PAMAM树状大分子负载和释放阿霉素的耗散粒子动力学模拟

采用耗散粒子动力学模拟方法研究了药物输送载体聚酰胺-胺(PAMAM)树状大分子对抗癌药物阿霉素(DOX)的负载和释放行为。构建了PAMAM树状大分子的粗粒化模型,该模型能准确地重现树状大分子的构象性质。考察了PAMAM树状大分子代数(G)对DOX负载以及pH环境对DOX释放的影响。模拟结果表明,PAMAM树状大分子主要通过疏水作用将DOX包封于内部空腔,G6和G7 PAMAM树状大分子的负载能力较强,因为其孔隙率较高,内部有更多的疏水空腔。在低pH环境下,PAMAM树状大分子结构发生变化,DOX分子能快速地从其中释放,主要原因是PAMAM的伯胺、叔胺和DOX伯胺发生质子化,质子化基团间的静电排斥作用使得PAMAM树状大分子发生溶胀,导致其内部空腔暴露,促进了DOX的释放。本工作可以为基于树状大分子的药物输送体系的设计和优化提供参考。     

PAMAM树状大分子的合成及除油性能研究

通过发散法合成了各代聚酰胺-胺(PAMAM)树状大分子,整代PAMAM树状大分子合成的最适宜条件为:反应时间24 h,反应温度25℃,n(0.5代PAMAM树状大分子):n(乙二胺)=1:8,溶剂甲醇占总溶液质量分数的20%.用红外光谱对各代产品进行表征,结果证明合成产物是目标分子结构.处理胜利油田孤岛四号联合站污水实验表明,合成的3.0代PAMAM树状大分子除油效果最佳,除油效果好于现场使用的进口药剂罗曼哈斯,在加剂量为70 mg/L时,含油从888.7 mg/L降到132.5 mg/L,除油率可达到85.1%,悬浮物从138 mg/L降到73 mg/L.     

树状大分子的手性构建

综述了手性基团的树状大分子中的构建,并对此类化合物的性质及研究和应用前景作了简要介绍。     

PAMAM树状大分子在水处理中的应用研究进展

PAMAM树状大分子具有特殊结构与性能,应用于水处理中,具有无毒和高效的特点。本文综述了PAMAM树状大分子在含重金属离子废水、染料废水、高硅水等水处理中的应用研究。PAMAM树状大分子在水处理中的处理效果受溶液的pH值、作用时间、树状大分子的代数等因素的影响,且在含重金属离子废水处理中可再生。最后探讨了PAMAM树状大分子在水处理应用中存在的问题,预测未来将通过改性PAMAM树状大分子或合成新树状大分子扩大其在水处理中的应用范围。     

重质油稳定性的耗散粒子动力学模拟

重质油的稳定性关乎其开采、储运及加工过程安全。准确的重质油稳定性判定方法对重质油生产及加工过程具有重要指导意义,然而重质油稳定性的经验判定法存在一定的局限性。从理论层面建立重质油稳定性的判定方法将提高重质油稳定性的预测准确度,本文基于耗散粒子动力学方法（DPD）模拟了不同重质油体系分子的微观聚集态。模拟结果表明,重质油体系的沥青质聚集率与胶体不稳定指数（C.I.I.）及稳定性判定图的判定结果吻合,验证了模拟体系的准确性。在此基础上,基于DPD模拟结果对C.I.I.及稳定性判定图的局限性进行了讨论,提出了改进的稳定性判定图用于重油稳定的快速判定。提出的重质油稳定性判定方法有望用于实际工业过程。     

重质油稳定性的耗散粒子动力学模拟

重质油的稳定性关乎其开采、储运及加工过程安全。准确的重质油稳定性判定方法对重质油生产及加工过程具有重要指导意义,然而重质油稳定性的经验判定法存在一定的局限性。从理论层面建立重质油稳定性的判定方法将提高重质油稳定性的预测准确度,本文基于耗散粒子动力学方法（DPD）模拟了不同重质油体系分子的微观聚集态。模拟结果表明,重质油体系的沥青质聚集率与胶体不稳定指数（C.I.I.）及稳定性判定图的判定结果吻合,验证了模拟体系的准确性。在此基础上,基于DPD模拟结果对C.I.I.及稳定性判定图的局限性进行了讨论,提出了改进的稳定性判定图用于重油稳定的快速判定。提出的重质油稳定性判定方法有望用于实际工业过程。     

树状大分子封装金属纳米粒子的催化作用

树状大分子封装金属纳米粒子是一种新型的有机 /无机杂化纳米材料 ,由树状大分子内螯合金属离子通过还原产生相应的零价金属纳米粒子的方法制备。综述了树状大分子封装金属纳米粒子的催化作用及研究进展 ,讨论了在水、有机溶剂、氟 /有机两相溶剂和超临界CO2 中 ,树状大分子封装催化剂 (DECs)对氢化反应和碳 碳偶合反应的催化作用。最后对树状大分子封装金属纳米粒子的应用进行了展望。     

树状大分子金属催化剂的研究进展

树状大分子模板金属催化剂是一种新型的均相、择型催化剂,综述了数年来以树枝状大分子为模板的各种金属催化剂的合成、表征及应用等方面的研究进展,介绍了催化剂的回收再利用方法,并对未来发展方向进行了展望。     

聚酰胺胺(PAMAM)树状大分子在涂料中的应用研究

介绍了聚酰胺胺（PAMAM）树状分子的独特结构和性能，综述了聚酰胺胺树状分子在涂料中的应用研究。     

PAMAM树状大分子与Ag~+配位的紫外光谱研究

利用紫外可见分光光度法研究了以三(2-氨基乙基)胺为核的PAMAM树状大分子与Ag+的配位作用,探讨了Ag+与PAMAM的物质的量比、溶液的pH值以及相互作用时间对配位的影响。结果表明,随着Ag+与PAMAM的物质的量比的增加,配位的Ag+数目增加,吸收强度增加,且最大吸收波长红移;溶液pH值对配位体系影响显著,在酸性条件下,PAMAM的伯胺和叔胺会被质子化,H+取代Ag+,这为PAMAM的循环利用提供了可靠的理论依据;另外,反应时间和温度对配位体系也有一定的影响,延长反应时间和升高反应温度,均会使吸光强度增加。     

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。     

Dendrimers as drug delivery vehicles: non‐covalent interactions of bioactive compounds with dendrimers

This mini review highlights issues associated with the use of dendrimers as drug delivery vehicles. The review introduces dendrimers and summarizes findings on their use in vivo and in vitro. Specifically, this review is limited to examples wherein the drug is non‐covalently associated with the dendrimer. Examples wherein the drug is covalently attached to the dendrimer are not discussed. Copyright © 2007 Society of Chemical Industry     

聚乳酸载药微球形成机理的模拟分析与实验研究

对聚乳酸载药微球的形成过程进行了耗散颗粒动力学模拟和实验研究。载药体系以硝苯地平为模型药物、聚乳酸（poly-lactic acid, PLA）为载体材料、聚乙烯醇（poly vinyl alcohol, PVA）为稳定剂。通过研究,提出了聚乳酸载药微球的形成机理,认为微球形成过程可分为4个阶段,即高度分散阶段、PLA分子聚集阶段、硝苯地平分子向微球内部扩散阶段和微球的形成及稳定阶段。机理分析和模拟表明,微球对硝苯地平的包载量有一个临界值,硝苯地平浓度低于该值,几乎所有的硝苯地平分子都能扩散进微球的内部;高于该值,则部分硝苯地平分子难以扩散进微球内部,而分散在介质中,形成硝苯地平聚集体。     

Preparation and characterization of PVA films with magnetic nanoparticles: The effect of particle loading on drug release behavior

This article deals with the drug release behavior of theophylline (Th) from poly(vinyl alcohol) (PVA) hydrogels, prepared with magnetic nanoparticles at different particle loadings. These biocompatible matrices were obtained by incorporating different amounts of an aqueous ferrofluid into PVA hydrogels, loaded with Th as a marker for drug‐delivery studies. PVA films with magnetic particles proved to be magnetic field‐responsive materials as the drug release decreased through the application of a relative low and uniform magnetic field for particle concentrations of 0.9% w/w or higher. Moreover, the percentage of restriction of drug release is found to be correlated with particle loading. The in vitro release profiles were analyzed by applying a semiempirical power law to obtain the kinetic parameters. The value of the release exponent was found to be in the range 0.54–0.56 in all experiments, which thus indicates a predominant diffusional mechanism for drug release from these smart magnetic hydrogels. This effect suggests the possibility of modulating the release behavior by controlling the particle content in the preparation of the composites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Antitumor efficacy of doxorubicin encapsulated within PEGylated poly(amidoamine) dendrimers

We report here a general approach to using poly(amidoamine) (PAMAM) dendrimers modified with polyethylene glycol (PEG) as a platform to encapsulate an anticancer drug doxorubicin (DOX) for in vitro cancer therapy applications. In this approach, PEGylated PAMAM dendrimers were synthesized by conjugating monomethoxypolyethylene glycol with carboxylic acid end group (mPEG‐COOH) onto the surface of generation 5 amine‐terminated PAMAM dendrimer (G5.NH₂), followed by acetylation of the remaining dendrimer terminal amines. By varying the molar ratios of mPEG‐COOH/G5.NH₂, G5.NHAc‐mPEG_n (n = 5, 10, 20, and 40, respectively) with different PEGylation degrees were obtained. We show that the PEGylated dendrimers are able to encapsulate DOX with approximately similar loading capacity regardless of the PEGylation degree. The formed dendrimer/DOX complexes are water soluble and stable. In vitro release studies show that DOX complexed with the PEGylated dendrimers can be released in a sustained manner. Further cell viability assay in conjunction with cell morphology observation demonstrates that the G5.NHAc‐mPEG_n/DOX complexes display effective antitumor activity, and the DOX molecules encapsulated within complexes can be internalized into the cell nucleus, similar to the free DOX drug. Findings from this study suggest that PEGylated dendrimers may be used as a general drug carrier to encapsulate various hydrophobic drugs for different therapeutic applications. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40358.     

Synthesis of chitosan‐graft‐β‐cyclodextrin for improving the loading and release of doxorubicin in the nanopaticles

Chitosan‐graft‐β‐cyclodextrin (CS‐g‐β‐CD) copolymer was synthesized by conjugating β‐cyclodextrins to chitosan molecules through click chemistry. The copolymer structure was characterized by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR). CS‐g‐β‐CD/CMC nanoparticles were prepared by a polyelectrolyte complexation process in aqueous solution between CS‐g‐β‐CD copolymer and carboxymethyl chitosan (CMC), which was used to load anticancer drug (Doxorubicin hydrochloride, DOX·HCl) with hydrophobic group. The particle size, surface charge, zeta potential, and morphology of the nanoparticles were characterized with dynamic light scattering. The drug loading efficiency and in vitro release of DOX·HCl of the nanoparticles were measured by ultraviolet spectrophotometer. The results demonstrated that the size, surface charge and drug loading efficiency of the nanoparticles could be modulated by the fabrication conditions. The drug loading efficiency of CS‐g‐β‐CD/CMC nanoparticles was improved from 52.7% to 88.1% because of the presence of β‐CD moieties with hydrophobic cavities, which can form inclusion complexes with the drug molecules. The in vitro release results showed that the CS‐g‐β‐CD/CMC nanoparticles released DOX·HCl in a controlled manner, importantly overcoming the initial burst effect. These nanoparticles possess much potential to be developed as anticancer drug delivery systems, especially those drugs with hydrophobic group. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41034.     

Electrospray preparation of propranolol‐loaded alginate beads: Effect of matrix reinforcement on loading and release profile

In the present study, propranolol loaded‐calcium alginate beads were prepared from concentrated solutions of sodium alginate, using combined method of electrospray and ionotropic gelation. The objectives of the study were to increase the propranolol‐HCl loading and to decrease its initial burst release. However, the effects of voltage, nozzle diameter, flow rate, and concentration of sodium alginate on size of the beads and drug entrapment efficiency (DEE) were also investigated. The matrix of alginate beads was reinforced with dextran sulfate and/or coated with chitosan. The mean particle size of the beads, their swelling behavior, and drug entrapment efficiency were characterized. Furthermore, the drug release profiles from the prepared beads in simulated gastric fluid and intestinal fluid were evaluated and compared. Among the parameters that affected the electrospray of alginate, voltage had a pronounced effect on the size of beads. The size of beads was reduced to a minimum value on increasing the voltage. Furthermore, increasing the flow rate, alginate concentration, and nozzle diameter and decreasing the voltage led to improvement in DEE. Enhancing the alginate concentration as well as coating with chitosan and reinforcing with dextran sulfate led to increase of the encapsulation efficiency and therefore decrease of the drug release rate in both pHs. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41334.