以酯端基PAMAM树形分子为模板在N,N-二甲基甲酰胺溶剂中制备金纳米粒子

用UV-vis、FT-IR光谱研究了HAuCl4和酯端基聚酰胺胺(PAMAM)树形分子在N,N-二甲基甲酰胺(DMF)溶剂中的相互作用,提出HAuCl4与树形分子之间的络合机理:[AuCl4]-离子与质子化叔胺基团形成离子对,Au3 离子与PAMAM树形分子上的酯基和酰胺基团形成配位作用.在DMF溶剂中酯端基PAMAM树形分子与HAuCl4配位后用柠檬酸钠还原形成金纳米粒子,UV-vis光谱和TEM图像分析表明了随树形分子代数的增加,金纳米粒子的直径减小,并提出了树形分子-金纳米复合物的结构模型:(1)较低代数的树形分子环绕在金粒子的外围;(2)在较高代数的树形分子空腔内部封装金纳米粒子.     

以树形分子为模板制备金纳米簇及其表征

利用酯端基聚酰胺-胺（PAMAM）树形分子为模板,以N,N-二甲基甲酰胺（DMF）为溶剂,用硼氢化钠还原氯化金制备了树形分子封装的金纳米簇复合物.UV-vis光谱和TEM表征研究表明,分子代数越大,制备的金纳米粒子直径越小,粒径分布越均匀,在DMF溶剂中越稳定.     

胺基端基树状分子在铜纳米粒子形成过程中的模板及稳定化作用

通过Micheal加成和胺解的交替反应,制得末端基为氨基的聚酰胺-胺型树状分子（PAMAM）;研究了第7代PAMAM（G7-NH2）在制备铜纳米粒子过程中的模板作用,通过紫外光谱和透射电镜表征了铜粒子的形成过程以及所得铜粒子的大小。结果表明,铜离子不仅与G7-NH2内部叔胺基形成络合物,还与树状分子外部的伯胺基形成络合物;在得到铜粒子的过程中,G7-NH2具有内模板和外模板作用,铜纳米粒子的尺寸随着铜离子与G7-NH2浓度比例的提高而增大;同时,由于铜纳米粒子为G7-NH2模板所包裹,使其在水中具有良好的分散均匀性和稳定性。但在有氧条件下,铜粒子很容易被氧化为G7-NH2（Cu^2＋）n络合离子。     

以PAMAM树形分子为模板剂纳米氧化锌的制备及其光催化性能研究

以3.5代端酯基PAMAM树型分子为模板,成功制备了颗粒均匀的纳米氧化锌.采用TEM、XRD及UV-vis等手段对合成样品的形貌和结构进行表征.初步探讨了纳米ZnO形成的可能模板机理.测试其在紫外光作用下光降解罗丹明B的性能,结果表明,该法制备的纳米ZnO具有很高的光催化活性.     

水溶液中低代TEG—PAMAM树形分子存在下金纳米颗粒的制备

在水溶液中低代TEG—PAMAM树形分子存在时，用NaBH4还原HAuCI4制备出金纳米颗粒。用紫外可见吸收光谱（UV—Vis），红外光谱（FT-IR）和透射电子显微镜（TEM）对所制备的金纳米颗及其制备过程进行了表征，实验结果表明，以低代树形分子为模板，当HAuCI4与TEG—PAMAM物质量的比分别为2：1，1：1和1：2时，所制的金纳米颗粒的粒径分别为3．5±0．4nm，2．6±1．6nm和2．88±1．33nm，并且可在室温下储存数月。     

PS-b-PAA模板制备金纳米颗粒

以两亲性嵌段共聚物苯乙烯-丙烯酸两嵌段共聚物(PS-h-PAA)在选择性溶剂甲苯中形成的胶束为模板，制得了尺寸均匀的金纳米颗粒，使用透射电镜和紫外吸收光谱对制得的纳米颗粒进行了表征。实验发现PS-h-PAA羧酸基团与HAuCl4有弱的相互作用；改变HAuCl4与羧酸基团的摩尔比可以得到不同尺寸的纳米颗粒；当体系中HAuCl4与羧酸基团摩尔比大于0．3时，过量的HAuCl4不能进入胶束核内，而是在溶剂中析出，纳米颗粒尺寸也不再随之增大。     

聚[9-甲基-9-(8-硫代乙酸辛酯基)-芴]的合成及其金纳米粒子复合物

合成了一种新型的侧链含硫代乙酸辛酯基的聚芴衍生物,聚[9-甲基-9-(8-硫代乙酸辛酯基)-芴](PFMOTA).用这种聚合物修饰金纳米粒子,得到了稳定的PFMOTA/金纳米粒子复合物.采用TEM、GPC、FTIR、UV-vis和PL光谱对聚合物及其修饰的金纳米粒子复合物的结构和性能进行了表征.     

种子生长法制备长径比为2-5的金纳米棒

报道了种子生长法合成金纳米棒.以氯金酸(HAuCl4)为原料,以硼氢化钠(NaBH4)为还原剂,首先还原金离子(Au3 )得到直径为3-4nm的金种子.以银离子(Ag )为辅助离子,以十六烷基溴化铵(CTAB)为表面活性剂,以抗坏血酸为弱还原剂,加入金种子溶液之后可以获得纳米棒.研究表明,通过改变银离子的用量可以控制金纳米棒长径比为2-5.TEM和UV-vis光谱的表征证实了金纳米棒的形貌和光谱特征,并深入探讨了金纳米棒的生长机理.     

笼状PAMAM模板纳米钯催化Suzuki反应

针对PAMAM模板纳米钯催化剂在循环使用中容易团聚产生钯黑的问题,文章利用4．5代PAMAM端基的酯基团与乙二胺反应形成鸟笼状大分子,以其为模版合成纳米钯催化剂,研究发现,当端基连接50％,反应条件温和,催化剂易于分离,循环使用4次,仍能保持70％的收率。     

聚乙烯基吡咯烷酮稳定的离子液体基金纳米流体的制备及稳定性研究

在离子液体/水双液相体系中,以聚乙烯基吡咯烷酮(PVP)为萃取剂,将[AuCl4]-从水相萃取到离子液体相中。在超声辅助条件下用四氢硼钠将离子液体相中的金离子还原,制备了金/1-丁基-3-甲基咪唑六氟磷酸(Au/[BMIm]PF6)纳米流体。制得的金纳米流体用纳米粒度仪和透射电子显微镜进行表征,结果表明,金纳米粒子的平均粒度在11.7nm左右,在离子液体中分布均匀;红外光谱分析结果表明,PVP与金纳米粒子之间存在化学键合作用,对纳米金具有表面修饰的作用,PVP不仅增强了金纳米粒子在离子液体中的溶解性,而且提高了纳米金的抗氧化能力并有效阻止了金纳米粒子间的团聚,使得金纳米粒子在离子液体中有良好的分散性和稳定性。     

Amine-terminated TEG-derived PAMAM dendrimer as template for preparation of gold nanoparticles in water

Nano-sized monodisperse gold particles (AuNPs) have received significant attention in the past decade, due to their unique physical properties and good chemical stability, which can lead to a wide variety of potential applications. In this work, TEG-derived PAMAM dendrimers with amine-terminating groups were synthesized and characterized by ¹H NMR and FT-IR. These dendrimers were investigated as the templates for preparation of gold nanoparticles through the reduction of HAuCl₄ by NaBH₄ in water. Stable gold nanoparticles with diameters around 10 nm were obtained in the presence of G2.0 – G5.0 dendrimers and characterized by UV-Vis spectroscopy, transmission electron microscopy (TEM) and dynamic light scattering (DLS). The particle size of the produced AuNPs decreased with increasing dendrimer generations. A dendrimer of higher generation has a rigid structure with many end groups on the surface and may play a powerful role in the growth of the AuNPs, as well as having a solid stabilization effect on the AuNPs.     

Amine-terminated TEG-derived PAMAM dendrimer as template for preparation of gold nanoparticles in water

Nano-sized monodisperse gold particles (AuNPs) have received significant attention in the past decade, due to their unique physical properties and good chemical stability, which can lead to a wide variety of potential applications. In this work, TEG-derived PAMAM dendrimers with amine-terminating groups were synthesized and characterized by ¹H NMR and FT-IR. These dendrimers were investigated as the templates for preparation of gold nanoparticles through the reduction of HAuCl₄ by NaBH₄ in water. Stable gold nanoparticles with diameters around 10 nm were obtained in the presence of G2.0–G5.0 dendrimers and characterized by UV-Vis spectroscopy, transmission electron microscopy (TEM) and dynamic light scattering (DLS). The particle size of the produced AuNPs decreased with increasing dendrimer generations. A dendrimer of higher generation has a rigid structure with many end groups on the surface and may play a powerful role in the growth of the AuNPs, as well as having a solid stabilization effect on the AuNPs.     

Preparation and catalytic activity of Au-Pd, Au-Pt, and Pt-Pd binary metal dendrimer nanocomposites

Catalytic activity of Au-Pt, Au-Pd, and Pt-Pd dendrimer nanocomposites for reduction of p-nitrophenol was investigated in water. The bimetallic dendrimer nanocomposites were prepared by simultaneous reduction with sodium borohydride in the presence of poly(amidoamine) (PAMAM) dendrimers with amine and carboxyl terminal groups. Average diameters of the obtained particles were 2-4 nm by transmission electron microscopy. From UV-vis spectroscopy, it was found that the particles were not mixtures of monometallic particles but binary ones. X-ray photoelectron spectroscopy showed that formation of binary composite particles prevents palladium atoms from oxidation. The Au-Pd and Pt-Pd binary particles exhibited higher catalytic activity than monometallic ones. On the other hand, catalytic activity of Au-Pt binary particle was comparable to that of platinum nanoparticles.     

树状大分子包裹的金纳米颗粒对PCR优化的影响

以283bp的λDNA的再扩增PCR体系为测试体系,对树状大分子包裹的金纳米颗粒对PCR的作用进行研究,实验证明,包裹有不同浓度胶体金的树状大分子都能对PCR反应起到优化作用,而且随着胶体金浓度的增大,相应树状大分子的优化作用增强,最优浓度越来越低,结果表明,树状大分子包裹的金纳米颗粒的优化机制是胶体金的加入,使树状大分子的＂硬度＂增大,当树状大分子与PCR各组分相互作用时,由于其表面的有效反应基团增多,提高周围PCR各组分有效反应浓度,从而增强反应的效率及特异性。     

Direct formation of platinum nanoparticles by internally isopropanol-modified dendritic poly(amido amine)

We report a reducing agent-free method for preparing platinum (Pt) nanoparticles by internally isopropanol (IPA)-modified dendritic poly(amido amine) (PAMAM). The internally modified dendritic PAMAM were synthesized via divergent strategy using 1,3-diaminopropanol as a linking spacer, and NMR analyses confirm the embedded IPA moieties within the dendrimers by the appearance of characteristic proton and carbon resonances at 3.81 and 67.9 ppm, respectively. The in situ formation of stable Pt colloids was carried out by thermal treatment in the presence of internally modified dendritic PAMAM bearing either ester or alcohol peripherals, suggesting that the internal IPA functionalities dominate the reduction of Pt4+ ions. Moreover, the overall reducing rate was accelerated with increasing pH values. This result agreed with a reaction feature for preparing metal nanocomposites through polyol process in which basic environment facilitates the thermal-promoted reduction of metal ions accompanied with the oxidation of internal hydroxyl groups. The morphology of the dendrimer/Pt composite monitored by a transmission electron microscope (TEM) exhibited narrowly dispersed and roughly spherical shaped nanoparticles with a mean diameter of 5.4 nm.     

Synthesis and characterization of quaternized carboxymethyl chitosan/poly(amidoamine) dendrimer core–shell nanoparticles

With the aim to develop a novel water-soluble modified chitosan nanoparticle with tuned size and improved antibacterial activity, quaternized carboxymethyl chitosan/poly(amidoamine) dendrimers (CM-HTCC/PAMAM) were synthesized. Firstly low-generation amino-terminated poly(amidoamine) (PAMAM) dendrimers were prepared via repetitive reactions between Michael addition and amidation, which were then employed for modifying quaternized carboxymethyl chitosan (CM-HTCC). Prior to the reaction of CM-HTCC with PAMAM, carboxylic groups in CM-HTCC were activated with EDC/NHS in order to enhance the reaction efficiency. FT-IR, ¹H NMR, elemental analysis and XRD were performed to characterize CM-HTCC/PAMAM dendrimers. Turbidity measurements showed that CM-HTCC/PAMAM dendrimers had good water-solubility. TEM images indicated that CM-HTCC/PAMAM dendrimers existed as smooth and spherical nanoparticles in aqueous solution. The results of antibacterial activity explored that CM-HTCC/PAMAM dendrimer nanoparticles displayed higher antibacterial activity against Gram-negative bacteria Escherichia coli (E. coli), whereas they showed much less efficiency against Gram-positive bacteria Staphylococcus aureus (S. aureus) compared to quaternized chitosan (HTCC).     

Potentiometric response characteristics of polycation-sensitive membrane electrodes toward poly(amidoamine) and poly(propylenimine) dendrimers

The potentiometric response characteristics of polycation-sensitive membrane electrodes toward two classes of polycationic dendrimers are examined. Using appropriately formulated polymer membrane electrodes composed of a dinonylnaphthalenesulfonate (DNNS) salt in a plasticized polyurethane matrix, it is shown that poly(amidoamine) (PAMAM) and poly(propylenimine) (PPI) dendrimers are readily detected at submicrogram per milliliter levels via a nonequilibrium response mechanism. The relationship between the total EMF response (at equilibrium) and the specific dendrimer structure is also examined. For both the PAMAM and PPI species, it is shown that the total EMF response does not change significantly with dendrimer generation number; however, the nonequilibrium analytically useful response curves are shifted to higher mass concentrations as the generation number is increased. The relative contributions of the terminal primary amines and the interior tertiary amines of the dendrimers to the observed EMF response are investigated by synthesis of various dendrimer derivatives (acetylated, quaternized, etc.). By comparing the total EMF responses for these derivatives as a function of sample pH, it is demonstrated that the lipophilic cation exchanger (DNNS) within the membrane phase can likely interact electrostatically with both protonated forms of the terminal primary amines and interior tertiary amines of the dendrimer structures. The practical application of the nonequilibrium potentiometric detection of dendrimers for monitoring their interaction with DNA is also demonstrated.