树枝状大分子聚酰胺-胺的合成与性能

采用发散合成法合成了以乙二胺为核的1.0～3.0代的系列树枝状高分子聚酰胺 胺(PAMAM).采用IR、核磁共振、端基分析对PAMAM的结构进行了表征,考察了PAMAM水溶液的表面活性及其对难溶药物水杨酸的增溶能力.结果表明:半代PAMAM具有一定的表面活性,整代PAMAM几乎没有表面活性,表面活性主要与PA MAM的端基结构有关;PAMAM对难溶药物水杨酸具有增溶作用,增溶能力随代数和质量浓度的增加而增大,增溶方式与传统的表面活性剂不同.     

PAMAM树状大分子对酮基布洛芬溶解度的影响

以酮洛芬为模型药物,研究聚酰胺-胺(PAMAM)树状大分子对酮洛芬的增溶作用,并探讨其作用机理.采用紫外光谱法测定了G1.0、G1.5、G2.0、G2.5、G3.0、G3.5PAMAM在不同浓度和不同pH时对酮洛芬的增溶量.并运用计算机模拟方法对PAMAM与酮洛芬相互作用的机理进行了探讨.实验结果表明,酮洛芬的溶解度随溶液pH值变化而变化,在pH4.0～6.0范围内,PAMAM树状大分子对酮洛芬的增溶量随着PAMAM的代数、浓度和溶液pH的增加而增大.整代和半代都具有增溶作用.然而,在同一pH条件下,对于具有相同官能团数目的整代和半代,整代增溶效果要高于半代.计算机模拟结果表明PAMAM与酮洛芬主要靠静电作用力结合.增溶机理可能是酮洛芬的羧基与PAMAM的伯胺和叔胺发生静电作用.     

Pluronic嵌段共聚物F127胶团对布洛芬的增溶(英文)

研究了PluronicF127胶团溶液对药物布洛芬(IBU)的增溶作用.通过芘探针荧光法测定了不同温度下F127在水溶液和0.01mo·lL-1pH7.4磷酸盐缓冲生理(PBS)溶液中的临界胶束浓度(cmc),采用高效液相色谱(HPLC)测定了F127溶液中布洛芬的溶解度,并依据公式计算了增溶参数(摩尔增溶量c和胶团-水分配系数K),考察了温度、溶剂和F68的加入对F127胶团化行为及其对布洛芬增溶作用的影响.结果表明:布洛芬的溶解度随F127质量分数的提高线性增加;随着温度升高,cmc急剧下降,胶团内核的疏水性增强,χ和K稍有增大;与水溶液相比,在PBS溶液中cmc减小,χ几乎不变,K显著降低;F68的加入对F127胶团的性质几乎无影响,对增溶的影响也不明显.对增溶参数的分析表明,K反映的是药物布洛芬的性质,χ则可反映嵌段共聚物F127的溶解效能,并证实了布洛芬是通过F127胶团的内核和栅栏层而实现增溶的.     

以乙二胺为核心的聚酰胺-胺树形高分子的合成及毛细管电泳分离研究

在-30℃下合成了1．0G～6.0G聚酰胺．胺(PAMAM)树形高分子,并采用核磁共振、元素分析对其进行了表征;采用毛细管电泳对1．0GPAMAM进行了分离。结果表明：在该温度下合成的PAMAM具有较好的结构完整性,而毛细管电泳是一种有效的分离提纯PAMAM树形高分子的方法。     

树枝状大分子PAMAM合成及对蒙脱土插层改性和应用研究

有机阳离子改性蒙脱土已广泛应用于聚合物改性制备高性能聚合物。本文合成了不同代数G0(零代)、G2(二代)的树枝状大分子聚酰胺-胺(PAMAM),同时对G0、G2代PAMAM进行了季铵化改性,得到了PAMAM季铵盐,进一步用PAMAM季铵盐插层改性钠基蒙脱土(Na+-MMT)得到了PAMAM季铵盐改性蒙脱土(PAMAM/MMT)。XRD分析表明,PAMAM季铵盐己与Na+-MMT中的Na+进行了离子交换,同时提出了G0、G2代PAMAM季铵盐对MMT的双分子和单分子插层模型。进一步研究了PAMAM/MMT对聚碳酸酯(PC)的流变性能的影响规律,结果表明PAMAM/MMT可明显降低聚碳酸酯熔融剪切粘度,有利于提高其加工性能。     

聚酰胺―胺的合成表征及对铝酸钠溶液物化性质的影响

用发散法合成以乙二胺为核的聚酰胺―胺(PAMAM 0.5～6.0代),采用元素分析、电位滴定等方法对合成产物进行表征分析,考察了不同分子代数、不同浓度的PAMAM对铝酸钠溶液表面张力和电导率等物理化学性质的影响。结果表明,该条件下合成的PAMAM具有较好的结构完整性。此外随着添加剂PAMAM的增加,铝酸钠溶液的表面张力急剧降低,半代数的PAMAM具有较好的表面活性,有望成为新一代的表面活性剂;整代数的PAMAM也有一定的表面活性。PAMAM属于非离子型表面活性剂,因此随着PAMAM的加入,铝酸钠溶液的电导率改变不大。     

PAMAM分子与 Cr3+离子配位作用的研究

利用外向分散合成法合成了以乙二胺为核的聚酰胺-胺(PAMAM)树枝形分子,并用分光光度法研究了不同代数的PAMAM分子与Cr^3 的配位作用。实验结果表明PAMAM分子的代数、浓度以及水溶液的pH值对配位作用有显著的影响。随着PAMAM分子代数的增加,其与Cr^3 的最大配位数不断增加,得出的结果和理论值接近。     

脂肪酸十二烷基铵在四氯化碳中的聚集行为

通过碘光谱法和对水的增溶研究了乙酸十二烷基铵(DAA)、丙酸十二烷基铵(DAP)和丁酸十二烷基铵(DAB)在四氯化碳中的聚集作用; 碘光谱测得的(cmc)~I约比水增溶法测得的(cmc)~W低一个数量级。可能因为碘光谱法测得的是开始发生聚集时的cmc, 这时聚集体较小, 对水无增溶能力; 只有当聚集体随浓度升高而长大到一定程度时, 才能开始增溶水。实验表明, DAA, DAP和DAB的反胶束对水的饱和增溶能力, 分别相当于每一个表面活性分子增溶4.2, 9.4和13.5个水分子。根据球型反胶束模型, 计算了反胶束聚集数、捕集水团的半径和自由水团的半径。     

聚酰胺-胺树形分子荧光性能研究及其在指纹识别领域应用初探

研究了不同温度、浓度、pH值条件下,不同代数、不同端基类型(酯端基和胺端基)的PAMAM(聚酰胺-胺)树形分子的强荧光发射性能.PAMAM树形分子发射强荧光是沿树形结构方向的酰胺基团中的n→π*跃迁和其密实的球状结构共同作用的结果.树形分子的荧光强度在低pH值或者低温条件下大幅度提高,并且在稀溶液中与浓度成线性关系,在高浓度或者高代数条件下逐渐偏离线性关系.本文还对上述规律的内在机理进行了研究:第一,低pH值条件下,PAMAM树形分子内的叔胺基被氢离子质子化,酰胺荧光发射中心和叔胺基团之间的光诱导电子转移作用被抑制,甚至中断,因此荧光强度急剧升高;第二,随着温度升高,PAMAM树形分子的去活作用增强,荧光强度降低;第三,浓度超过临界点浓度后,由于浓度消光作用,PAMAM树形分子的荧光强度不再随浓度增加而线性增强.最后,将PAMAM树形分子水溶液用于锡纸上油印潜指纹的识别,经处理后的指纹在365 nm紫外光的激发下发射出蓝色荧光,潜指纹被成功地清晰识别.     

脂肪醇和电解质对丙酸十二铵盐在四氯化碳中增溶水的影响

研究了己醇，辛醇、Ｋｕｉ醇和月桂醇对丙酸十二铵（ＤＡＰ）－四氯化碳反胶束溶液增溶水和氯化钠水溶液的影响，在ＤＡＰ浓度固定时，水增溶量对醇浓度的关系出现极大值，在醇浓度相同时，长碳链醇较短碳链醇有更大的增溶水能力，在固定ＤＡＰ浓度和增溶水量最大时，氯化钠的存在将导致水溶液增溶量的显著下降，乙酸十二铵（ＤＡＡ）、ＤＡＰ和丁酸十二铵（ＤＡＢ ）的四氯化碳溶液对氯化钠水溶液的增溶量随氯化钠浓度的升高而有不     

PAMAM树形分子与Cd2＋的配位作用研究及CdS/PAMAM纳米复合材料的制备与表征

CdS半导体纳米簇具有独特的光、电性能, 如何制备均匀分散的、能够稳定存在的CdS纳米簇是目前的研究热点之一. 以聚酰胺-胺(PAMAM)树形分子为模板, 原位合成了CdS纳米簇. 首先用UV-Vis分光光度法研究了与树形分子的配位机理, 得出G4.5和G5.0的平均饱和配位数分别为16和34, 并发现在G4.5PAMAM树形分子中Cd^2＋主要与最外层叔胺基配位, 在G5.0PAMAM树形分子中Cd^2＋主要与最外层伯胺基配位. 酯端基的G4.5的模板作用要明显优于胺端基的G5.0. 通过改变Cd^2＋与G4.5树形分子的摩尔比可以得到不同粒径的CdS纳米簇. 溶液的pH值对CdS纳米簇影响很大, pH在7.0左右制备的CdS纳米簇粒径小而均匀, 且溶液稳定性高. 用UV-Vis分光光度计和TEM对CdS纳米簇的大小和形貌进行了表征. 结果表明TEM观测CdS纳米簇的粒径要大于用Brus公式的估算值.     

Low generational polyamidoamine dendrimers to enhance the solubility of folic acid:A‘‘dendritic effect’’investigation

Low generational(G0–G2,G for generation) polyamidoamine(PAMAM) dendrimers were investigated as enhancers to improve the aqueous solubility of folic acid at pH 11 and pH 5.In these two cases,the solubility of folic acid increases with both the dendrimer concentration and generation.However,the solubilization mechanism is different.The electrostatic interaction between the primary amines of dendrimers and the ionized carboxylic groups of folic acid dominates the dissolution process at pH 11 while the increase of the solubility of folic acid at pH 5 is attributed to the hydrophobic encapsulation inside the dendrimer molecules.In addition,for comparison ethylenediamine was used as a small molecule control to examine the ‘‘dendritic effect' in the dendrimer-related solubilization process.Interestingly,PAMAM dendrimers exhibit,at pH 5,a significant superiority over ethylenediamine in enhancing solubility,whereas this ‘‘dendritic effect' cannot be observed under the basic condition.     

Nanoscale protein pores modified with PAMAM dendrimers

We describe nanoscale protein pores modified with a single hyperbranched dendrimer molecule inside the channel lumen. Sulfhydryl-reactive polyamido amine (PAMAM) dendrimers of generations 2, 3 and 5 were synthesized, chemically characterized, and reacted with engineered cysteine residues in the transmembrane pore alpha-hemolysin. Successful coupling was monitored using an electrophoretic mobility shift assay. The results indicate that G2 and G3 but not G5 dendrimers permeated through the 2.9 nm cis entrance to couple inside the pore. The defined molecular weight cutoff for the passage of hyperbranched PAMAM polymers is in contrast to the less restricted accessibility of flexible linear poly(ethylene glycol) polymers of comparable hydrodynamic volume. Their higher compactness makes sulfhydryl-reactive PAMAM dendrimers promising research reagents to probe the structure of porous membrane proteins with wide internal diameters. The conductance properties of PAMAM-modified proteins pores were characterized with single-channel current recordings. A G3 dendrimer molecule in the channel lumen reduced the ionic current by 45%, indicating that the hyperbranched and positively charged polymer blocked the passage of ions through the pore. In line with expectations, a smaller and less dense G2 dendrimer led to a less pronounced current reduction of 25%. Comparisons to recordings of PEG-modified pores revealed striking dissimilarities, suggesting that differences in the structural dynamics of flexible linear polymers vs compact dendrimers can be observed at the single-molecule level. Current recordings also revealed that dendrimers functioned as ion-selectivity filters and molecular sieves for the controlled passage of molecules. The alteration of pore properties with charged and hyperbranched dendrimers is a new approach and might be extended to inorganic nanopores with applications in sensing and separation technology.     

以聚酰胺-胺树形分子为模板制备AgI纳米簇

本文以聚酰胺-胺(PAMAM)树形分子为模板,原位制备AgI纳米簇.系统地研究了AgI纳米簇制备过程中各种反应条件如树形分子端基、反应时间、Ag+与PAMAM摩尔比等对AgI纳米簇粒径的影响,分别用紫外-可见光谱、荧光光谱、透射电镜等对所制备的纳米簇进行表征.在相同的条件下,以G4.5-COOH3为模板较以G5.0-NH2为模板制备的AgI纳米簇粒径小、分布均匀,这主要取决于G4.5-COOCH3PAMAM树形分子所起的“内模板”作用.G4·5-COOH3树形分子浓度为1×10-5mol/L,Ag+与树形分子摩尔比为30∶1时所制备的AgI纳米簇的粒径分布均匀、稳定性好,室温避光可稳定存在两个月以上.     

Direct force measurements between adlayers consisting of poly(amidoamine) dendrimers with primary amino groups or quaternary ammonium groups

Adsorption of poly(amidoamine) generation 3 (PAMAM G3) dendrimer with surface amino groups or PAMAM G0 dendrimer with quaternary ammonium groups (C8qbG0) onto glass has been studied by colloidal probe atomic force microscopy. The adlayer-adlayer interactions for these adsorbates are quite different despite the fact that they are almost equal in the hydrodynamic radius. In aqueous PAMAM G3 dendrimer solutions the electrostatic repulsion is predominant. The conformation of the adsorbed layer is flat and the protrusion of the individual dendrimers is negligible. On the other hand, C8qbG0 behaves as a surfactant and the layered structure of C8qbG0 is expected to be a patchy bilayer. Dispersion stability of silica suspensions with the adsorption of these dendrimers can be correlated with the force data obtained.     

Thermosensitive properties of poly(amidoamine) dendrimers with peripheral phenylalanine residues

Dendrimers are unique polymers with globular shapes and well-defined structures. We previously prepared poly(amidoamine) (PAMAM) dendrimers having phenylalanine (Phe) residues at every chain end of the dendrimer as efficient gene carriers. In this study, we found that Phe-derivatized PAMAM dendrimers change their water solubility depending on temperature. The dendrimers were soluble in aqueous solutions at low temperatures, but they became water-insoluble at temperatures above a specific threshold, which is termed the lower critical solution temperature (LCST). Although the LCST of Phe-modified dendrimers decreased with increasing dendrimer generation, these dendrimers exhibited an LCST of 20-30 degrees C under physiological conditions. In addition, the LCST of the dendrimers was controlled by introducing isoleucine (Ile) residues at chain ends of dendrimers at varying ratios with respect to Phe residues. The PAMAM dendrimers are known to encapsulate various drug molecules. For these reasons, temperature-sensitive dendrimers might be useful as efficient drug carriers with controlled size and temperature-responsive properties.     

Morphological change of gold-dendrimer nanocomposites by laser irradiation

Gold-dendrimer nanocomposites are prepared in aqueous solutions in the presence of poly(amidoamine)dendrimers (PAMAM) (generation 3 and 5) or poly(propyleneimine)dendrimers (PPI) (generation 3 and 4) by wet chemical NaBH(4) method. Thus prepared gold-dendrimer nanocomposites are irradiated by laser at 532 nm. UV-vis absorption spectroscopy and transmission electron microscopy reveal that the gold nanoparticles grow with the laser irradiation time as well as the fluence of the laser; in particular, the gold nanoparticles prepared at lower concentrations of PAMAM dendrimer as well as lower generations of PAMAM grow significantly. On the other hand, in the case of PPI dendrimers, the gold nanoparticles hardly grow by irradiation. In addition, dynamic light-scattering measurements show that the laser irradiation markedly promotes the association of the gold-PAMAM G3 dendrimer nanocomposites compared to that of the gold-PAMAM G5 dendrimer nanocomposites, while the sizes of association for the gold-PPI G3, G4 dendrimer nanocomposites hardly change by laser irradiation.     

聚酰胺-胺型树枝状高分子水溶液的表面活性

树枝状化合物是一类三维的、高度有序的新型高分子．与传统高分子相比,这类化合物在合成时,可以在分子水平上严格控制,设计分子大小、形状、结构和功能基团,产物一般高度对称,单分散性好．因而具有广泛的潜在用途［１,２］．近年来,已引起广大化学工作者的重视．但...     

Synthesis of conjugates of β-cyclodextrin with polyamidoamine dendrimers and their molecular inclusion interaction with levofloxacin lactate

Polyamidoamine (PAMAM) dendrimers of different generations (G2 and G4) conjugated with β-cyclodextrin (β-CD), PAMAM (G2, G4)-CD, were synthesized using substitution reaction from mono-6-iodine-β-cyclodextrin and PAMAM dendrimers. The resulting molecular structures were characterized by NMR, IR. The molecular interaction between various dendrimers and levofloxacin lactate (LFL) were investigated by monitoring the fluorescence of LFL in the presence of dendrimers in buffer solution (pH 7.4) at 25?°C. It was found that the PAMAM (G2, G4)-CD possesses higher sensitizing ability than that of the corresponding parent dendrimers and natural β-CD, and increases concomitantly with the increases of generation and content of β-CD, suggesting that the PAMAM (G2, G4)-CD possesses stronger inclusion ability with LFL. The possible interaction mechanism between PAMAM-CD and LFL was proposed by ¹H NMR analysis and theoretical calculation. The results show that the LFL molecule is located at the amine end of dendrimer molecule and along the side of cyclodextrin cavities to form supramolecular complexes. Furthermore, results indicate that the main driving force of the complex could be attributed to the electrostatic interactions and hydrogen bonding between LFL and PAMAM-CD, as well as the synergistic effect of intermolecular forces.     

环糊精修饰聚酰胺-胺树状高分子的合成及其与乳酸左氧氟沙星的作用研究

合成了一系列以环糊精修饰的树状高分子化合物PAMAM(G2,G4)-β-CD,用IR,1H-NMR等手段表征了其结构,并采用荧光光谱法对其在缓冲溶液中与乳酸左氧氟沙星(LFL)的相互作用进行了研究.结果表明,经环糊精修饰树状高分子的增敏率远大于未修饰的和天然环糊精,且随代数和环糊精含量的增加而增大,表明其具有强于相同代数PAMAM的分子键合能力,这些强的键合能力源于环糊精修饰树状高分子化合物中两种结构单元的疏水作用、静电作用和氢键作用的协同效应.