible and fluorescence spectroscopy of the polymers were studied in solution. The influence of solvent polarity, excitation energy, and degree of substitution on the fluorescence of the polymers were examined. © 1993 John Wiley & Sons, In     

芘荧光探针法研究海藻酸钠与SDS的作用

采用芘荧光法研究了海藻酸钠(NaAlg)与十二烷基硫酸钠(SDS)在不同pH水溶液中的相互作用.以芘单体的荧光光谱第一峰与第三峰的荧光强度之比(I1/I3)及激基缔合物与单体荧光强度之比(IE/IM)来探测芘分子所处环境的极性.结果表明:NaAlg水溶液随pH值降低,出现了聚合物的疏水微区;pH从7降到5,NaAlg类似简单盐,对SDS的临界胶束浓度(CMC)有明显的影响;在pH 3时,海藻酸主链上有足够的疏水片段,使得SDS与海藻酸通过疏水性作用而聚集.NaCl对NaAlg /SDS体系的影响亦较明显.     

Molecular modeling simulation and experimental measurements to characterize chitosan and poly(vinyl pyrrolidone) blend interactions

Blends of chitosan and poly(vinyl pyrrolidone) (PVP) have a high potential for use in various biomedical applications and in advanced drug‐delivery systems. Recently, the physical and chemical properties of these blends have been extensively characterized. However, the molecular interaction between these two polymers is not fully understood. In this study, the intermolecular interaction between chitosan and PVP was experimentally investigated using ¹³C cross‐polarization magic angle‐spinning nuclear magnetic resonance (¹³C CP/MAS NMR) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). According to these experimental results, the interaction between the polymers takes place through the carbonyl group of PVP and either the OH? C₆, OH? C₃, or NH? C₂ of chitosan. In an attempt to identify the interacting groups of these polymers, molecular modeling simulation was performed. Molecular simulation was able to clarify that the hydrogen atom of OH? C₆ of chitosan was the most favorable site to form hydrogen bonding with the oxygen atom of C?O of PVP, followed by that of OH? C₃, whereas that of NH? C₂ was the weakest proton donor group. The nitrogen atom of PVP was not involved in the intermolecular interaction between these polymers. Furthermore, the interactions between these polymers are higher when PVP concentrations are lower, and interactions decrease with increasing amounts of PVP. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1258–1264, 2008