Synthesis, Structure, Spirocyclization Mechanism, and Glutathione Peroxidase-like Antioxidant Activity of Stable Spirodiazaselenurane and Spirodiazatellurane

The first examples of stable spirodiazaselenurane and spirodiazatellurane were synthesized by oxidative spirocyclization of the corresponding diaryl selenide and telluride and were structurally characterized. X-ray crystal structures of the spirodiazaselenurane and spirodiazatellurane suggest that the structures are distorted trigonal bipyramidal (TBP) with the electronegative nitrogen atoms occupying the apical positions and two carbon atoms and the lone pair of Se/Te occupying the equatorial positions. Interestingly, the spirodiazatellurane underwent spontaneous chiral resolution during crystallization, and the absolute configurations of its enantiomers were confirmed by single-crystal X-ray analyses. A detailed mechanistic study indicates that the cyclization to spirodiazaselenurane and spirodiazatellurane occurs via selenoxide and telluroxide intermediates. The chalcogenoxides cyclize to the corresponding spiro compounds in a stepwise manner via the involvement of hydroxyl chalcogenurane intermediates, and the activation energy for them spirocyclization reaction decreases in the order S > Se > Te. In addition to the synthesis, characterization, and mechanism of cyclization, the glutathione peroxidase (GPx) mimetic activity of the newly synthesized compounds was evaluated. These studies suggest that the tellurium compounds are more effective as GPx mimics than their selenium counterparts due to the fast oxidation of the tellurium center in the presence of peroxide and the involvement of an efficient redox cycle between the telluride and telluroxide intermediate.

Structural studies of model peptides containing beta-, gamma- and delta-amino acids

The crystal structures of five model peptides Piv-Pro-Gly-NHMe (1), Piv-Pro-beta Gly-NHMe (2), Piv-Pro-beta Gly-OMe (3), Piv-Pro-delta Ava-OMe (4) and Boc-Pro-gamma Abu-OH (5) are described (Piv:pivaloyl; NHMe: N-methylamide; beta Gly:beta-glycine; OMe:O-methyl ester; delta Ava:delta-aminovaleric acid; gamma Abu:gamma-aminobutyric acid). A comparison of the structures of peptides 1 and 2 illustrates the dramatic consequences upon backbone homologation in short sequences. 1 adopts a type II beta-turn conformation in the solid state, while in 2, the molecule adopts an open conformation with the beta-residue being fully extended. Piv-Pro-beta Gly-OMe (3), which differs from 2 by replacement of the C-terminal NH group by an O-atom, adopts an almost identical molecular conformation and packing arrangement in the solid state. In peptide 4, the observed conformation resembles that determined for 2 and 3, with the delta Ava residue being fully extended. In peptide 5, the molecule undergoes a chain reversal, revealing a beta-turn mimetic structure stabilized by a C-H center dot center dot center dot O hydrogen bond.

Work/Family Reconciliation: Corporate Management, Family Policies, and Gender Equality in the Finnish Context

Work/family reconciliation is a crucial question for both personal well-being and on societal level for productivity and re-production throughout the Western world. This thesis examines work/family reconciliation on societal and organisational level in the Finnish context. The study is based on an initial framework, developing it further and analysing the results with help of it. The methodology of the study is plural, including varying epistemological emphasis and both quantitative and qualitative methods. Policy analysis from two different sectors is followed by a survey answered by 113 HR-managers, and then, based on quantitative analyses, interviews in four chosen case companies. The central findings of the thesis are that there indeed are written corporate level policies for reconciling work and family in companies operating in Finland, in spite of the strong state level involvement in creating a policy context in work/family reconciliation. Also, the existing policies vary in accessibility and use. The most frequently used work/family policies still are the statutory state level policies for family leave, taking place when a baby is born and during his or her first years. Still, there are new policies arising, such as a nurse for an employee’s child who has fallen ill, that are based on company activity only, which shows in both accessibility and use of the policy. Reasons for developing corporate level work/family policies vary among the so-called pro-active and re-active companies. In general, family law has a substantial effect for developing corporate level policies. Also headquarter gender equality strategies as well as employee demands are important. In regression analyses, it was found that corporate image and importance in recruitment are the foremost reasons for companies to develop policies, not for example the amount of female employees in the company. The reasons for policy development can be summarized into normative pressures, coercive pressures and mimetic pressures, in line with findings from institutional theory. This research, however, includes awareness of different stakeholder interests and recognizes that institutional theory needs to be complemented with notions of gender and family, which seem to play a part in perceived work/family conflict and need for further work/family policies both in managers’ personal lives and on the organisational level. A very central finding, demanding more attention, is the by HR managers perceived change in values towards work and commitment towards organisation at the youngest working generation, Generation Y. This combined with the need for key personnel has brought new challenges to companies especially in knowledge business and will presumably lead to further development of flexible practices in organisations. The accessibility to this flexibility seems to, however, be even more dependent on the specific knowledge and skills of the employee. How this generation will change the organisations remains to be seen in further research.

Matching sender and receiver: poikilothermy and frequency tuning in a tree cricket

Animals communicate in non-ideal and noisy conditions. The primary method they use to improve communication efficiency is sender-receiver matching: the receiver's sensory mechanism filters the impinging signal based on the expected signal. In the context of acoustic communication in crickets, such a match is made in the frequency domain. The males broadcast a mate attraction signal, the calling song, in a narrow frequency band centred on the carrier frequency (CF), and the females are most sensitive to sound close to this frequency. In tree crickets, however, the CF changes with temperature. The mechanisms used by female tree crickets to accommodate this change in CF were investigated at the behavioural and biomechanical level. At the behavioural level, female tree crickets were broadly tuned and responded equally to CFs produced within the naturally occurring range of temperatures (18 to 27 degrees C). To allow such a broad response, however, the transduction mechanisms that convert sound into mechanical and then neural signals must also have a broad response. The tympana of the female tree crickets exhibited a frequency response that was even broader than suggested by the behaviour. Their tympana vibrate with equal amplitude to frequencies spanning nearly an order of magnitude. Such a flat frequency response is unusual in biological systems and cannot be modelled as a simple mechanical system. This feature of the tree cricket auditory system not only has interesting implications for mate choice and species isolation but may also prove exciting for bio-mimetic applications such as the design of miniature low frequency microphones.

Spirodiazaselenuranes: synthesis, structure and antioxidant activity

In this paper, the synthesis, characterization and glutathione peroxidase and peroxynitrite scavenging activities of a series of stable spirodiazaselenuranes are described. The spiro compounds were synthesized in good yields by oxidative cyclization of diaryl selenides bearing amide moieties. All the selenides and spiro derivatives were characterized by H-1, C-13 and Se-77 NMR spectroscopy, mass spectral techniques and the structures of some of the spirodiazaselenuranes were confirmed by single crystal X-ray crystallography. The structures reveal that the selenium atom occupies the center of a distorted trigonal bipyramid core with two nitrogen atoms occupying the apical positions and two carbon atoms and the selenium lone pair occupying the equatorial positions. Mechanistic investigations indicate that the spirocyclization occurs via the formation of selenoxide intermediates. The new compounds were evaluated for their glutathione peroxidase (GPx) mimetic activity by using H2O2 as a substrate and glutathione (GSH) as a co-substrate. It was found that the substituents attached to the nitrogen atom of the selenazole ring have a significant effect on the GPx activity. While the introduction of electron withdrawing groups such as -Cl, -Br etc. to the phenyl ring decreases the activity, the introduction of electron donating groups such as -OH, -OMe significantly enhances the GPx activity of both diaryl selenides and spirodiazaselenuranes. In addition to GPx activity, the selenides and spiro derivatives were studied for their ability to inhibit peroxynitrite (PN)-mediated nitration of bovine serum albumin (BSA) and oxidation of dihydrorhodamine 123. These studies indicate that the diarylselenides effectively inhibit the PN-mediated nitration and oxidation reactions by reacting with PN to produce the corresponding spirodiazaselenuranes.

Substituent Effects on the Stability and Antioxidant Activity of Spirodiazaselenuranes

Spirodiazaselenuranes are structurally interesting compounds and the stability of these compounds depends highly on the nature of the substituents attached to the nitrogen atoms. Aromatic substituents are known to play important roles in stabilizing the Se-N bonds in spiro compounds. In this study, several spirodiazaselenuranes are synthesized by introducing benzylic and aliphatic substituents to understand their effect on the stability of the Se-N bonds and the antioxidant activity. Replacement of phenyl substituent by benzyl/alkyl groups significantly reduces the stability of the spirodiazaselenuranes and slows down the oxidative cyclization process. The selenium centre in the spiro compounds undergoes further oxidation to produce the corresponding selenurane oxides, which are stable at room temperature. Comparison of the glutathione peroxidase (GPx) mimetic activity of the compounds showed that the diaryl selenides having heterocyclic rings are significantly more active due to the facile oxidation of the selenium centre. However, the activity is reduced significantly for compounds having aliphatic substituents. In addition to GPx activity, the compounds also inhibit peroxynitrite-mediated nitration and oxidation reaction of protein and small molecules, respectively. The experimental observations suggest that the antioxidant activity is increased considerably upon substitution of the aromatic group with the benzylic/aliphatic substituents on the nitrogen atoms.

Chemical studies of viral entry mechanisms: I. Hydrophobic protein-lipid interactions during sendai virus membrane fusion. II. Kinetics of bacteriophage λ DNA injection.

Viruses possess very specific methods of targeting and entering cells. These methods would be extremely useful if they could also be applied to drug delivery, but little is known about the molecular mechanisms of the viral entry process. In order to gain further insight into mechanisms of viral entry, chemical and spectroscopic studies in two systems were conducted, examining hydrophobic protein-lipid interactions during Sendai virus membrane fusion, and the kinetics of bacteriophage λ DNA injection.

Sendai virus glycoprotein interactions with target membranes during the early stages of fusion were examined using time-resolved hydrophobic photoaffinity labeling with the lipid-soluble carbene generator3-(trifluoromethyl)-3-(m-^(125 )I] iodophenyl)diazirine (TID). The probe was incorporated in target membranes prior to virus addition and photolysis. During Sendai virus fusion with liposomes composed of cardiolipin (CL) or phosphatidylserine (PS), the viral fusion (F) protein is preferentially labeled at early time points, supporting the hypothesis that hydrophobic interaction of the fusion peptide at the N-terminus of the F_1 subunit with the target membrane is an initiating event in fusion. Correlation of the hydrophobic interactions with independently monitored fusion kinetics further supports this conclusion. Separation of proteins after labeling shows that the F_1 subunit, containing the putative hydrophobic fusion sequence, is exclusively labeled, and that the F_2 subunit does not participate in fusion. Labeling shows temperature and pH dependence consistent with a need for protein conformational mobility and fusion at neutral pH. Higher amounts of labeling during fusion with CL vesicles than during virus-PS vesicle fusion reflects membrane packing regulation of peptide insertion into target membranes. Labeling of the viral hemagglutinin/neuraminidase (HN) at low pH indicates that HN-mediated fusion is triggered by hydrophobic interactions, after titration of acidic amino acids. HN labeling under nonfusogenic conditions reveals that viral binding may involve hydrophobic as well as electrostatic interactions. Controls for diffusional labeling exclude a major contribution from this source. Labeling during reconstituted Sendai virus envelope-liposome fusion shows that functional reconstitution involves protein retention of the ability to undergo hydrophobic interactions.

Examination of Sendai virus fusion with erythrocyte membranes indicates that hydrophobic interactions also trigger fusion between biological membranes, and that HN binding may involve hydrophobic interactions as well. Labeling of the erythrocyte membranes revealed close membrane association of spectrin, which may play a role in regulating membrane fusion. The data show that hydrophobic fusion protein interaction with both artificial and biological membranes is a triggering event in fusion. Correlation of these results with earlier studies of membrane hydration and fusion kinetics provides a more detailed view of the mechanism of fusion.

The kinetics of DNA injection by bacteriophage λ. into liposomes bearing reconstituted receptors were measured using fluorescence spectroscopy. LamB, the bacteriophage receptor, was extracted from bacteria and reconstituted into liposomes by detergent removal dialysis. The DNA binding fluorophore ethidium bromide was encapsulated in the liposomes during dialysis. Enhanced fluorescence of ethidium bromide upon binding to injected DNA was monitored, and showed that injection is a rapid, one-step process. The bimolecular rate law, determined by the method of initial rates, revealed that injection occurs several times faster than indicated by earlier studies employing indirect assays.

It is hoped that these studies will increase the understanding of the mechanisms of virus entry into cells, and to facilitate the development of virus-mimetic drug delivery strategies.

Significados corporificados: uma análise da definição de arte de Arthur C. Danto

O objetivo do presente trabalho é analisar a resposta de Danto ao problema da natureza da arte. Para isso, investigaremos o modo como ele utiliza os experimentos dos indiscerníveis, tanto para objetar as teorias tradicionais da arte como para erigir sua definição; e filosofia da arte, o que pode ser chamado, respectivamente, de tarefa negativa e tarefa positiva do uso do método dos indiscerníveis. A primeira parte desse trabalho se ocupa da tarefa de investigar justamente como os experimentos dos indiscerníveis são usados para objetar as teorias mimética, formalista, expressivista, institucionais, da atitude estética, e, por fim, a teoria da indefinibilidade da arte. A segunda parte trata de demonstrar como Danto, através dos experimentos dos indiscerníveis, extrai as condições necessárias e suficientes de sua definição de arte. A terceira e última parte deste trabalho analisa a relação existente entre a definição da arte e a filosofia da história da arte de Danto, principalmente a tese acerca do fim da arte.

Ler e usar a literatura: alguns artifícios para o envolvimento do leitor

Nesta dissertação investigamos como a ficção envolve o leitor. Para isso, partimos da rejeição a Homero declarada por Calímaco, observando que a suposta diferença entre a literatura preferida pelo público e a literatura preferida pela crítica depende de dois fatores distintos. O primeiro é o simples fato de a crítica ler profissionalmente e o público ler por prazer. O segundo está relacionado à distinção entre recepção e uso da literatura proposta por C.S. Lewis. Na recepção, a obra tende a ser admirada por si; no uso, tende a ser instrumentalizada como suporte para um devaneio em que os desejos do próprio leitor são vicariamente satisfeitos. Observamos que essa devaneio, que Lewis chama de construção egoísta de castelos, e que inclui uma variante mórbida, tem um paralelo na noção girardiana do duplo angélico. Contudo, o devaneio depende da simpatia como definida por Adam Smith, a qual por sua vez depende de certa aprovação moral. Investigamos portanto o tipo de personagem que conquista a aprovação moral do leitor, contrastando os heróis homéricos com os cavaleiros cristãos a fim de verificar como o cristianismo dirige a aprovação moral para as vítimas, fazendo com que os heróis da ficção sejam pessoas perseguidas ou marginalizadas.

A Tenascina-C e a sinalização celular na diferenciação tubulogênica endotelial

A matriz extracelular (MEC) é capaz de modular a adesão celular, induzindo processos de sinalização celular. No estado de aderência intermediária, induzido por proteínas matricelulares, as células tendem a se diferenciar, migrar e proliferar. A tenascina-C é uma proteína matricelular amplamente secretada em gliomas que está envolvida na proliferação e angiogênese tumoral. A MEC de gliomas, possui elevada incorporação de tenascina-C (TN-C), uma glicoproteína matricelular desadesiva que compete com a glicoproteína adesiva fibronectina (FN), desestabilizando os contatos focais e induzindo proliferação celular em gliomas. Neste trabalho nós nos propusemos a investigar o papel da TN-C tumoral no fenótipo angiogênico de células endoteliais. Recentemente em um trabalho publicado pelo nosso grupo observamos que as células endoteliais semeadas sobre matrizes de glioma (U373 MG) aderem menos e são deficientes na capacidade de formar tubos quando comparadas com àquelas plaqueadas sobre MEC de HUVECs. No entanto, neste trabalho, reproduzimos este fenótipo semeando as células endoteliais em suportes de TN-C /FN miméticos da composição da matriz tumoral nativa. Por western blotting, observamos um aumento na fosforilação em treonina 638 da proteína PKCα, um possível sítio inibitório, e um aumento na ativação de PKCδ. O efeito antagônico na regulação dessas isoformas de PKC foi demonstrado quando usamos inibidores seletivos de PKC α e δ e um ativador de PKCα (PMA). Observamos que quando tratamos as HUVECs plaqueadas sobre MEC de U373 com PMA, resgatamos a capacidade dessas células de formar tubos, o pré-tratamento dessas HUVECs com inibidor de PKC δ (rotlerina) resgatou parcialmente a capacidade tubulogênica dessas células. O pré-tratamento das HUVECs que foram semeadas sobre MEC da HUVEC (que formam tubos normalmente) com um inibidor de PKC α (RO320432) levou a diminuição da capacidade tubulogênica. Além disso, esta matriz também induz ativação de ERK e AKT. Investigamos também se o bloqueio dos diferentes domínios da TN-C na matriz derivada de glioma poderia, de alguma forma, reverter o defeito angiogênico das células, propiciado pela interação com a matriz extracelular de gliomas. O pré-tratamento da matriz extracelular de glioma com anticorpos anti-TN-C (contra os domínios FNIII 1-3, 4-5 FNIII e N-terminal) resgatou parcialmente a capacidade das células endoteliais de formar tubos. Nossos dados sugerem que a indução do fenótipo vascular observado em muitos gliomas, com predomínio de vasos mal formados e sub-funcionais, pode ser parcialmente devido ao comprometido da sinalização mediada por PKCs em células endoteliais, bem como do aumento da ativação das vias de ERK e Akt.

模拟生物膜的电化学研究

本文简要评述了生物膜领域的发展过程及研究现状，介绍了关于生物膜的一些基本性质和理论。采用电化学、光谱学以及扫描探针显微镜等方法对支撑双层磷脂膜、磷脂浇铸膜和泡囊等不同的模拟生物膜体系进行了研究。主要结果如下：1．将磷脂与芦丁的混合物滴于玻碳电极表面制备出了嵌有芦丁的磷脂浇铸膜，并以此膜为模拟生物膜的模型研究芦丁在磷脂膜内的电化学行为，以及芦丁对还原型辅酶烟酞胺腺漂吟二核昔酸（NADH）的催化氧化。芦丁与磷脂膜牢固地结合，在pH 7.4的磷酸缓冲溶液中，嵌在磷脂膜内的芦丁显示了准可逆电化学行为，也显示出很好催化氧化NADH的能力，使氧化电流明显增大。同时，与5*10~(-3)mol／L的NADH在裸玻碳电极上的电化学行为相比，其氧化过电位降低了约220 mV。2．在玻碳电极表面制备了嵌有芦丁的磷脂浇铸膜，嵌在磷脂膜内的芦丁显示了准可逆电化学行为。利用这种浇铸膜作为模拟生物膜的模型研究了芦丁对抗坏血酸的催化氧化，磷脂膜一方面与芦丁牢固结合，另一方面为芦丁催化抗坏血酸的氧化提供了理想的生物环境，在pH 7.4的磷酸缓冲溶液中，芦丁能有效地催化氧化抗坏血酸，使抗坏血酸的氧化过电位与裸玻碳电极上的电化学行为相比降低了约100 mV。该修饰磷脂膜和芦丁的玻碳电极对抗坏血酸的测定线性范围为2*10~(-4) mol／L-1.4*10~(-3) mol／L。3．将含有四硫富瓦烯（TTF）和黄嘿吟氧化酶的二甲基二（十二烷基）澳化钱（D DAB）泡囊滴于热解石墨电极表面，制备出一种基于磷脂浇铸膜的黄嘿吟生物传感器。TTF由于其可以有效地转移电子而被选作为电子媒介体，用安培检测的方法研究了工作电位、pH值对黄嘿吟传感器的影响。该传感器的响应时间小于10秒，其检测黄嘿吟线性范围从4*10~(-7)mol／L到2.4*l0~(-6)mol／L，最低检测限为3.2*10~(-7) mol/L。4；将辣根过氧化物酶（HRP）固定在修饰于玻碳电极表面的DDAB浇铸膜内，获得了IIR卫的直接电化学，并以此开发出一种不需媒介体的还02传感器，该传感器对H_2O_2的响应时间约5s，其检测姚。2线性范围从l*10~(-3) mol／L到4*10~(-3)mol／L，同时该传感器也显示出良好的重现性及稳定性。5，利用循环伏安的方法研究了HRP分子在双肉豆范磷脂酰胆碱（DMPC）磷脂膜内的电化学行为，并获得了一对氧化还原峰，说明了DMPC磷脂膜促进了HRP分子的电子传递，同时HRP分子仍保持对H_2O_2的催化生物活J险。UV一vis和CD的检测结果说明HRP分子在与磷脂膜相互作用后，其二级结构没有改变，而三级结构变得松散，这种三级结构的松散可能是使HRP分子的活性基团有所暴露，使得电子传递更容易。AFM实验同样也显示了HRP分子与DMPC磷脂膜间的强烈作用。

模拟生物膜的电化学研究

本文简要介绍了生物膜的组成、结构和一些基本性质，详细描述了各种生物膜模型（支撑磷脂双层膜、非支撑磷脂双层膜、泡囊等等）的制备方法。概要地总结了模拟生物膜的各个领域的研究情况，着重评述了模拟生物膜在电化学、生物传感器、膜片钳、图案化领域的研究进展。采用电化学、各种谱学以及扫描探针显微镜等方法对支撑双层磷脂膜、磷脂浇铸膜等不同的模拟生物膜体系进行了研究。主要结果如下：1．将一种支撑磷脂膜一杂化双层膜（Hbrid bilayerer membrane，HBM）首次用于钙离子与磷脂作用的研究，以Fe（CN）63-为探针，发现钙离子可诱导HBM产生离子通道，且通道的打开与关闭能反复运转，并用STM观察这一现象。2.Ru（bPy）32+的电化学发光法和电催化法被首先用于研究支持脂质双层膜（sBLM）的离子通道行为。高氯酸根可以诱导DODAB（dimethyldioctadecylammonium）产生离子通道行为。离子通道的产生存在着一个闺值，当高氯酸根阴离子的浓度超过0.1μM时离子通道打开，当浓度低于0.1μM时离子通道关闭。当高氯酸根离子浓度高于0.1μM时，被打开的离子通道的数量随着高氯酸根阴离子浓度的增加而增加，在1200μM时达到平衡。离子通道的打开和关闭行为是可逆的。在此基础上，研制了一种用于检测高氯酸根离子的传感器。3，用循环伏安法和交流阻抗法研究了稀土离子与支撑磷脂双层膜的相互作用．稀土离子可以影响支撑磷脂双层膜的结构，使之产生一些小孔，通过这些小孔Fe（CN）63/4可以到达电极表面，显示其电化学行为。Fe（CN）63／4-的氧化还原电流随着稀土离子的浓度的增加而变大，对于E矿＋当浓度达到1．2卿时，电流不再增加。发现三种稀土离子与膜作用的能力如下：Eu3+＞Th3＋＞La3＋。4．铁氰酸根离子通常被用来作离子通道传感器的标记物。在本项工作中，我们首次发现铁氰酸根离子本身也可以作为一种刺激物来控制玻碳电极上DDAB（一种合成磷脂）制备出的支撑双层磷脂膜的通透性。我们利用循环伏安、交流阻抗的方法来研究这种现象。支撑双层磷脂膜与铁氰化物的反应与时间有关。进一步地，我们研制了一种铁氰酸根离子传感器。这种离子通道响应灵敏度较高，它可以检测的铁氰化物的最小浓度为5μM。5．稳定的磷脂浇铸膜是通过把含磷脂的氯仿溶液浇铸到玻碳电极上制备的。我们把一种新的媒介质一去甲肾上腺素嵌入到这种磷脂浇铸膜中。磷脂浇铸膜可以被视为一种生物膜模型。用这个体系对抗坏血酸进行电催化氧化，与在裸玻碳电极上相比，阳极过电位降低了约250 mV。浇铸膜内去甲肾上腺素的电化学行为是受扩散控制的，其扩散系数是1.87×10-5cm2／s。在浓度为0.5-10 mmol／L的范围内，催化电流随抗坏血酸的浓度增大而呈线性增加。在同时含有抗坏血酸和尿酸的溶液中，我们用循环伏安法可以同时侧得两个峰，这两个峰之间的峰位差大约为147mV。6．卵磷脂泡囊和血红蛋白在热解石墨电极上制备的薄膜内，血红蛋白可以实现其直接电化学。血红蛋白在薄膜内表现出薄层电化学行为。其式电位E0在pH 3.5-7.0内随pH值直线变化，斜率为-46.4 mV/pH。磷脂膜内的血红蛋白对H2O2显示了很好的催化还原行为。基于此，研制了无媒介体的H2O2传感器。7．我们合成了一种人工磷脂（二甲基二（十二烷基）澳化钱，DDAB）保护的金纳米粒子。在这些金纳米粒子的促进下，血红蛋白可以表现出直接电子转移（DET）反应，其式电位位于-169mVvs Ag/AgCl参比电极。光谱数据表明电极上的血红蛋白没有变性。这种磷脂保护的金纳米粒子很稳定（至少8个月），它们的平均直径是6.42nm。这是首次应用单层膜保护的纳米粒子去实现蛋白质的直接电化学反应。8．我们在一种新的基底一碳电极上构建了杂化双层膜（HBM）。这是对其它基底上构建的HBM的一种扩展。首先，通过电化学扫描将烷基胺修饰在碳电极表面，使之在电极上形成单层膜。由于烷基链部分向外，因此所构筑的界面是疏水的。然后在碳电极的疏水表面铺展一层磷脂单层膜。所生成的HBM通过电化学和ATR-FTIR技术来表征。根据ATR-FTIR的结果，脂质的有序常数（S）为0.73。这种杂化膜具有磷脂／烷基硫醇HBM的优点。这种HBM在生物传感面具有潜在的应用。

模拟生物膜的电化学研究

介绍了生物膜的组成、结构和一些基本性质，详细描述了各种生物膜模型（支撑磷脂双层膜、非支撑磷脂双层膜、泡囊等等）的制备方法。概要地总结了模拟生物膜的各个领域的研究情况，着重评述了模拟生物膜在电化学、生物传感器、膜片钳、图案化领域的研究进展。采用电化学、各种谱学以及扫描探针显微镜等方法对支撑双层磷脂膜、磷脂浇铸膜等不同的模拟生物膜体系进行了研究。同时还应用分子生物学的方法进行了基因的克隆及其融合蛋白的表达和纯化；另外对生物分子相互结合的动力学问题做了有意义的探索。主要结果如下：1两性霉素在支撑双层磷脂膜上的离子通道行为两性霉素是一种治疗系统性真菌感染的有效药物。通过在电极表面构筑双层磷脂膜作为两性霉素的人工靶向性，用通道离子作为探针分子，检测在两性霉素存在下通道的关闭与打开，建立了两性霉素与支撑双层磷脂膜的相互作用模型。2基于磷脂膜包被的活性肤一微过氧化物酶11的过氧化氢生物传感器首次将活性肤一微过氧化物酶11包被于磷脂膜内制成过氧化氢生物传感器。这一方法使过氧化氢的检侧限大大降低，同时也提高了检测灵敏度。磷脂膜为生物活性分子提供了一个天然的生物相容性的环境，为生物活性分子的有效固定和行使功能提供了良好的场所。3树枝状大分子诱导支撑双层磷脂膜表面的缺陷形成用电化学的方法研究了一系列的不同大小的树枝状大分子与支撑双层磷脂膜的相互作用。研究发现只有较大的分子才能在磷脂膜表面产生缺陷，而且这种诱导产生缺陷的能力还依赖于枝状大分子的结构和表面的电荷密度。4乳链菌肤与支撑双层磷脂膜的相互作用乳链菌肤是一种带正电荷的抗菌肤，它作用于带相反电荷的革兰氏阳性菌的细胞膜表面。通过在电极表面构筑双层磷脂膜来模拟细胞膜表面，使这一复杂的相互作用变得易于用电化学的手段来研究。实验结果表明，乳链菌肤在膜表面形成孔洞是其在膜表面的富集过程，随着乳链菌肤在膜中的浓度的增加，其协同性导致膜表面的孔洞增大，从而最终导致膜的完全被破坏。5电化学结合光谱的方法研究微过氧化物酶11与磷脂膜的相互作用用电化学和光谱的方法研究微过氧化物酶11与阳离子泡囊的相互作用。阳离子泡囊的引入使微过氧化物酶11由在溶液中的无规卷曲向有序的alpha-螺旋转变。这种构型的转变大部分是依靠于短肤分子与膜表面的静电相互作用。6用分子探针指示脂质体诱导的DNA的构型转变用甲基绿分子作为探针分子来检钡（脂质体诱导的DNA分子构型的转变。通过引入探针分子，检测到脂质体诱导DNA分子构型由B到C构型转变。探针分子的引入使DNA分子与脂质体这一复杂的相互作用变得简化。7果蝇热休克蛋白22基因的克隆及其融和蛋白的表达、纯化用PCR方法以果蝇的cDNA为模板扩增出热休克蛋白22基因（hsp22）片段，将其插入原核载体pUCm一T中在大肠杆菌中扩增，再将基因切下插入到原核表达载体pET（28a夕中在大肠杆菌中表达出hsp22:6*His融合蛋白，融合蛋白大小约23KDa，可以用Ni2＋-NTA亲合层析纯化。该蛋白可用来获得hsp22蛋白特异性抗体，从而为检测其在体内的表达以及研究hsp22的功能奠定基础。通过一系列的分子生物学技术获得了融合蛋白，为下一步进行定点突变认为设计所需要的蛋白质序列奠定了基础，为蛋白质折叠和分子识别提供了上游的研究对象和体系。8整体联系的生物分子结合的动力学研究我们讨论了在全局联系的情况下讨论了生物分子表面结合的动力学。对于配体和受体之间相对快速的与没有活化的过程的结合的动力学，具有很好的近似性。当动力学上的驱动力很大的时候，全局联系的观点具有很恰当的适应性。结合的动力学时间常数与温度之间呈“U”字型曲线。在高温的时候时间常数增加是由于在高温下结合变得非常不稳定；而在低温的时候，时间常数随着温度的下降而增加，这是由于陷入了局域的最小值状态。结合的能量地形面的波动也导致动力学随温度的变化而变化。

RESEARCH ON ELECTRICAL-PROPERTIES OF AMPHIPHILIC LIPID-MEMBRANES BY MEANS OF INTERDIGITAL ELECTRODES

Lipids are the main component of all cell membranes and also important mimetic materials. Moreover, it was found recently that they can be used as sensitive membranes for olfactory and taste sensors. Hence the understanding of lipid resistance is important both in sensors and in life sciences. Thirteen lipids were examined by means of interdigital electrodes with narrow gaps of 20-50 mu m, made by IC technology. The membrane lateral resistance in air, resisting electrical voltage, the influence of impurities on resistance and the resistance change in acetic acid vapour are presented for the first time. It is shown that the electrical resistivity for self-assembling lipids depends on their duration of being in an electric field and the content of the conductive impurities. The interdigital electrode is a transducer as well as a powerful tool for researching biomaterials and mimicking materials. The conducting mechanism of lipids is discussed. This method is also suitable for some polymer membranes.

Peeling behavior of a bio-inspired nano-film on a substrate

A peeling model is proposed to analyze the peeling properties of bio-mimetic nano-films using the finite element method (FEM) and theoretical approach. The influences of the nano-film's adhesion length, thickness, elastic modulus, roughness and peeling angle on the peeling force were considered as well as the effect of the viscoelastic behavior. It has been found that the effective adhesion length, at which the peeling force attained maximum, was much smaller than the real length of nano-films; and the shear force dominated in the case of smaller peeling angles, whereas, the normal force dominated at larger peeling angles. The total peeling force decreased with an increasing peeling angle. Two limiting values of the peeling-off force can be found in the viscoelastic model, which corresponds to the smaller and larger loading rate cases. The effects of nano-film thickness and Young's modulus on peeling behaviors were also discussed. The results obtained are helpful for understanding the micro-adhesion mechanisms of biological systems, such as geckos. (C) 2010 Elsevier Ltd. All rights reserved.