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.     

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。     

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。     

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。     

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。     

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。     

Physicochemical properties of acylated low molecular weight chitosans

Hydrophobically modified chitosans are developing progressively in drug delivery system due to their ability to encapsulate drugs with the amphiphilic architecture. In this study, low molecular weight chitosans were acylated with hexanoyl (LCh-C6), octanoyl (LCh-C8) and decanoyl (LCh-C10) groups to study their physicochemical properties for the potential as drug carriers. Both fourier transform-infrared (FT-IR) and ¹H NMR (Nuclear Magnetic Resonance) analyses confirmed the successful acylation of alkyl chains onto chitosan backbone. LCh-C6, LCh-C8 and LCh-C10 showed the similar value of critical aggregation concentration around 40?µg?L^?1. The average particle size of LCh-C6, LCh-C8 and LCh-C10 obtained by dynamic light scattering measurement was compared to by mean of transmission electron microscopy. Acylated low molecular weight chitosans (LChA) showed higher encapsulation efficiency and drug loading toward hydrophobic salicylic acid as compared to hydrophilic caffeine, as well as exhibited higher increment in particle size due to possible inner volume expansion. Both long alkyl chains and high degree of substitution contributed to better drug encapsulation of LChA.     

Synthesis of supramolecular biodendrimeric β-CD-(spacer-β-CD)21 via click reaction and evaluation of its application as anticancer drug delivery agent

The per-β-CD dendrimer (10), having 21 β-CD residues connected to the core β-CD in the primary and secondary sides with encapsulation efficacy and β-CDs moiety to preserve the biocompatibility properties was synthesized using click reaction. The dendritic network and β-CD cavity of the obtained dendrimer were utilized to form a supramolecular compound via the formation of a host-guest inclusion complex with methotrexate (MTX) drug molecule. The MTT assay of compound 10 showed very low toxicity on T47D cancer cells. In vitro drug release investigation at pHs 7.4, 5, and 3 indicated that the release manner was remarkably pH dependent.     

Influence of Anionic Surface Charged Biocompatible Dendrimer With a Photosensitizer,Protoporphyrin IX,on Human Red Blood Cells: A Spectroscopic Investigation

A biocompatible anionic dendrimer with carboxylic acid and phenolic hydroxyl functional groups at the surface of every half and full generations was designed by condensing phloroglucinol and succinic acid and its hemolytic effect on red blood cells was studied. The study reveals that the anionic surface charged dendrimer exhibits hemocompatibility and satisfies the reduction of dark toxicity of photosensitizer when loaded inside the nanocarrier, one of the prime requirements for a drug delivery system in photodynamic therapy applications.     

A mesoscale model for diffusion and permeation of shale gas at geological depth

The demand on energy is rising and shale gas as an important unconventional energy resource has received worldwide attention. It has shown a significant effect on the world's energy structure after the commercial exploitation of shale gas in the United States. Understanding diffusion and permeation of shale gas at geological depths is quite essential, but it cannot be described by traditional Fick or Knudsen diffusion models. In this work, we use dual control volume–grand canonical molecular dynamics method to systematically investigate the permeation process of shale gas in montmorillonite (i.e., a clay mineral of shale) at different geological depths. Results indicate that temperature, pressure, and pore size have an important effect on the permeability, and Knudsen equation cannot describe the permeability of shale gas. Accordingly, on the basis of these simulated data, we propose a new mesoscale model to describe the permeability of shale gas at geological depths. The new mesoscale model shows extensive applicability and can excellently reproduce the extrapolation testing data, and it satisfactorily bridges the gap between Knudsen diffusion and Fick diffusion, which provides important fundamentals for exploitation of shale gas. © 2017 American Institute of Chemical Engineers AIChE J, 64: 1059–1066, 2018