Properties of Dendrimer‐Encapsulated Pt Nanoparticles Doped Polypyrrole Composite Films and Their Electrocatalytic Activity for Glucose Oxidation

A type of novel electroanalytical sensing nanobiocomposite material was prepared by electropolymerization of pyrrole containing poly(amidoamine) dendrimers‐encapsulated platinum nanoparticles (Pt‐PAMAM), and glucose oxidase (GOx). The Pt nanoparticles encapsulated in PAMAM are nearly monodisperse with an average diameter of 3 nm, and they provide electrical conductivity. Polypyrrole acts as a polymer backbone to give stable and homogeneous cast thin films, and it also defines the electrical conductivity. Both Polypyrrole and PAMAM can provide a favorable microenvironment to keep the bioactivity of enzymes such as glucose oxidase. The homogeneity of GOx/Pt‐PAMAM‐PPy nanobiocomposite films was characterized by atomic force microscopy (AFM). Amperometric biosensors fabricated with these materials were characterized electrochemically using cyclic voltammetry (CV), electrochemical impedance spectra (EIS) and amperometric measurements in the presence of hydrogen peroxide or glucose. All those show the resultant biosensor sensitivity was strongly enhanced within the nanobiocomposite film. The optimized glucose biosensor displayed a sensitivity of 164 μA mM^?1 cm^?1, a linear range of 0.2 to 600 μM, a detection limit of 10 nM, and a response time of <3 s.     

Synthesis and photoresponsive study of azobenzene centered polyamidoamine dendrimers

A new series of novel polyamidoamine (PAMAM) dendrimers 4, 5 and 6 possessing azobenzene units specifically at the core were prepared and their reversible trans/cis photoisomerization properties were studied. PAMAM dendritic wedges as well as azo-based PAMAM dendrimers were fully characterized by means of FT-IR, NMR (¹H and ¹³C), mass spectrometry (MALDI-MS), thermogravimetric and elemental analysis.     

Self-organization and photoreactivity of anthryl dendron having perfluoroalkyl chains at the terminals

A newly designed anthryl dendron having perfluoroalkyl chains at terminals showed thermotropic liquid crystallinity, which was characterized using polarizing optical microscopy, differential scanning calorimetry, and X-ray diffraction. The anthryl dendron forms S_B phase at room temperature below 53 °C, at which temperature a phase transition to Col_rd takes place. In a fluorous solvent, regioselective photodimerization of the anthryl dendron occurred to give head-to-head photodimers, although photodimerization in the S_B phase and chloroform gave both head-to-head and head-to-tail photodimers.     

Novel CO2 selectively permeating membranes containing PETEDA dendrimer

Pentaerythrityl tetraethylenediamine (PETEDA) dendrimer was synthesized from pentaerythrityl tetrabromide and ethylenediamine. Its molecular structure was characterized by elemental analysis, Fourier transform infrared resonance (FT-IR) and hydrogen nuclear magnetic resonance (¹H NMR) spectroscopy. The composite membranes for selectively permeating CO₂ were prepared by using PETEDA-PVA blend polymer as the active layer and polyethersulfone (PES) ultrafiltration membrane as the support layer and their permselectivity was tested by pure CO₂ and CH₄ gases and the gas mixture containing 10 vol.% CO₂ and 90 vol.% CH₄, respectively. For pure gases, the membrane containing 78.6 wt% PETEDA and 21.4 wt% PVA in the blend has a CO₂ permeance of 8.14 × 10⁻⁵ cm³ (STP) cm⁻² s⁻¹ cmHg⁻¹ and CO₂/CH₄ selectivity of 52 at 143.5 cmHg feed gas pressure. While feed gas pressure is 991.2 cmHg, CO₂ permeance reaches 3.56 × 10⁻⁵ cm³ (STP) cm⁻² s⁻¹ cmHg⁻¹ and CO₂/CH₄ selectivity is 19. For the gas mixture, the membrane has a CO₂ permeance of 6.94 × 10⁻⁵ cm³ (STP) cm⁻² s⁻¹ cmHg⁻¹ with a CO₂/CH₄ selectivity of 33 at 188.5 cmHg feed gas pressure, and a CO₂ permeance of 3.29 × 10⁻⁵ cm³ (STP) cm⁻² s⁻¹ cmHg⁻¹ with a CO₂/CH₄ selectivity of 7.5 at a higher feed gas pressure of 1164 cmHg. A possible gas transport mechanism in the composite membranes is proposed by investigating the permeating behavior of pure gases and the gas mixture and analyzing possible reactions between CO₂/CH₄ gases and the PETEDA-PVA blend polymer. The effect of PETEDA content in the blend polymer on permselectivity of the composite membranes was investigated, presenting that CO₂ permeance and CO₂/CH₄ selectivity increase and CH₄ permeance decreases, respectively with PETEDA content. This is explained by that with increasing PETEDA content, the carrier content increases, and the crystallinity and free volume of the PETEDA-PVA blend decrease that were confirmed by the experimental results of X-ray diffraction spectra (XRD) and positron annihilation lifetime spectroscopy (PALS).     

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.     

超支化聚(胺酯)的分子设计及其制备

以丙烯酸甲酯和二乙醇胺为原料由Michael加成反应制得N ,N 二羟乙基 3 胺基丙酸甲酯单体 ,再用“准一步法”和“发散法”使之与 1 ,1 ,1 三羟甲基丙烷 (核 )反应合成一种新型超支化聚 (胺 酯 ) .以核磁共振和元素分析方法对N ,N 二羟乙基 3 胺基丙酸甲酯单体的分子结构进行了表征 .GPC测定表明合成的超支化聚 (胺 酯 )分子量分布窄 ,具有单分散性 ;粘度小于同分子量的线形分子 ;耐热性能较好 ,失重温度高于2 0 0℃ .     

Oxidation of Cyclohexene Catalyzed by PAMAM—SA—M Dendrimers

Oxidation of cyclohexene under 1 atmospheric pressure of molecular oxygen at 70℃ in the absence of solvent catalyzed by PAMAM-SA-M(Where PAMAM=polyamidoamine;SA=salicyaldehyde;M=metal ions Fe^3 ,Co^2 ,Ni^2 ,Mn^2 ,Cu^2 ,Zn^2 ,respectively) dendrimers, afforded 2-cyclohexen-1-ol 1,2-cyclohexen-1-one 2,7-oxabicyclo [4,1,0] heptane 3 and 7-oxabicyl [4,1,0] heptan-2-one 4 as the major products. The factors that affect this reaction are also discussed.     

大核树枝状大分子的合成及其凝血、溶血性能研究

从 8 0年代中期开始 ,Ｔｏｍａｌｉａ、Ｎｅｗｋｏｍｅ、Ｆｒｅｃｈｅｔ等对树枝状大分子开展了卓有成效的研究 ,合成了多种结构的树枝状大分子[1 ] ,并对它们的应用进行了积极的探讨 .在数枝状大分子的合成方面 ,寻找新的多官能团引发核就是一个研究热点 ,例如采用大分子核 ,Ｆｒｅｃｈｅｔ等采用聚乙二醇作为核用收敛法合成了聚芳醚和聚芳酯树枝状大分子[2 ,3] ,为嵌段共聚增添了新的内容 .而Ｔｏｍａｌｉａ等以氨和乙二胺等小分子为核合成的聚酰胺 胺类树枝状大分子呈粘糊状[4] ,取样、称量等操作很麻烦 ,其应用也受到限制 .聚乙二醇无毒…     

Preparation of Dendrimers from Macromolecular Cores and Papain Immobilization

Recently,stIJdyonpreparationandpotentialapplicationofdendrimersisquiteactivel-3.StrIJcturally,therearealotoffunctionalgroupsonthesurfaceofadendrimer,whicharepossiblyusedtoconnectwithbiocatalystsuchasenZymeandcell.However,inmostcasesthereporteddendrimerswereviscousandcouldhardlybeusedascarrierforenZymeimmobilization.Inordertoobtainsoliddendrimers,amino-poly(ethyleneglycol)[PEG(NH,),]andamino-propylsilicagel[SG(NH,).]wereselectedastWomacroinitiatorcores(MC)toprepareMC-dendrimers(PEG-den…     

Photodegradation of PAMAM G5-stabilized aqueous suspensions of gold nanoparticles

Gold nanoparticles are produced in the form of colloidal suspensions in water by ps laser ablation of a metallic target. The fifth generation of ethylenediamine-core poly(amidoamine) (PAMAM G5) is used as a capping agent. Thanks to the ability of PAMAM to encapsulate and stabilize gold cations within its inner cavities, it is possible to evidence, by simple UV-visible spectroscopy, a photo-fragmentation process induced by the 532 nm radiation, which is resonant with the absorption plasmon band of gold nanoparticles. This effect, that can be also exploited to control the size and shape of gold nanoparticles obtained with different procedures, arises from electron photo-ejection and subsequent charging and disintegration of existing gold nanoparticles into smaller size products.