Wyniki wyszukiwania - BazTech

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Metody wyznaczania krytycznego stężenia micelarnego związków powierzchniowo czynnych

Grabowska Ola, Dywicki Paweł, Chmurzyński Lech

Wiadomości Chemiczne

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2020

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[Z] 74, 5-6

371--390

EN

Surface active agents, also known as surfactants, are a group of chemical compounds that are used in various products of the chemical industry. These compounds are components of medicines, detergents, motor oils and many others. The multitude of uses of surfactants makes it important to know their aggregation behaviour in solution. There are many methods used to analyse surfactants behaviour in liquid phase. The choice of a particular technique usually depends on the chemical structure of the surfactant. An example of a method that is used in studies of ionic surfactants is conductometry. This technique allows to study the dependence of specific conductivity on surfactant concentration, enabling determination of critical micellar concentration (CMC). Capillary electrophoresis is another example of the method used to determine the critical micellar concentration. It allows to make measurements in conditions where other methods fail, including conductometric method. Surfactant solutions differ in viscosity, which changes with the appearance of micelles in solution. Measurement of marker compound migration time through surfactant solutions of various concentrations allow to determine critical micellar concentration. Isothermal titration calorimetry (ITC) allows to study the thermal effects associated with the aggregation of surfactants into micelles. Based on the energy changes that occur during titration, the critical micellar concentration of surfactant can be precisely determined. ITC is very sensitive method, so basically it can be used to examine all types of surfactants. In addition, the ITC method allows to determine the thermodynamic parameters of the undergoing micellization process. The use of several measuring methods gives a more complete picture of the phenomena occurring in solutions. It allows to understand aggregation process more accurately. Therefore, CMC measurement are often made with the use of several complementary methods.

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Emulsje podwójne i potrójne z modyfikowanymi powierzchniami kropel jako nośniki substancji czynnych

Metera A., Markowska-Radomska A., Dłuska E., Kosicki K., Tudek B., Frączyk T.

Inżynieria i Aparatura Chemiczna

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2017

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Nr 3

92--93

PL

emulsji podwójnych jako potencjalnych nośników substancji czynnych do celowanego uwalniania. Modyfikacja polegała na adsorpcji fizycznej przeciwciał CD15 na powierzchniach kropel, fazy membranowej emulsji W1/O/W2. Stan adsorpcji przeciwciał był oceniony na podstawie analizy efektu cieplnego wszystkich oddziaływań międzycząsteczkowych przy użyciu metody izotermicznego miareczkowania kalorymetrycznego. Wyznaczony efekt cieplny oddziaływań przeciwciała i składników fazy membranowej potwierdził ich adsoipcję na powierzchniach kropel fazy membranowej emulsji W1/O/W2.

EN

The paper presents an investigation into drops’ surface modification of double emulsions as the potential carriers of active agents in targeted therapies. Physical adsorption of CD 15 antibodies on surfaces of membrane phase drops of emulsions W1/O/W2 was evaluated by measuring the heat effect of all molecular interactions using the isothermal titration calorimetry method. The calculated effect of interaction between molecules of antibodies (proteins) and drops of membrane phase ingredients confirmed adsorption of proteins on surfaces of emulsions drops.

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Probing of Cu2+ ions binding to A β (5−16) peptide using ITC measurements and MD simulations

Makowska J., Żmudzińska W., Wyrzykowski D., Brzozowski K., Zblewska H., Chmurzyński L.

TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk

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2016

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Vol. 20, No 4

409--416

EN

It is shown that probably three residues: His6, His14 and His16 in the original sequence A β (1−42) serve as metal-binding sites for Cu2+ions. On the other hand, there is a possibility that only one of them plays a crucial role in the formation of the{A β (1-42)-Cu2+} complex. The isothermal titration calorimetry (ITC) measurements supported by molecular dynamic simulation (MD) with the NMR-derived restrains were used to investigate the interactions of Cu2+ with A β(5-16), a fragment of the A β(1-42) protein, with the following sequence: Ac-Arg-His-Asp-Ser-Gly-Tyr-Glu-Val-His-His-Gln-Lys-NH2, termed HZ1. The conditional thermodynamic parameters suggest that the formation of the Cu2+-HZ1 complex is both an enthalpy and entropy driven process under the experimental conditions. The studies presented here (after comparison with our previous results) show that the affinity of peptides to copper metal ions depends on two factors: the primary structure (amino acid composition) and the shape of the peptide conformation adopted.

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Izotermiczna kalorymetria miareczkowa

Wyrzykowski D.

LAB Laboratoria, Aparatura, Badania

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2012

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R. 17, nr 6

6-11

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A novel method for thermodynamic study on the binding of milk carrier protein of BLG-A with Cr+3

Behbehania G.R., Divsalar A., Saboury A.A.

Polish Journal of Chemical Technology

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2009

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Vol. 11, nr 4

24-29

EN

Thermodynamics of the interaction between Cr3+ with β-lactoglobulin type A (BLG-A) was investigated at pH 7.0 and 37°C by isothermal titration calorimetry. A new method to follow the effect of Cr3+ on the stability of BLG-A was introduced. The new solvation model was used to reproduce the enthalpies of BLG-A+ Cr3+ interactions over the whole range of Cr3+ concentrations. The solvation parameters recovered from the new equation are attributed to the structural change of BLG-A and its biological activity. The results obtained indicate that there is a set of two identical binding sites for Cr3+ ions with positive cooperativity. The association equilibrium constants are 14.39 and 0.49 mM-1 for the first and second binding site, respectively. The enthalpy of binding for one mole of Cr+3 ion to one mole of the binding site on BLG-A (ΔH=104.60 kJ mol-1) is obtained.