铂支撑的碘-聚吡咯修饰双层脂膜的I-V特性

首次在铂丝新生表面上形成了碘-聚吡咯双层脂膜,用循环伏安法研究了碘掺杂浓度对双层脂膜I-V特性的影响。用此法所得到的铂支撑双层脂膜十分稳定,可进一步用于生物传感器及分子电子器件的基础与应用研究。     

瘤背石磺低频听力基因PMCA2的克隆、相对表达及神经组织原位杂交分析

低频听力基因PMCA2在生物听力方面占据着重要位置,基因突变或缺失后会引发神经性耳聋和平衡功能障碍.为探究基因PMCA2在瘤背石磺潮汐感知中的作用,本研究通过RACE技术克隆得到瘤背石磺PMCA2基因的全长cDNA,并进行系统进化分析.利用实时荧光定量PCR(RT-qPCR)技术和原位杂交技术分析两组(暂养无处理组和潮汐干扰刺激组)瘤背石磺PMCA2基因在各组织中相对表达量和在神经组织各神经节中的相对表达部位.实验结果表明,瘤背石磺PMCA2基因cDNA全长5 091 bp,包含492 bp的5'非编码区(UTR)以及972 bp的3'UTR,3 627bp的开放阅读框,共编码1 208个氨基酸,基因序列较为保守.序列分析结果显示,瘤背石磺与加州海兔、绿色海蜗牛和福寿螺PMCA2氨基酸序列同源性分别为81.79％,78.25％和72.91％.通过系统进化树分析研究得出,瘤背石磺与加州海兔进化关系相对较近.RT-qPCR结果显示,两组石磺神经组织PMCA2基因表达量皆高于其他组织的,且潮汐干扰刺激组神经组织表达量明显高于暂养无处理组,有显著性差异.两组瘤背石磺神经组织原位杂交实验结果显示,相较于暂养无处理组,潮汐干扰刺激组石磺神经组织杂交信号明显增强,该结果与荧光定量PCR结果相符.实验初步表述了瘤背石磺PMCA2基因的生物信息学特征,在瘤背石磺各组织中的表达情况及在神经组织中的分布部位,为研究滩涂生物感知潮汐能力提供原创性成果.     

依赖PQQ甲醇脱氢酶对底物催化专一性差的原因分析

采用甲基营养杆菌NO .2为实验菌株 ,经超声波破细胞 ,酸处理 ,DEAE 纤维素和CM 纤维素柱层析等改进的纯化程序 ,可得到比活力为 12 .5u/mg的甲醇脱氢酶 (MDH)样品。该酶在测活系统中除能氧化甲醇等醇类化合物外 ,还能以较大速率氧化氯化铵、甲胺、脲等物质 ,MDH对不同底物亲和力的差异性主要取决于其辅基吡咯喹啉醌 (PQQ)与底物的结合力。甲醇脱氢酶与底物结合前后在特定区域的光谱有一定的差异性     

Prx1 对细胞信号转导过程的调控

Prx1是一种高等生物体内广泛表达的抗氧化酶,在细胞处于不同的氧化状态时,能够以二聚体和十聚体两种不同的形式存在。该蛋白不仅能起到抗氧化和调节H2O2介导的信号转导作用,同时还能发挥分子伴侣的功能,通过细胞信号网络,直接或间接地参与体内多种与氧化相关的生理病理过程,发挥体内氧化还原调节器的重要作用。     

人脐带间充质干细胞于不同通电情况下在聚吡咯上生长情况的形态

目的观察人脐带间充质干细胞（human umbilical cord mesenchymal stem cell,hUC-MSC）与聚吡咯共培养后,在不同通电条件下形态学变化。方法体外分离培养hUC-MSC并进行鉴定。循环伏安法制备聚吡咯（polypyrrole,PPy）薄膜。选择第3～6代的hUC-MSC与PPy共培养,分别采用控制电压和控制电流的方法对细胞进行刺激,利用电镜及光镜观察细胞形态学变化。不通电组作为阴性对照。结果电刺激对细胞贴附、形态有较大影响,不同形式的电刺激对细胞形态影响的比较类似。结论电刺激结合生物导电材料对细胞的贴附和形态可造成显著改变,可作为调控细胞生长的手段之一,需要进一步研究其控制条件。     

吡咯赖氨酸：第 22 种参与蛋白质生物合成的氨基酸

吡咯赖氨酸在产甲烷菌的甲胺甲基转移酶中发现,是目前已知的第 22 种参与蛋白质生物合成的氨基酸,与标准氨基酸不同的是,它由终止密码子 UAG 的有义编码形成 . 与之对应的在产甲烷菌中也含有特异的吡咯赖氨酰 -tRNA 合成酶 (PylRS) 和吡咯赖氨酸 tRNA (tRNA^Pyl). tRNA^Pyl具有不同于经典 tRNA 的特殊结构 . 产甲烷菌通过直接途径和间接途径这两种途径生成吡咯赖氨酰 -tRNA^Pyl(Pyl-tRNA^Pyl) ,它还可能通过 mRNA 上的特殊结构以及其他还未发现的机制,控制 UAG 编码成为终止密码子或者吡咯赖氨酸 . 比较了吡咯赖氨酸与另一种非标准氨基酸,第 21 种氨基酸———硒代半胱氨酸的相似点与不同点 .     

葡萄糖有氧氧化和ATP的生成量

能量是一切生物体活动所必需的。生物体所需的能量一般来自于体内有机物的氧化。糖、脂肪、蛋白质等有机物在细胞内氧化分解 ,释放出二氧化碳、水和能量的过程称生物氧化。生物氧化包括许多复杂的生物化学反应 ,不同的有机物虽有各自的分解氧化过程 ,但最终都经历共同的终末代谢途径。总体包括四个阶段 (图 1 )。生物氧化中的能量代谢具有两个明显的特点 :一是生物氧化中能量是逐步缓慢释放的 ,这样放出的能量易得到最有效的利用 ;其次 ,生物氧化过程产生的能量通常先贮存在能量通货ＡＴＰ中 ,通过ＡＴＰ再满足机体的能量需要 ,并且ＡＴＰ主…     

一株高锰氧化活性大肠杆菌的分离鉴定和多铜氧化酶基因的克隆与结构特性

锰氧化物是Mn(Ⅱ)经生物和化学氧化后形成的矿物成分,在元素生物地球化学循环过程中起着重要作用,而不同种类的细菌对Mn(Ⅱ)的氧化作用是自然界中氧化锰矿物形成的主要成因.从山东崅峪采集的铁锰结核棕壤中分离得到一株具有高锰氧化活性的土壤杆菌,其对Mn(Ⅱ)的氧化作用活性明显高于其它分离菌株,达到65 μmol/L.通过个...     

吡咯喹啉醌生物合成研究进展

吡咯喹啉醌(PQQ)是一种较新近发现的氧化还原酶的辅酶,对微生物及动植物均具有重要生理作用。已知能产生PQQ的生物仅限于某些革兰阴性细菌,已分离得到几种不同来源的PQQ生物合成基因,其序列具有一定的保守性。PQQ的生物合成涉及4～7个基因,这些基因一般成簇排列。业已证明,谷氨酸和酪氨酸是PQQ合成的前体物质。对各个基因的功能已有不同程度的了解,但PQQ的生物合成途径还尚未阐明。     

吡咯喹啉醌及其生理功能

吡咯喹啉醌（ＰＱＱ）──一种新的氧化还原酶辅基,存在于一些微生物、植物和动物组织中,参与催化生物体内氧化还原反应。研究表明ＰＱＱ具有一些重要生理功能：刺激某些植物发育及微生物和人体细胞生长;作为动物体生长发育的必需因子;清除自由基保护机体免受自由基损害;防治肝损伤;促进神经生长因子合成等。因此,ＰＱＱ具有一定的医药应用前景。     

Improved cellular response on functionalized polypyrrole interfaces

Neuroregeneration strategies involve multiple factors to stimulate nerve regeneration. Neural support with chemical and physical cues to optimize neural growth and replacing the lesion neuron and axons are crucial for designing neural scaffolds, which is a promising treatment approach. In this study, polypyrrole polymerization and its functionalization at the interface developed by glycine and gelatin for further optimization of cellular response. Nanofibrous scaffolds were fabricated by electrospinning of polyvinyl alcohol and chitosan solutions. The electrospun scaffolds were polymerized on the surface by pyrrole monomers to form an electroactive interface for further applications in neural tissue engineering. The polymerized polypyrrole showed a positive zeta potential value of 57.5 ± 5.46 mV. The in vitro and in vivo biocompatibility of the glycine and gelatin-functionalized polypyrrole-coated scaffolds were evaluated. No inflammatory cells were observed for the implanted scaffolds. Further, DAPI nucleus staining showed a superior cell attachment on the gelatin-functionalized polypyrrole-coated scaffolds. The topography and tuned positively charged polypyrrole interface with gelatin functionalization is expected to be particularly efficient physical and chemical simultaneous factors for promoting neural cell adhesion.     

One pot synthesis of polypyrrole silver nanocomposite on cotton fabrics for multifunctional property

Polymer-silver nanocomposites modified cotton fabrics were prepared by in situ chemical oxidative polymerization using pyrrole and silver nitrate. In a redox reaction between pyrrole and silver nitrate, silver ions oxidize the pyrrole monomer and get reduced. This reduced silver as nanoparticles deposited on/into the polypyrrole/cotton matrix layer and the interaction between silver and polypyrrole was by adsorption or electrostatic interaction. The structure and composite formation on cotton fiber was investigated using SEM, FT-IR, XPS and XRD. The results showed that a strong interaction existing between silver nanoparticles with polypyrrole/cotton matrix. FT-IR studies clearly indicated that the interaction between polypyrrole (NH) and cellulose (>COH) was by hydrogen bonding. It is observed that the conductivity of the composite coated fabrics has been increased by the incorporation of silver nanoparticles. In the synthesized composites, silver content plays an important role in the conductivity and antimicrobial activity rate of the fabrics against gram positive Staphylococcus aureus and gram negative Escherichia coli bacteria.     

Controlled amine functionalization on conducting polypyrrole nanotubes as effective transducers for volatile acetic acid

Pristine (carboxylated) and aminated polypyrrole nanotubes were successfully fabricated using vapor deposition polymerization with a template. In particular, aminated polypyrrole nanotubes were readily synthesized by modifying the nanotube surface with open polyamine chains. Pristine and aminated polymer nanotubes were used as the transducer to acetic acid vapor. Amino-functionalized nanotubes revealed more enhanced sensitivity than the pristine carboxylated nanotubes with the increasing number of amine spacers due to the increased polymer/analyte partition coefficient and mass uptake of the analyte. Moreover, polyamine-functionalized nanotubes presented a reversible and reproducible response to acetic acid up to 40% sensitivity. The aminated polypyrrole nanotubes demonstrated the potential capability to be excellent transducers for volatile fatty acids in disposable sensors.     

A comparative study: Immobilization of yeast cells and invertase in poly(ethyleneoxide) electrodes

Yeast cells (Saccharomyces cerevisiae) and invertase enzyme were immobilized in thiophene capped poly(ethyleneoxide)/polypyrrole (PEO-co-PPy) and 3-methylthienyl methacrylate-co-p-vinyl benzyloxy poly(ethyleneoxide)/polypyrrole (CP-co-PPy) matrices. Immobilization of the enzyme and yeast cells was performed via entrapment in conducting copolymers during electrochemical polymerization of pyrrole through the thiophene moiety of the polymers. Maximum reaction rates, Michaelis–Menten constants, optimum temperature and pH values, operational and storage stabilities of the enzyme and yeast cell electrodes were investigated.     

Honeycomb-structured porous films from polypyrrole-containing block copolymers prepared via RAFT polymerization as a scaffold for cell growth

Honeycomb-structured porous films were prepared using customized amphiphilic block copolymers, synthesized by RAFT polymerization. Pyrrole was templated along an amphiphilic block copolymer, composed of polystyrene and poly(acrylic acid). Subsequent oxidation of pyrrol to polypyrrole, resulted in the formation of a soluble polypyrrole-containing polymer. Gel permeation chromatography and dynamic light scattering studies confirmed the solubility of the resulting customized amphiphilic block copolymer, in both water and organic solvent, forming either micelles or inverse aggregates. Porous films with a hexagonal array of micron-sized pores were generated with the polymer, using the breath figures templating technique. The resulting films were found to be non-cytotoxic and hence suitable as scaffolds for tissue engineering. Initial fibroblast cell culture studies on these scaffolds demonstrated a dependency of cell attachment on the pore size of scaffolds.     

Immobilization of tyrosinase in polysiloxane/polypyrrole copolymer matrices

Immobilization of tyrosinase in conducting copolymer matrices of pyrrole functionalized polydimethylsiloxane/polypyrrole (PDMS/PPy) was achieved by electrochemical polymerization. The polysiloxane/polypyrrole/tyrosinase electrode was constructed by the entrapment of enzyme in conducting matrices during electrochemical copolymerization. Maximum reaction rate (V(max)) and Michaelis-Menten constant (K(m)) were investigated for immobilized enzyme. Enzyme electrodes were prepared in two different electrolyte/solvent systems. The effect of supporting electrolytes, p-toluene sulfonic acid and sodium dodecyl sulfate on the enzyme activity and film morphology were determined. Temperature and pH optimization, operational stability and shelf-life of enzyme electrodes were also examined. Phenolic contents of green and black tea were determined by using enzyme electrodes.     

Two‐Photon polymerization for microfabrication of three‐dimensional scaffolds for tissue engineering application

In natural tissues cells are embedded in a three‐dimensional fibrous network of biopolymers like collagen, hyaluronic acid etc. This extracellular matrix (ECM) influences the cell fate, the differentiation status, metabolic processes and provides structural integrity. For a three‐dimensional or physiological cell cultivation that are required in biomedical applications (e.g. tissue engineering, BioMEMS) scaffolds are needed. These scaffolds mimic the ECM according to their biocompatibility which comprises aspects of surface compatibility and importantly for tissue engineering applications aspects of structural compatibility. We have evaluated scaffold design parameters for the three‐dimensional cultivation of chondrocytes for the tissue engineering of artificial cartilage. Two‐photon polymerization is a powerful technique for fabrication of polymeric three‐dimensional micro‐ and submicro‐structures. The photoinitiation system for two‐photon polymerization is excited by simultaneous absorption of two photons leading to chemical polymerization reactions. Due to a tight confinement of the excitation volume around the focal point, this method can produce micrometer sized objects maintaining a high spatial resolution down to 100 nm. Two‐photon processes require very high photon densities which are provided by pulsed femtosecond lasers. The potential of this approach for microfabrication of scaffolds for tissue engineering is demonstrated by investigation of the cell response to microstructures with complex three‐dimensional geometry and feature sizes in the range of few micrometers.     

Design of an amperometric biosensor using polypyrrole-microgel composites containing glucose oxidase

A new material consisting of a water-dispersed complex of polypyrrole-polystyrensulfonate (PPy) embedded in polyacrylamide (PA) has been prepared and tested as enzyme immobilizing system for its use in amperometric biosensors. Glucose oxidase (GOx) and the water-dispersed polypyrrole complex were entrapped within polyacrylamide microgels by polymerization of acrylamide in the dispersed phase of concentrated emulsions containing GOx and PPy. Polymerization of the dispersed phase provides microparticles whose size lies between 3.5 and 7 microm. The aim of incorporating polypyrrole into the polyacrylamide microparticles was to facilitate the direct transfer of the electrons released in the enzymatic reaction from the catalytic site to the platinum electrode surface. The conductivity of the microparticles was measured by a four-point probe method and confirmed by the successful anaerobic detection of glucose by the biosensor. Thus, the polyacrylamide-polypyrrole (PAPPy) microparticles combine the conductivity of polypyrrole and the pore size control of polyacrylamide. The effects of the polyacrylamide-polypyrrole ratio and cross-linking on the biosensor response have been investigated, as well as the influence of analytical parameters such as pH and enzymatic loading. The PAPPy biosensor is free of interferences arising from ascorbic and uric acids, which allows its use for quantitative analysis in human blood serum.     

Control of neural stem cell survival by electroactive polymer substrates

Stem cell function is regulated by intrinsic as well as microenvironmental factors, including chemical and mechanical signals. Conducting polymer-based cell culture substrates provide a powerful tool to control both chemical and physical stimuli sensed by stem cells. Here we show that polypyrrole (PPy), a commonly used conducting polymer, can be tailored to modulate survival and maintenance of rat fetal neural stem cells (NSCs). NSCs cultured on PPy substrates containing different counter ions, dodecylbenzenesulfonate (DBS), tosylate (TsO), perchlorate (ClO(4)) and chloride (Cl), showed a distinct correlation between PPy counter ion and cell viability. Specifically, NSC viability was high on PPy(DBS) but low on PPy containing TsO, ClO(4) and Cl. On PPy(DBS), NSC proliferation and differentiation was comparable to standard NSC culture on tissue culture polystyrene. Electrical reduction of PPy(DBS) created a switch for neural stem cell viability, with widespread cell death upon polymer reduction. Coating the PPy(DBS) films with a gel layer composed of a basement membrane matrix efficiently prevented loss of cell viability upon polymer reduction. Here we have defined conditions for the biocompatibility of PPy substrates with NSC culture, critical for the development of devices based on conducting polymers interfacing with NSCs.     

Heterogeneous electron transfer of cytochrome c facilitated by polypyrrole and methylene blue polypyrrole film modified electrodes

Polypyrrole and methylene blue incorporated polypyrrole thin-film modified electrodes were prepared by the electrochemical polymerization method. These modified electrodes may facilitate heterogeneous electron transfer of cytochrome c with high electrocatalytic activity and good stability. Optical thin-layer spectroelectrochemical techniques were used to determine the characteristics of these electrochemical processes such as formal redox potential (E0), electron transfer number (n), and the apparent rate constant (ks.h0).