Equilibrium model for estimating micellar aggregation number from surface equation

López-Cervantes, José L.; Sandoval-Ibarra, Federico D.; Gracia-Fadrique, Jesús

doi:10.1016/j.fluid.2020.112844

Cited by 3 publications

(1 citation statement)

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“…The most accessible experiments aimed to determine micelle aggregation numbers require using a fluorescent probe and a quencher, although other methods including light scattering and small-angle neutron scattering are also occasionally employed. , Several authors have also proposed an alternative method based on surface tension measurements. − The reliability of the results is often dependent on the physicochemical properties of the employed molecules. Additionally, these techniques present some limitations such as the temperature and concentration ranges of the target surfactant.…”

Section: Introductionmentioning

confidence: 99%

Simple ApproximaTion for Aggregation Number Determination by Isothermal Titration Calorimetry: STAND-ITC

et al. 2021

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A new proposal to obtain aggregation numbers from isothermal titration calorimetry dilution experiments is described and tested using dodecyl trimethyl ammonium bromide, dodecyl methylimidazolium chloride, dodecyl methylimidazolium sulfonate, and didecyl methylimidazolium chloride aqueous solutions at different temperatures. The results were compared to those obtained from fluorescence measurements and also with data from the literature. In addition to the aggregation number, the molar free energy to transfer a solute molecule from the aggregate to the bulk solution, the enthalpy corresponding to the formation of the self-assembled suprastructures, the molar heat corresponding to the dilution of monomers and aggregates, and an offset parameter to account for unpredictable external contributions are simultaneously obtained using the same method. The new equations are compared to those obtained from previous proposals, and they are also analyzed in detail to assess the impact of each fitting parameter in the profile of the calorimetric isotherm. This new approach has been implemented in a computational code that automatically determines the fitting parameters as well as the corresponding statistical uncertainties for the large variety of calorimetric profiles that have been tested. Given the high sensitivity of the dilution experiments to the aggregation number for relatively small assemblies, our approach is proposed also to quantify the oligomerization state of biomolecules such as proteins and peptides.

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