Starch-assisted synthesis of polypyrrole nanowires by a simple electrochemical approach

Starch, one of the most commonly used polysaccharides, has been adopted for the first time as morphology-directing agent to the electrochemical synthesis of polypyrrole (PPy) nanowires on various electrodes

光纤毫米波融合接入系统能量效率分析

随着高速移动通信需求的持续增长,"绿色通信"成为近期的研究热点。文章提出一种使用谐波生成毫米波的技术,同时结合ROF（光载无线）技术实现光纤/无线融合接入系统,该系统使用毫米波微微蜂窝接入网技术为室内移动终端提供接入服务。在此基础上,文章对上述系统进行了能量效率分析,通过与WLAN（无线局域网）接入方式的能量效率分析对比,表明该系统具有更高的数据速率和能量效率

pH-sensitive characteristics of poly(acrylic acid)-functionalized anodic aluminum oxide (AAO) membranes

A simplified method to prepare pore-filled pH-responsive membranes was provided by using anodic aluminum oxide (AAO) membrane as supported matrix. To introduce reactive groups for grafting weak polyelectrolyte, silica-AAO composite membrane was prepared by depositing silica onto the AAO membrane through sol-gel method. The obtained composite membrane keeps the ideal pore structures of the original AAO membrane. Poly(acrylic acid) as responsive polymer was grafted onto the silica-AAO composite membranes by activating with 3-glycidoxypropyl trimethoxysilane. The obtained pH-responsive membranes showed evident pH-sensitivity, and the pH-valve effect was observed at the pH between 3 and 5. Electrochemical impedance spectroscopy demonstrates the membrane resistance increases from 4.3 x 10(5) Omega cm(2) at pH 2 to 1.3 x 10(6) Omega cm(2) at pH 6. (C) 2011 Elsevier B.V. All rights reserved.National Nature Science Foundation of China[30870648, 30870617, 30500127, 31070845]; Natural Science Found of Fujian Province[C0510005

Functionalized Silica Nanotubes As Affinity Matrices for Bilirubin Removal

Arginine-immobilized silica nanotubes as affinity matrices were fabricated for bilirubin removal. The silica nanotubes were prepared by depositing silica within the alumina membrane through sol-gel method. Ligand arginine was immobilized on the inner and outer surfaces of silica nanotubes by activating with glutaraldehyde. The content of arginine of affinity matrices was similar to 20.1 mg/g nanotubes. Such arginine-immobilized affinity matrices were used to adsorb bilirubin from the bilirubin-phosphate solution and bilirubin-albumin solution. The effects of temperature, ionic strength, albumin concentration, and the adsorption mechanism were investigated by batch experiments. The results showed arginine-immobilized silica nanotubes achieved excellent adsorption capacity for bilirubin (similar to 63.6 mg/g nanotubes).National Nature Science Foundation of China[30870648, 30870617, 30500127]; Natural Science Foundation of Fujian Province[C0510005

Heparin-controlled growth of polypyrrole nanowires

Heparin, a potent anticoagulant, has been used for the first time for the synthesis of PPy nanowires serving not only as an anion dopant but also as an effective morphology-directing agent. The obtained PPy nanowires exhibit long and fine structures with smooth surface and the average diameter of the nanowires is about 90-100 nm and lengths are several hundred nanometers to micrometers. The possible formation mechanism of PPy nanowires may be related to the chain structure of heparin with functional groups (-SO3- and -COO-) on the surface. The effect of concentrations of pyrrole monomers and heparin on the. morphology and size of PPy nanowires has been investigated

Heparin-doped affinity electromembranes for thrombin purification

Heparin-doped affinity electromembrane was fabricated by synthesizing conducting polymers polypyrrole onto porous polyethersulfone membrane using heparin as both ligand and dopant. The obtained affinity electromembrane exhibited a uniform conductivity value of 1.73 x 10(-4) S/cm. The content of heparin of affinity electromembrane was similar to 0.894 mg/g membrane. Such heparin-doped affinity electromembranes were used to purify thrombin. The adsorption mechanism of thrombin and the effects of temperature, initial concentration of thrombin and potential on adsorption were investigated by batch experiments. The results showed that the adsorption capacity increased with increasing the temperature, initial concentration of thrombin and potential, and the adsorption isotherm fitted the Freundlich model well. Elution of protein showed desorption ratio was up to 93.1% using 2.0 M NaSCN solution as the desorption agent. The adsorption capacities of all the tested affinity electromembranes did not significantly change during the repeated adsorption-desorption operations. (C) 2011 Elsevier B.V. All rights reserved.National Nature Science Foundation of China[30870648, 30870617, 30500127, 31070845]; Natural Science Found of Fujian Province[C0510005

Nanowire-Based Polypyrrole Hierarchical Structures Synthesized by a Two-Step Electrochemical Method

National Nature Science Foundation of China [30500727, 30870617, 30870648]A simple two-step electrochemical method is proposed for the synthesis of nanowire-based polypyrrole hierarchical structures. In the first step, microstructured polypyrrole films are prepared by electropolymerization. Then, polypyrrole nanowires are electrodeposited on the surface of the as-synthesized microstructured polypyrrole films. As a result, hierarchical structures of polypyrrole nanowires on polypyrrole microstructures are obtained. The surface wettabilities of the resulting nanowire-based polypyrrole hierarchical structures are examined. It is expected that this two-step method can be developed into a versatile route to produce nanowire-based polypyrrole hierarchical structures with different morphologies and surface properties

Synthesis of polypyrrole nanowire network with high adenosine triphosphate release efficiency

A novel drug release system based on polypyrrole (PPy) nanowire network is developed for controlled adenosine triphosphate (ATP) release. Interestingly, the formation of the PPy nanowire networks is induced by ATP itself. i.e. ATP serves as both the morphology-directing agent and the model drug. More importantly, it should be pointed out that using ATP as morphology-directing agent for the formation of the PPy nanowire network can significantly increase the ATP release efficiency due to the high surface area of the resulting nanowire network. The experiment results show that ATP release efficiency increases from 53% (for conventional cauliflower-like PPy) to 90% (for PPy nanowire network) within 45 h upon electrical stimulation. (C) 2011 Elsevier Ltd. All rights reserved.National Nature Science Foundation of China[31070845, 30870617, 30870648, 30500127

Affinity electromembrane with covalently coupled heparin for thrombin adsorption

A new composite membrane with electrical conductivity and reactive groups (-COOH) was synthesized by copolymerizing pyrrole-3-carboxylic acid and pyrrole onto nylon membrane via the template method. The ligand, heparin, was covalently coupled onto the composite membrane by activating with N-hydroxysuccinimide and 1-ethyl-3[-3-(dimethylamino)propyl]carbodiimide and modified with ethylenediamine. The as-synthesized affinity electromembrane exhibited a uniform conductivity value of 3.7 x 10(-7) S/cm and the content of heparin was approximately 1.897 mg/g membrane. By applying an electrical stimulation (-0.5 V) to the affinity electromembrane, the adsorption capacity and rate were greatly enhanced. Elution of protein showed desorption ratio was up to 92.7% using 2.0 M NaSCN solution as the desorption agent. To investigate the performance of dynamic adsorption of heparin-coupled affinity electromembrane, a membrane cartridge to which electrical stimulation can be applied was designed. The result of dynamic separation showed that the time of breakthrough was delayed from 22 min in the absence of electrical stimulation to 31 min in the presence of electrical stimulation. (C) 2012 Elsevier B.V. All rights reserved

Chemically Modified PPyCOOH Microtubes as an Affinity Matrix for Protein Purification

Novel affinity microtubes, with high ligand content and adsorption capacity of proteins, were fabricated by functionalization of the carboxyl group on the inner and outer surfaces of conductive polymer, poly(1(2-carboxyethyl)pyrrole) (PPyCOOH) microtubes with iminodiacetic acid (IDA), which affords the active site to form metal-IDA chelates used for immobilized-metal affinity chromatography. After immobilization with copper ions, the microtubes were used to recover a model protein, bovine hemoglobin, from red cell lysate in a batch manner. The protein adsorption indicates that the affinity microtubes exhibit a high adsorption capacity and good selectivity, and the adsorption isotherm fitted the Freundlich model well. Elution of the protein showed that the desorption ratio was up to 99.5% in 3 h, using 0.2 M. CH3COOH-CH3COONa buffer solution (pH = 3.6) as the desorption agent. The adsorption-desorption cycle was repeated 10 times using the same microtubes without significant loss in the hemoglobin adsorption capacity.National Nature Science Foundation of China [30870648, 30870617, 30500127]; Natural Science Foundation of Fujian Province [C0510005