紫菌外周捕光天线LH2中的超快能量弛豫

主要用飞秒抽运-探测技术观察了紫细菌Rb. sphaeroides 601外周捕光天线LH2中细菌叶绿素(BChl)之间的能量传递过程. 在783 nm的激光激发B800情况下, 在B800到B850的能量传递之前, 存在一个约0.35 ps的分子内能量重新分布过程; 通过调节激发波长, 清楚地观察到激发态BChl分子的动力学演变过程. 结果表明基态漂白和激发态吸收存在明显的竞争, 同时在818 nm处出现一个鞍点, 说明在B800的激发态和B850的上激子态存在快速、高效的能量传递; B850分子上激子态的激发能将通过内转换向次最低激发态快速弛豫, 并导致最低激发态布局和分子构象变化.     

紫色光合细菌ThermochromatiumTepidum捕光天线复合物2的激发态动力学

Thermochromatium (Tch.) tepidum是一种中等嗜热的紫色光合细菌, 最佳生长温度为48-50 ℃; 其捕光天线复合物2 (LH2)含有非均一性脱辅基蛋白和类胡萝卜素(Car), 且高分辨率晶体结构未知. 我们通过超快光谱研究了分别采用去垢剂n-dodecyl-β-D-maltoside (DDM)和lauryldimethylamine oxide (LDAO)制备的LH2的激发态动力学, 观测到由细菌叶绿素(BChl)的Qy态介导的B800-to-B850单重态能量传递过程(时间尺度~1.2 ps, 用DDM制备的LH2), 以及由类胡萝卜素S2态介导的Car-to-Car和Car-to-BChl 单重态能量传递过程(~100 fs). 结果表明C=C共轭双键数目(NC=C)为11和12的两类Car共处于同一LH2复合物中; 相对于源自其它菌种、构成组分相对简单的LH2, Tch. tepidum的LH2中B800-B850的相对取向有较大差异. 本工作发现LH2中低含量类胡萝卜素组分anhydrorhodovibrin (NC=C=12)起着高效“能量陷阱”的作用, 可能是一种重要的光保护机制; 基于类胡萝卜素的超快谱带位移现象提出(OH-)spirilloxanthin(NC=C=13)距BChl分子可能比其它类胡萝卜素更近. 这些研究结果有助于进一步理解苛刻自然条件下生长的Tch. tepidum的捕光和光保护机制.     

十二烷基硫酸钠诱导Rhodobacter azotoformans外周捕光复合体LH2 B800细菌叶绿素特异性解离

采用吸收光谱法研究了十二烷基硫酸钠(SDS)诱导Rhodobacter azotoformans外周捕光复合体LH2 细菌叶绿素(bacteriochlorophylls, BChls)的解离行为和规律. 结果表明: 室温下, 在10 mmol•L^－1 Tris-HCl (pH 8.0)缓冲液中, 低浓度SDS只诱导LH2中B800 细菌叶绿素解离生成游离BChls, 而B850不受影响; 当浓度达到0.08% (w/V) 时, 能特异性地诱导B800缺失, 其缺失过程和游离BChls的生成过程均符合单指数模型, 且二者的速率常数近似相等. 高浓度SDS能同时诱导B800和B850解离生成游离BChls, 其中B800可发生缺失, 而B850则不完全解离, 解离过程均符合单指数模型; B800对SDS更敏感, 其解离速率常数约是B850的4倍, 游离BChls生成速率常数明显低于B800解离速率常数, 而与B850解离速率常数相接近.     

表面活性剂在逆胶束酶反应系统中的作用机制

随着胶体界面科学与酶技术的发展,逆胶束酶反应系统作为酶等生物分子的高效分离或催化转化的介质体系,为分子生物技术的发展带来了新的机遇.表面活性剂分子特有的两亲性结构,能使微水相以纳米尺寸的水滴形式稳定在非极性有机溶剂中,为酶的活性保持提供了典型的类生物膜微环境.本文对逆胶束酶反应系统原理做简要介绍,并解析表面活性剂的浓度变化及其构型差异在逆胶束酶反应系统中的作用机制,综述近年来表面活性剂在逆胶束酶领域应用的最新成果,同时探讨了新型功能性表面活性剂在胶束酶学中的应用前景和研究趋势.     

超临界CO2中的表面活性剂

介绍了超临界CO2中表面活性剂的结构特征以及聚合物表面活性剂和小分子表面活性剂的研究进展。指出了开发亲CO2表面活性剂的一些基本原则,其中降低表面活性剂在H2O／CO2表面的界面张力和提高表面活性剂的吸附能力比溶解度更为重要。建议加强CO2表面活性剂的研究与开发。     

DMABN在表面活性剂胶束水溶液中的荧光性质

研究了对二甲氨基苯甲腈(DMABN)在各种胶束水溶液中的荧光光谱性质, 发现不同胶束栅栏层区域的不同性质影响了探针的分子内扭转电荷转移(TICT)特性. 对离子型胶束, 头基电场是主要影响因素, 促进了DMABN分子TICT态的形成, 反离子解离度琢越大, 胶束溶液中的Ia/Ib越强. 在非离子表面活性剂胶束中, 聚氧乙烯链环外壳包裹的大量水使其氢键影响明显, 而很短的聚氧乙烯链还可能带来端基氢的氢键作用. 从DMABN的光物理特性看, 欲将胶束作为分散载体利用其TICT态特性, 选择反离子解离度较大的阴离子胶束(例如SDS或SDSO)较好.     

阳离子碳氟表面活性剂研究Ⅰ:水溶液中的胶束特性及生长

利用动态光散射(Dynamic Light Scattering,DLS)、瞬态电双折射(Transient Electric Birefringence,TEB)和粘度测定方法研究了部分氟代阳离子表面活性剂氟代-2-羟基十一烷基二乙羟基甲基氯化铵(diethanolheptadecafluoro-2-undecanol methylammonium chloride,C8F17CH2CH(OH)CH2NCH3(C2H4OH)2Cl,DEFUMACl)水溶液的胶束化特性.结果表明DEFUMACl的临界胶束浓度cmc为3.8 mmol·L-1.稀溶液中随着DEFUMACl浓度的增加或者无机盐NaCl的加入,DEFUMACl胶束由球形向棒状转变,其转变浓度,即第二临界胶束浓度(cmcⅡ)为0.2 mol·L-1;电导测定的反离子(Cl-)结合度为0.72.利用球形和棒状胶束模型确定的DEFUMACl胶束聚集数分别为45和335.     

阳离子碳氟表面活性剂研究I: 水溶液中的胶束特性及生长

利用动态光散射(Dynamic Light Scattering, DLS)、瞬态电双折射(Transient Electric Birefringence, TEB)和粘度测定方法研究了部分氟代阳离子表面活性剂氟代-2-羟基十一烷基二乙羟基甲基氯化铵(diethanolheptadecafluoro-2-undecanol methylammonium chloride, C₈F₁₇CH₂CH(OH)CH₂NCH₃(C₂H₄OH)₂Cl, DEFUMACl)水溶液的胶束化特性. 结果表明: DEFUMACl的临界胶束浓度cmc为3.8 mmol•L^－1. 稀溶液中随着DEFUMACl浓度的增加或者无机盐NaCl的加入, DEFUMACl胶束由球形向棒状转变, 其转变浓度, 即第二临界胶束浓度(cmc_II)为0.2 mol•L^－1; 电导测定的反离子(Cl^－)结合度为0.72. 利用球形和棒状胶束模型确定的DEFUMACl胶束聚集数分别为45和335.     

定量结构-性质相关原理在阴离子表面活性剂临界胶束浓度预测中的应用

利用定量结构-性能相关（QSPR）原理，建立起了8类不同结构，计40个阴离子 表面活性剂临界胶束浓度（cmc）的定量模型。所得到的最佳模型包括：分子总能 量（E_T）、分子生成热（ΔH_f）、分子偶极矩（D）、前线分子轨道能量（E_ (LUMO),E_(HOMO)）及憎水基0级Kier & Hall指数（KHO），计6个描述符，复相关 系数R~2 = 0.9778。     

在超临界CO2聚合反应中应用的表面活性剂的研究

概括了表面活性剂在以超临界CO2 为介质的分散反应和乳化反应中的应用研究进展。重点介绍了几种重要的表面活性剂的结构、机理及应用 ,并指出在应用超临界CO2 技术进行的聚合反应中 ,表面活性剂具有重要的作用及广阔的应用前景。     

Calculation of the excited states properties of LH1 complex of Thermochromatium tepidum

Calculation of the excited states properties of pigment complexes is one of the key problems in the photosynthesis research. The excited states of LH1 complex of Thermochromatium tepidum were studied by means of the high‐precision quantum chemistry methods. The influence of different parameters of the calculation procedure was examined. The optimal scheme of calculation was chosen by comparison of calculated results with the experimental data on absorption, electronic and magnetic circular dichroism spectra. The high importance of the account of the second excited states of bacteriochlorophylls and of site heterogeneity was shown. © 2018 Wiley Periodicals, Inc.     

Carotenoids Do Not Protect Bacteriochlorophylls in Isolated Light-Harvesting LH2 Complexes of Photosynthetic Bacteria from Destructive Interactions with Singlet Oxygen

The effect of singlet oxygen on light-harvesting (LH) complexes has been studied for a number of sulfur (S⁺) and nonsulfur (S⁻) photosynthetic bacteria. The visible/near-IR absorption spectra of the standard LH2 complexes (B800-850) of Allochromatium (Alc.) vinosum (S⁺), Rhodobacter (Rba.) sphaeroides (S⁻), Rhodoblastus (Rbl.) acidophilus (S⁻), and Rhodopseudomonas (Rps.) palustris (S⁻), two types LH2/LH3 (B800-850 and B800-830) of Thiorhodospira (T.) sibirica (S⁺), and an unusual LH2 complex (B800-827) of Marichromatium (Mch.) purpuratum (S⁺) or the LH1 complex from Rhodospirillum (Rsp.) rubrum (S⁻) were measured in aqueous buffer suspensions in the presence of singlet oxygen generated by the illumination of the dye Rose Bengal (RB). The content of carotenoids in the samples was determined using HPLC analysis. The LH2 complex of Alc. vinosum and T. sibirica with a reduced content of carotenoids was obtained from cells grown in the presence of diphenylamine (DPA), and LH complexes were obtained from the carotenoidless mutant of Rba. sphaeroides R26.1 and Rps. rubrum G9. We found that LH2 complexes containing a complete set of carotenoids were quite resistant to the destructive action of singlet oxygen in the case of Rba. sphaeroides and Mch. purpuratum. Complexes of other bacteria were much less stable, which can be judged by a strong irreversible decrease in the bacteriochlorophyll (BChl) absorption bands (at 850 or 830 nm, respectively) for sulfur bacteria and absorption bands (at 850 and 800 nm) for nonsulfur bacteria. Simultaneously, we observe the appearance of the oxidized product 3-acetyl-chlorophyll (AcChl) absorbing near 700 nm. Moreover, a decrease in the amount of carotenoids enhanced the spectral stability to the action of singlet oxygen of the LH2 and LH3 complexes from sulfur bacteria and kept it at the same level as in the control samples for carotenoidless mutants of nonsulfur bacteria. These results are discussed in terms of the current hypothesis on the protective functions of carotenoids in bacterial photosynthesis. We suggest that the ability of carotenoids to quench singlet oxygen (well-established in vitro) is not well realized in photosynthetic bacteria. We compared the oxidation of BChl850 in LH2 complexes of sulfur bacteria under the action of singlet oxygen (in the presence of 50 μM RB) or blue light absorbed by carotenoids. These processes are very similar: {[BChl + (RB or carotenoid) + light] + O₂} → AcChl. We speculate that carotenoids are capable of generating singlet oxygen when illuminated. The mechanism of this process is not yet clear.     

RuH2和RuN2电子组态与光谱性质的从头计算

Using DFT method at B3LYP / 6-311G** level,the possible electronic states of RuH2 and RuN2 have been calculated,including the chemical adsorption and physical adsorption. For the RuH2 cluster,electronic states 3B2 and 5Σ- correspond to the physical adsorption. The RuN2 calculation results were also compared with the experimental values on ruthenium single crystal surfaces. It is found that the single states and the triplet states are in good agreement with the experimental values. For the C∞v symmetry,the calculated frequency of the quintuple state 5Σ- is slightly lower than the experimental value. For the C2v symmetry,the frequencies of the quintuple states are much lower than the experiment value and the 3B2 and 5A1 states are unstable.     

RP—HPLC法测定吡喹酮及其脂质体在小鼠体内的分布

应用RP-HPLC法测定吡喹酮及其脂质体在小鼠体内的分布。用外标定量法测定各组织中的含量,其回收率在96.46～103.13%之间,变异系数小于2.95%。实验结果表明,吡喹酮脂质体较游离吡喹酮在小鼠肝、脾组织内药物总含量明显增高,半衰期延长。     

傅立叶变换红外光谱对琥珀酸-2-乙基己基磺酸钠非极性溶液中 反胶束结构的研究

利用衰减全反射傅立叶变换红外光谱(ATR-FTIR), 对琥珀酸-2-乙基己基磺酸钠(AOT)的反胶束结构进行了研究. 通过对红外光谱进行二维相关分析, 可以分辨出AOT分子在CCl4溶液中具有旁式和反式两种结构, 随着温度的升高, 旁式结构向反式结构转变, 反胶束体系能量降低, 38 ℃时, 反式结构所占比例达到最大值, 此时反胶束具有最大尺寸, 并处于最稳定的能量状态. 随着温度的进一步升高, 反式结构开始向旁式结构转变, 反胶束尺寸变小, 直至最后反胶束被破坏.     

Crystal Structure and Spectroscopic Properties of the Donor-acceptor Complex of 2-Amino-1,3-benzothiazole with Ethyl-5,6-benzocoumarin-3-carboxylate

The donor-acceptor complex derived from 2-amino-1,3-benzothiazole （ABT） and ethyl 5,6-benzocoumarin-3-carboxylate （EBCC） has been synthesized and its crystal structure was determined by single-crystal X-ray diffraction. The crystal belongs to the monoclinic system, space group P21/c, with a = 8.6485（3）, b = 7.7743（3）, c = 29.1963（10） A, β = 92.0460（10）°, Z = 4, Mr = 418.45, V= 1961.79（12） A^3, Dc = 1.417 g/cm^3,μ = 0.199 mm^-1, F（000） = 872, the final R = 0.0350 and wR = 0.1226. The complex is an A…D…D＇…A＇ H-bonded tetramer. The intermolecular N-H…O and N-H…N hydrogen bonds, together with π-π stacking interactions, stabilize the crystal structure by forming a supramolecular architecture. It is found that, in solid state, the fluorescence emission of the complex is quenched significantly while the UV-vis spectrum exhibits a broad band at 346 nm with shoulder, which can be attributed to the donor-acceptor complex formed.     

基于电聚合作用的脂质体免疫传感器检测血液中2,4-二氯苯氧乙酸

利用旋蒸法和挤压法制备脂质体,通过脂质体包埋亚铁氰化钾,利用戊二醛交联2,4-二氯苯氧乙酸(2,4-D)兔抗制成免疫脂质体,制备快速检测血液中2,4-D的夹心型免疫传感器.实验结果表明:2,4-D在75 ng/mL～50 μg/mL浓度范围内呈现良好的线性关系,检测下限达到了36.42 ng/mL.该免疫传感器选择性强...     

Li_2SrSiO_4:Eu~(2+),Nd~(3+)中Eu~(2+)和Nd~(3+)的光谱性质和能量传递

在还原气氛下采用高温固相法制备了Li2SrSiO4:Eu2+,Nd3+发光材料,测量了它们的可见和近红外激发光谱和发射光谱及Eu2+的荧光寿命,研究了Eu2+和Nd3+掺入对其发光性质的影响。结果表明,当Eu2+的浓度为0.01,Nd3+的浓度为0.05时,样品的近红外发光强度最强;Eu2+的发射光谱和Nd3+激发光谱之间的光谱交叠范围较大,Eu2+和Nd3+之间存在着高效无辐射能量传递,能量传递效率约为55.7%,Eu2+的掺入可显著地敏化Nd3+的近红外发光。