Enhanced stabilization of the Tobacco mosaic virus using protic ionic liquids

We report on the use of protic ionic liquids, pILs, as solvents for the solubilisation and stabilization of viruses. We show that the shelf life of the pIL stabilized tobacco mosaic virus is significantly enhanced when compared to traditional phosphate buffer. This has new opportunities for the preparation, characterization and storage of viruses and virus based technologies.     

沥青质分散剂对沥青质的稳定及缔合的影响

采用紫外－可见光谱法研究了沥青质分散剂对甲苯－正庚烷－沥青质体系中沥青质的稳定作用,通过黏度法考察了沥青质分散剂对沥青质溶液中胶束缔合度的影响。结果表明,十二醇（DAL）、十二烷基苯磺酸（DBSA）、十二烷基苯酚（DP）对沥青质都有一定的稳定作用。三种沥青质分散剂的稳定作用顺序为DBSA>DP>DAL。DAL、DP及DBSA浓度较低时（1%）对沥青质甲苯溶液黏度的影响规律相似,推迟了黏度迅速增加的拐点,即可以抑制沥青质胶束的缔合。DBSA浓度较大时,沥青质胶束没有明显的聚并,同时使得沥青质溶液的相对黏度增加明显。三种沥青质分散剂都能显著降低胶束的聚集数;三种沥青质分散剂抑制沥青质胶团聚并强弱顺序为：DBSA>DP>DAL。这与其头部官能团的酸性顺序一致。     

Effect of compressed CO2 on the critical micelle concentration and aggregation number of AOT reverse micelles in isooctane

The effect of compressed CO2 on the critical micelle concentration (cmc) and aggregation number of sodium bis-2-ethylhexylsulfosuccinate (AOT) reverse micelles in isooctane solution was studied by UV/Vis and fluorescence spectroscopy methods in the temperature range of 303.2-318.2 K and at different pressures or mole fractions of CO2 (X(CO2)). The capacity of the reverse micelles to solubilize water was also determined by direct observation. The standard Gibbs free energy (DeltaGo(m)), standard enthalpy (DeltaHo(m)), and standard entropy (DeltaSo(m)) for the formation of the reverse micelles were calculated by using the cmc data determined. It was discovered that the cmc versus X(CO2) curve and the DeltaGo(m) versus X(CO2) curve for a fixed temperature have a minimum, and the aggregation number and water-solubilization capacity of the reverse micelles reach a maximum at the X(CO2) value corresponding to that minimum. These results indicate that CO2 at a suitable concentration favors the formation of and can stabilize AOT reverse micelles. A detailed thermodynamic study showed that the driving force for the formation of the reverse micelles is entropy.     

Surfactant-induced amorphous aggregation of tobacco mosaic virus coat protein: a physical methods approach

The interactions of non-ionic surfactant Triton X-100 and the coat protein of tobacco mosaic virus, which is an established model for both ordered and non-ordered protein aggregation, were studied using turbidimetry, differential scanning calorimetry, isothermal titration calorimetry, and dynamic light scattering. It was found that at the critical aggregation concentration (equal to critical micelle concentration) of 138 x 10(-6) M, Triton X-100 induces partial denaturation of tobacco mosaic virus coat protein molecules followed by protein amorphous aggregation. Protein aggregation has profound ionic strength dependence and proceeds due to hydrophobic sticking of surfactant-protein complexes (start aggregates) with initial radii of 46 nm. It has been suggested that the anionic surfactant sodium dodecyl sulfate forms mixed micelles with Triton X-100 and therefore reverses protein amorphous aggregation with release of protein molecules from the amorphous aggregates. A stoichiometric ratio of 5 was found for Triton X-100-sodium dodecyl sulfate interactions.     

Effect of interfacial interaction on the cross-sectional morphology of tobacco mosaic virus using GISAXS

We have investigated the effect of the interfacial interaction on the cross-sectional morphology of the tobacco mosaic virus (TMV) in solution and on two types of solid substrates, SiOx (polar) on Si(100) and polystyrene film (nonpolar) on Si(100), using small-angle X-ray scattering (SAXS) and grazing incidence small-angle X-ray scattering (GISAXS), respectively. Results reveal that the flexible chains at the outer surface of TMV either expand or contract depending on the nature of the substrate. Although the unfavorable interaction between the TMV and the PS causes a minimal effect, the stronger attractive interaction between the outer protein surface of TMV and the SiOx substrate induces pronounced deformation of its cross-sectional morphology.     

Precipitation and recrystallization of uniform CuCl particles formed by aggregation of nanosize precursors

Uniform, spherical CuCl particles were obtained by mixing aqueous solutions of CuCl ₂ and ascorbic acid in the presence of polyvinylpyrrolidone (PVP) as dispersing agent. The size and the uniformity of the resulting particles depended on the volume ratio of the reactant solutions, their concentrations, the distribution of the stabilizers, and the mixing method. The single jet precipitation yielded large spheres of broad size distributions, while the particles obtained by the double jet technique were rather uniform in size. The final colloidal CuCl particles were formed by the aggregation of nanocrystals, initially generated in the system. Depending on the pH of the reaction mixture, these particles slowly change to large CuCl crystals on aging in the mother liquor.     

Photochemistry of tobacco mosaic virus RNA. Effect of HCN

Abstract— In attempting to sort out possible mechanisms of photoreactivation of tobacco mosaic virus RNA (TMV-RNA) inactivated by ultraviolet radiation (u.v.) in buffer of ionic strength 0.25, we have investigated the effect of HCN on the quantum yield for u.v. inactivation of TMV-RNA and on the percent photoreactivation of inactivated TMV-RNA. Some photo-products produced by irradiation of model substances, polyuridylic acid (poly U) and polycytidylic acid (poly C), in the presence of HCN have also been studied. The ratio of the quantum yield for inactivation of TMV-RNA in the presence of HCN to that in the absence of HCN is 1.5, under non-photoreactivating conditions. By comparison, the ratio of the initial rates of loss of uracil residues in poly U under comparable conditions is 1.6; by contrast, the rate of loss of cytosine residues in poly C is unaffected by HCN. This similarity of ratios between poly U and TMV-RNA suggests that two of the mechanisms of u.v. inactivation of TMV-RNA at high ionic strength are akin to known reactions of uracil residues in poly U, i.e. hydrate and dimer formation. The photohydration reaction in poly U, as measured by the heat reversal of hydrated residues to uracil residues, is almost abolished by HCN, and the rate of dimerization, as measured by the appearance of dimer containing oligonucleotides following enzymatic hydrolysis of irradiated poly U, is reduced to half by HCN. HCN does not affect the rate of hydration of cytosine residues in poly C. Since photoreactivation of RNA inactivated in presence of HCN is only 60 per cent of that in absence of HCN it is suggested that uracil dimers are somehow involved in photoreactivation of TMV-RNA inactivated at high ionic strength.     

Quantum-chemical analysis of the CuCl2 molecule

This paper reports on quantum-chemical analysis of the linear structure of CuCl₂ by Hartree-Fock (HF) and density functional theory (DFT) methods and also by time-dependent HF (TD HF) and DFT (TD DFT) techniques. Using pure DFT exchange correlation functional (B3LYP) yields the best agreement with the experimental electronic spectra of CuCl₂. In this case, the odd electron is delocalized over the molecule, spin density on copper being 0.27. The ground state of the CuCl₂ molecule is ²Π_g with linear geometry.     

Study of CuCl2 Supported on SiO2 and Al2O3

The nature and stability of surface species of CuCl₂ supported on α-Al₂O₃, γ-Al₂O₃, and SiO₂ were investigated by using X-ray diffraction techniques and reflectance spectroscopy. No specific chemical interaction of CuCl₂ is observed on an inert α-Al₂O₃ support, as opposed to hydrated carriers as SiO₂ and γ-Al₂O₃. On these supports the coordination sphere of Cu²⁺ consists of surface groups (OH^? or O^? at drying and activation, resp.), H₂O and Cl^?, with the H₂O ligands decreasing in concentration in the process of impregnation, drying and calcination. γ-Al₂O₃ samples, calcined at 400°C, show γ-Cu₂(OH)₃Cl as opposed to CuAl₂O₄ at higher temperatures. The absence of Cu₂(OH)₃Cl on SiO₂-supported samples is related to the acid-base characteristics of the carriers. The various supports can be arranged in the following order of stability of the complexes formed: γ-Al₂O₃ > SiO₂ ? -Al₂O₃.     

Dual-surface modification of the tobacco mosaic virus

The protein shell of the tobacco mosaic virus (TMV) provides a robust and practical tubelike scaffold for the preparation of nanoscale materials. To expand the range of applications for which the capsid can be used, two synthetic strategies have been developed for the attachment of new functionality to either the exterior or the interior surface of the virus. The first of these is accomplished using a highly efficient diazonium coupling/oxime formation sequence, which installs >2000 copies of a material component on the capsid exterior. Alternatively, the inner cavity of the tube can be modified by attaching amines to glutamic acid side chains through a carbodiimide coupling reaction. Both of these reactions have been demonstrated for a series of substrates, including biotin, chromophores, and crown ethers. Through the attachment of PEG polymers to the capsid exterior, organic-soluble TMV rods have been prepared. Finally, the orthogonality of these reactions has been demonstrated by installing different functional groups on the exterior and interior surfaces of the same capsid assemblies.     

DTA analysis of the system CuCl2-KCl

Mixtures of CuCl₂ and KCl in molar ratios of Cu to K of from 0.5 to 1.0 were heated at 473 K in an air atmosphere, and then subjected to DTA analysis in the temperature range 293–773 K. A number of endothermic processes were observed, the extents of these depending on the molar ratio of Cu to K in the mixture.

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Zusammenfassung DTA-Untersuchungen haben ergeben, daß in Mischungen von CuCl₂ und KCl mit molaren Cu/K-Verhältnissen von 0,5–1,0 nach Erhitzen in Luft bei 473 K im Temperaturbereich von 293 bis 773 K eine Reihe von endothermen Prozessen verlaufen. Das Ausmaß dieser Prozesse hängt vom Cu/K-Verhältnis der Gemische ab.

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( 0,5 1,0) 293–773 , , .

     

Effect of sucrose on BSA denatured aggregation at high concentration studied by the iso-conversional method and the master plots method

The kinetics of protein thermal transition is of a significant interest from the standpoint of medical treatment. The effect of sucrose (0–15 mass%) on bovine serum albumin denatured aggregation kinetics at high concentration was studied by the iso-conversional method and the master plots method using differential scanning calorimetry. The observed aggregation was irreversible and conformed to the simple order reaction. The denaturation temperature (T _m), the kinetic triplets all increased as the sucrose concentration increased, which indicated the remarkable stabilization effect of sucrose. The study purpose is to provide new opportunities in exploring aggregation kinetics mechanisms in the presence of additive.     

Solvent effect on CuCl2-pyridine derivative complexes: UV-VIS and E.S.R. study of the CuCl2-2,4-dimethylpyridine-solvent systems

Summary The electronic (400–800 nm; 298.2 K) and E.S.R. spectra (298 K; 77 K) have been measured for CuCl₂-2,4-dimethylpyridine(2,4-Me ₂ py)-solvent systems (solvents: aliphatic and aromatic hydrocarbons, carbon tetrachloride, chloroform, 1,1,2,2-tetrachloroethane). In all the media CuCl₂ forms electrically neutral strongly distorted six-coordinated complexes, the extent of tetragonality being greater than for analogous complexes with non-a-substituted pyridines. In contrast to aliphatic and aromatic hydrocarbons protic solvents and, unexpectedly, aprotic carbon tetrachloride solvate the CuCl₂-Me ₂ py complex comparatively strongly, most probably through interactions with the chlorine ligand. The results for 2,4-Me ₂ py were compared with those for pyridine, 4-ethylpyridine and isoquinoline and discussed in terms of steric effects on solvation. In particular,a-substitution seems to hinder the solvation of the complex by the amine.

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Lösungsmitteleinfluß auf den Koordinationszustand des CuCl₂ in Lösungen. Elektronen- und EPR-Spektren der CuCl₂-2,4-Dimethylpyridin-nichtwäßrigen Lösungsmittel-Systeme

Zusammenfassung Es wurden die Absorptions-Elektronenspektren (400–800 nm; 298.2 K) und EPR-Spektren (298 K; 77 K) verschiedener CuCl₂-2,4-Dimethylpyridin(2,4-Me ₂ py)-Lösungsmittel(L)-Systeme gemessen und mit analogen CuCl₂-Pyridinbasen-L-Systemen verglichen (L=aliphatische und aromatische Kohlenwasserstoffe, Chloroform, Tetrachloromethan, 1,1,2,2-Tetrachlorethylen). In allen Lösungen bildet CuCl₂ mit Pyridinbasen neutrale, stark verzerrt oktaedrische monomere Komplexe. Die Verzerrung nimmt mita-Substitution zu. Bemerkenswert ist, daß CCl₄ einen Mediumeffekt zeigt, der demjenigen der protischen Lösungsmitteln ähnlich ist; er solvatiert die Komplexe verhältnismäßig stark, möglicherweise an den Chloridliganden. Die Komplexe vona-substituierten Phyridinbasen sind gegenüber Solvatation weniger empfindlich als die übrigen.

     

CuCl2对聚乙二醇（PEG）的构象和结晶的影响

用傅里叶变换红外光谱法(FT-IR)、差示扫描量热法(DSC)、广角 X射线衍射法(WAXD)研究了少量过渡金属盐氯化铜(CuCl2)对聚乙二醇(PEG)构象和结晶行为的影响. Cu2＋与PEG分子链中的氧原子有配位键生成, 通过溶液电导率的测定, 发现一个Cu2＋大约与3个PEG链节单元形成配位结构, 从而使PEG的构象和结晶行为发生变化, 随着体系中CuCl2含量的增加, PEG分子链中OC—CO旁式构象相对反式构象含量逐渐增加, 在CuCl2含量(w)为7%左右时达到极大值, 在CuCl2含量(w)为9%时, 反而是反式构象相对旁式构象含量多些. 混合物中PEG的结晶度随着体系中CuCl2含量的增加逐渐降低, 含量(w)为9%时, 又有所提高.     

The influence of the salt concentration on the aggregation behavior of viscoelastic detergents

The influence of excess NaCl on the properties of viscoelastic detergent solutions of Cetypyridiniumsalicylate (CPySal) has been studied by static and dynamic light scattering, electric birefringence and rheological measurements. It is obeserved that the rodlike micelles of length L which are present in these solutions and which are responsible for their elastic properties grow in length with the increase of the NaCl concentration. As long as the rods are shorter than their mean distance, their length can be determined from the rheological and electric birefringence measurements. For very small shear fields these solutions behave as Newtonian fluids. The viscosity of the solution increases strongly when the rods begin to overlap. Solutions with overlapping rods are elastic. It is postulated from the results that the cmc_II (the critical concentration above which rods are present) and the length L of the rods are partially determined by the intermicellar interaction energy. It is furthermore postulated that this intermicellar interaction energy has an influence on the polydispersity of the rods and seems to make the rods relatively monodisperse.     

Al和CuCl2溶液反应机理的实验探究

铝与氯化铜反应的现象是铝丝表面析出的铜呈海绵状,同时产生了大量的氢气,为此,师生一起对铝和氯化铜溶液反应的机理进行实验探究。