二甲酚橙-锆(Ⅳ)配合物光度法测定蛋白质

在酸性溶液中,蛋白质与二甲酚橙-锆(Ⅳ)配合物能够相互作用形成超分子复合物,其最大吸收波长较二甲酚橙-锆(Ⅳ)配合物红移了50 nm。在实验选定最佳条件下,600 nm波长处的吸光度与牛血清白蛋白(BSA)、人血清白蛋白(HAS)均在0.2~16μg/mL范围内呈线性关系,相对标准偏差为0.83%(n=7),检出限为0.1 mg/L。该法灵敏度高,选择性好,用于人血清总蛋白含量的测定,结果满意。     

Mo(Ⅵ)-邻硝基苯基荧光酮配合物光谱探针测定蛋白质

研究了Mo(Ⅵ)-邻硝基苯基荧光酮(o-NPF)配合物与蛋白质的相互作用及光谱性质. 提出了以Mo(Ⅵ)-邻硝基苯基荧光酮配合物作为光谱探针测定微量蛋白质的方法. 结果表明, 在pH为2.2的 HAc-NaAc缓冲介质中, 乳化剂OP存在下, o-NPF-Mo(Ⅵ)在40 ℃加热10 min后与蛋白质形成稳定的复合物, 最大吸收波长红移至587 nm. 蛋白质质量浓度在0～10 mg/L 范围内符合比尔定律, 复合物的表观摩尔吸光系数为3.53×106 L·mol-1·cm-1. 该方法具有很高的灵敏度和选择性, 可直接用于人尿、新生牛血清中蛋白质的测定, 回收率分别为93%和99%.     

铌-铬天青S与牛血清白蛋白结合反应及其应用

探讨了铌-铬天青S配合物与牛血清白蛋白(BSA)结合反应体系.在pH 4.6的邻苯二甲酸氢钾-NaOH(Clark-Lubs)缓冲溶液中,在OP存在下,铌-铬天青S配合物与牛血清白蛋白进一步形成复合物,其最大吸收峰位于595 nm,且随着BSA量的增加,体系在595 nm波长处吸收峰也随着增大.据此建立以铌-铬天青S配合物为光谱探针,分光光度法测定蛋白质含量的新方法.牛血清白蛋白含量在0～0.32 mg/mL的范围内符合比尔定律,摩尔吸光系数ε595为 4.4×105 L·mol-1·cm-1,相关系数为γ=0.9996,生物体内的常见物质基本上不干扰测定,方法可用于人血清蛋白中蛋白质的测定.     

以固绿为试剂流动注射光度法测定血清蛋白质

在pH 1.52的Clark-Lubs缓冲介质中,固绿与血清白蛋白作用,在室温下能迅速结合形成复合物,其最大吸收波长为670 nm,以此反应为基础并结合流动注射技术,提出了血清蛋白质的光度测定法。牛血清白蛋白(BSA)和人血清白蛋白(HAS)质量浓度在5～110 mg·L~(-1)范围内与吸光度成正比,检出限(3S/N)分别为0.52 mg·L~(-1)和0.41 mg·L~(-1)。应用于尿液及人血清中总蛋白的测定,结果与考马斯亮蓝G-250法相符。     

蛋白质-四羧基铜酞菁体系的共振散射行为及其分析应用

在pH 3.0的Clark-Lub's 缓冲溶液中,蛋白质与四羧基铜酞菁(CuPc(COOH)4)作用,使体系的共振光散射增强,在λ=389 nm处光散射强度最大.增强作用的强弱与蛋白质的含量成正比,据此建立了共振光散射测定蛋白质的新方法.此方法对牛血清白蛋白(BSA)、人血清白蛋白(HSA)、免疫球蛋白G(IgG)、鱼精蛋白(Protamine)、血清总蛋白(TP)的测定范围分别为0.05～1.60 mg/L、 0.025～1.60 mg/L、 0～1.45 mg/L、 0.1～1.50 mg/L、 0～1.60 mg/L,相应检出限分别为1.12×10-2 mg/L、 1.11×10-2 mg/L、 1.95×10-2 mg/L、 3.61×10-3 mg/L、 4.34×10-3 mg/L.方法应用于实际人血清样品中总蛋白的测定,结果与考马斯亮蓝法基本一致.     

铬天青S-Cu(Ⅱ)配合物探针吸光光度法测定蛋白质的研究

在pH 5.0 B-R缓冲介质中,蛋白质与铬天青S-Cu（Ⅱ）配合物发生结合反应形成超分子复合物,使体系的最大吸收波长红移了30 nm,由此提出了普通光度法测定蛋白质（BSA）的新方法。最佳条件下,该复合物的最大吸收波长位于620 nm处,表观摩尔吸光系数ε=6.13×105L.mol-1.cm-1,蛋白质（BSA）量在10-60μg/mL范围内遵循比耳定律。方法可直接用于蛋清中蛋白质的测定,回收率为100%-105%。     

维多利亚蓝B-双波长分光光度法测定垃圾渗滤液中十二烷基磺酸钠

在pH 7.3的B-R缓冲溶液中,阴离子表面活性剂十二烷基磺酸钠(SDS)与维多利亚蓝B(VBB)以物质的量比2:1反应生成具有正吸收和负吸收的蓝色离子缔合物,最大正吸收波长为690 nm,最大负吸收波长为615 nm,线性范围分别为0.2～8.2 mg·L-1(正吸收)和0.2～6.8 mg·L-1(负吸收),表观摩尔吸光率为3.48×104L·mol-1·cm-1(正吸收)和2.14×104L·mol-1·cm-1(负吸收),采用双波长叠加测定,灵敏度可达5.60×104L·mol-1·cm-1,据此建立了测定SDS含量的双波长分光光度法.探讨了适宜的反应条件及垃圾渗滤液的预处理方法.该法用于垃圾渗滤液中SDS含量的测定,回收率在98.5 0A～101.0H之间,测定值的相对标准偏差(n=5)在0.8%～1.5%之间.     

偶氮胂Ⅲ-镧(Ⅲ)褪色光度法测定蛋白质

在pH 2.5的酸性介质中, 蛋白质与偶氮胂Ⅲ-镧（Ⅲ）络合物能够相互作用, 形成超分子复合物而使溶液褪色. 最佳条件下, 在650 nm处吸光度的降低值, 与加入的牛血清白蛋白（BSA）或人血清白蛋白（HSA）、溶菌酶（Lyso）质量浓度在一定范围内呈线性关系. BSA在0.5～35 mg/L、 HAS在1～40 mg/L, 溶菌酶（Lyso） 1.7～45 mg/L, 相对标准偏差为0.82% （n=7）. 方法用于人血清总蛋白量的测定.     

探针5-硝基水杨酸同步荧光法测定生物样品中蛋白质

在模拟体液离子强度下,基于5-硝基水杨酸(5-NSA)与人血清白蛋白(HSA)相互作用生成复合物,导致血清白蛋白的内源荧光产生特异性变化,而建立了以5-NSA为分子探针,用固定波长同步荧光光谱分析测定蛋白质的新方法. 体系同步荧光光谱特征及强度受Δλ、反应介质、反应温度等因素的影响. 结果表明,在最佳实验条件下,体系的同步荧光强度(ISF)与人血清白蛋白在3.2×10-8～6.4×10-8 mol/L的质量浓度范围内呈良好的线性关系,检测限为1.7×10-8 mol/L(n=11). 对血清、尿样和唾液样品进行了测定,回收率在99.96%～100.04%之间.     

伊文思蓝光度法测定硫酸阿米卡星的含量

在pH 2.5～6.2的条件下,硫酸阿米卡星(AMK)与伊文思蓝(EB)反应,生成蓝色离子缔合物,最大吸收波长和负吸收波长分别位于678 nm和606 nm,表观摩尔吸光系数(ε)分别为3.02×104L·mol-1·cm-1和4.91×104L·mol-1·cm-1.当用双波长叠加法测定时,ε值可提高到7.95×104L·mol-1·cm-1.该法用于药物中硫酸阿米卡星含量的测定,结果满意.     

Analysis and assessment of the occurrence, the fate and the behavior of nanomaterials in the environment

Nanomaterials have one dimension <100 nm and possess physico-chemical properties dictated by their unusually small size, large surface area, shape and chemical composition. New properties of nanomaterials have boosted their production and industrial applications in many fields (e.g., microelectronics, catalysis, fuel cells, materials science, textiles, biotechnology and medicine). In biomedical fields, nanomaterials are of the appropriate dimensions to interact with biological matter. However, they may also have negative effects on biological systems. Nanotechnology is a major, innovative, scientific and economic growth area, but the increasing production and use of nanomaterials have led to calls for more information regarding the potential impacts that their release may have on human health and the environment.This review addresses analytical approaches for characterization and quantification of nanomaterials in the environment and recent studies on their occurrence, fate and behavior.     

The energy pump and the origin of the non-equilibrium flux of the dynamical systems and the networks

The global stability of dynamical systems and networks is still challenging to study. We developed a landscape and flux framework to explore the global stability. The potential landscape is directly linked to the steady state probability distribution of the non-equilibrium dynamical systems which can be used to study the global stability. The steady state probability flux together with the landscape gradient determines the dynamics of the system. The non-zero probability flux implies the breaking down of the detailed balance which is a quantitative signature of the systems being in non-equilibrium states. We investigated the dynamics of several systems from monostability to limit cycle and explored the microscopic origin of the probability flux. We discovered that the origin of the probability flux is due to the non-equilibrium conditions on the concentrations resulting energy input acting like non-equilibrium pump or battery to the system. Another interesting behavior we uncovered is that the probabilistic flux is closely related to the steady state deterministic chemical flux. For the monostable model of the kinetic cycle, the analytical expression of the probabilistic flux is directly related to the deterministic flux, and the later is directly generated by the chemical potential difference from the adenosine triphosphate (ATP) hydrolysis. For the limit cycle of the reversible Schnakenberg model, we also show that the probabilistic flux is correlated to the chemical driving force, as well as the deterministic effective flux. Furthermore, we study the phase coherence of the stochastic oscillation against the energy pump, and argue that larger non-equilibrium pump results faster flux and higher coherence. This leads to higher robustness of the biological oscillations. We also uncovered how fluctuations influence the coherence of the oscillations in two steps: (1) The mild fluctuations influence the coherence of the system mainly through the probability flux while maintaining the regular landscape topography. (2) The larger fluctuations lead to flat landscape and the complete loss of the stability of the whole system.     

Use of Isotope Effects To Understand the Present and Past of the Atmosphere and Climate and Track the Origin of Life

Stable isotope ratio measurements have been used as a measure of a wide variety of processes, including solar system evolution, geological formational temperatures, tracking of atmospheric gas and aerosol chemical transformation, and is the only means by which past global temperatures may be determined over long time scales. Conventionally, isotope effects derive from differences of isotopically substituted molecules in isotope vibrational energy, bond strength, velocity, gravity, and evaporation/condensation. The variations in isotope ratio, such as ¹⁸O/¹⁶O (δ¹⁸O) and ¹⁷O/¹⁶O (δ¹⁷O) are dependent upon mass differences with δ¹⁷O/δ¹⁸O=0.5, due to the relative mass differences (1 amu vs. 2 amu). Relations that do not follow this are termed mass independent and are the focus of this Minireview. In chemical reactions such as ozone formation, a δ¹⁷O/δ¹⁸O=1 is observed. Physical chemical models capture most parameters but differ in basic approach and are reviewed. The mass independent effect is observed in atmospheric species and used to track their chemistry at the modern and ancient Earth, Mars, and the early solar system (meteorites).     

McBain and the centenary of the micelle

In 1913, J.W. McBain introduced the word “micelle” into surface and colloid chemistry in the context of the association of surfactant molecules in aqueous solution. This article gives a biographic account of McBain, and reviews the early work on micellar aggregation, leading up to the pioneering ideas of G.S. Hartley who introduced the first model of the spherical micelle that we would recognise today.     

New study of the stability and of the spectroscopy of the molecular anions NCO- and CNO-

Using highly correlated wave functions, the ground and the low lying excited states of the molecular NCO(-) and CNO(-) anions have been reinvestigated. The stability of the electronic ground state of the two isomers with respect to dissociation and to electron detachment has been checked along the isomerization pathway. The regions of stability of the excited electronic states have been analyzed and identified and it is shown that only the ground state is stable and the corresponding potential energy surface presents three equilibrium positions. The rovibronic spectroscopy of the X (1)Σ(+) state of both NCO(-) and CNO(-) isomers has been determined by a variational approach leading to remarkable agreement with experimental data.     

Influence of the molecular structure and the nature of the solvent on the absorption and fluorescence characteristics of rhodamines

A study of the equilibrium of the molecular forms of rhodamine 19 in aqueous and ethanolic solution is carried out by determining the absorption and fluorescence characteristics of the zwitterionic and the cationic forms of the dye. The optical properties of rhodamine 19 are compared with those obtained for rhodamine 6G and also with those previously reported for rhodamine 3B and for the molecular forms of rhodamine B in water and ethanol. Different aspects of the molecular structure of the rhodamines and solvent effects are discussed, as well as their influence on the photophysical properties of the rhodamines. The aggregation of the molecular forms of rhodamine 19 is also studied in water and ethanol.     

Synthesis and pharmacological effects of the enantiomers of the N-phenethyl analogues of the ortho and para e- and f-oxide-bridged phenylmorphans

The N-phenethyl analogues of (1R*,4aR*,9aS*)-2-phenethyl-1,3,4,9a-tetrahydro-2H-1,4a-propanobenzofuro[2,3-c]pyridin-6-ol and 8-ol and (1R*,4aR*,9aR*)-2-phenethyl-1,3,4,9a-tetrahydro-2H-1,4a-propanobenzofuro[2.3-c]pyridin-6-ol and 8-ol, the ortho- (43) and para-hydroxy e- (20), and f-oxide-bridged 5-phenylmorphans (53 and 26) were prepared in racemic and enantiomerically pure forms from a common precursor, the quaternary salt 12. Optical resolutions were accomplished by salt formation with suitable enantiomerically pure chiral acids or by preparative HPLC on a chiral support. The N-phenethyl (-)- para-e enantiomer (1S,4aS,9aR-(-)-20) was found to be a mu-opioid agonist with morphine-like antinociceptive activity in a mouse assay. In contrast, the N-phenethyl (-)-ortho-f enantiomer (1R,4aR,9aR-(-)-53) had good affinity for the mu-opioid receptor (K(i) = 7 nM) and was found to be a mu-antagonist both in the [(35)S]GTP-gamma-S assay and in vivo. The molecular structures of these rigid enantiomers were energy minimized with density functional theory at the level B3LYP/6-31G* level, and then overlaid on a known potent mu-agonist. This superposition study suggests that the agonist activity of the oxide-bridged 5-phenylmorphans can be attributed to formation of a seven membered ring that is hypothesized to facilitate a proton transfer from the protonated nitrogen to a proton acceptor in the mu-opioid receptor.     

Isolation and identification of the anti-isohumulones and the anti-acetylhumulinic acids

The anti-isohumulones [5-(3-methylbutanoyl)-2-(3-methylbut-2-enyl)-4-hydroxy-4-(4-methylpent-3-enoyl)-cyclopentane-1,3-diones] and the anti-acetylhumulinic acids [5-(3-methylbutanoyl)-2-(3-methylbut-2-enyl)-4-ethanoyl-4-hydroxy-cyclopentane 1,3-diones] have been isolated from an isomerisation reaction mixture of humulone [2-(3-methylbutanoyl)-4,6-di(3-methylbut-2-enyl)-6-hydroxy-cyclohexane-l,3,5-trione] by counter-current distribution and identified by spectroscopic techniques. The formation mechanism is presented and the stereochemical consequences are discussed. The anti-isohumulones are the most bitter hop compounds presently known.