Interfacial and Thermodynamic Approach of Surfactants with α-Chymotrypsin and Trypsin: A Comparative Study

The conductivity as well as surface tension measurements have carried out to study the interactions among cetyltrimethyl ammonium bromide (CTAB), sodium dodecyl sulpahe (SDS) with α-chymotrypsin (α-CT) and trypsin in aqueous medium on pH 7.75. The surface parameter i.e., critical micelle concentrations (CMC), the maximum surface excess concentration (Γmax), minimum area per surfactant molecule (Amin) and the surface pressure at CMC (πcmc), and thermodynamic parameters i.e., degree of ionization (α), Gibbs free energy of micellization (ΔG°m), the standard Gibbs energy of adsorption (ΔG°ads), the free energy at air-water interface (ΔGsmim) have been evaluated using surface tension and conductivity measurement. Thermodynamic parameters indicate that enzyme-CTAB/SDS monomeric aggregation started to form micelles at a higher concentration of surfactant to compare with the CMC of pure CTAB/SDS micelles

Interfacial and thermodynamic approach of surfactants with α-chymotrypsin and trypsin: A comparative study

1128-1135This work deals with the interactions among cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS) with α-chymotrypsin (α-CT) and trypsin in aqueous medium on pH 7.75 by conductivity and surface tension measurements. The critical micelle concentrations (CMC), surface parameters i.e., the maximum surface excess concentration (Γmax), minimum area per surfactant molecule (Amin), the surface pressure at CMC (πCMC) and thermodynamic parameters i.e., degree of ionization (α), Gibbs free energy of micellization (ΔG°m), the standard Gibbs energy of adsorption (ΔG°ads), the free energy at air-water interface (ΔGsmim) have been evaluated. The CMC has increased and surface tension of CMC (γCMC) values have decreased (at maximum μL of α-CT and trypsin), significantly in the presence of different μL of the added α-CT and trypsin. In this study, ΔG0ads value is established to be greater than ΔG0m, showing that adsorption is more favored in aqueous surfactants systems. Thermodynamic parameters show that enzyme-CTAB/SDS monomeric aggregation started to form micelles at a higher concentration of surfactant to compare with the CMC of pure CTAB/SDS micelles. It is significant that increasing the μL of α-CT and trypsin results in an increase in the spontaneity CMC on surfactants, α-CT and trypsin have more affinity for SDS compared to CTAB

Mixed Oxime-Functionalized IL/16-<i>s</i>-16 Gemini Surfactants System: Physicochemical Study and Structural Transitions in the Presence of Promethazine as a Potential Chiral Pollutant

The increasing concern about chiral pharmaceutical pollutants is connected to environmental contamination causing both chronic and acute harmful effects on living organisms. The design and application of sustainable surfactants in the remediation of polluted sites require knowledge of partitioning between surfactants and potential pollutants. The interfacial and thermodynamic properties of two gemini surfactants, namely, alkanediyi-α,ω-bis(dimethylhexadecyl ammonium bromide) (16-s-16, where s = 10, 12), were studied in the presence of the inherently biodegradable oxime-functionalized ionic liquid (IL) 4-((hydroxyimino)methyl)-1-(2-(octylamino)-2-oxoethyl)pyridin-1-ium bromide (4-PyC8) in an aqueous solution using surface tension, conductivity, fluorescence, FTIR and 1H NMR spectroscopic techniques. The conductivity, surface tension and fluorescence measurements indicated that the presence of the IL 4-PyC8 resulted in decreasing CMC and facilitated the aggregation process. The various thermodynamic parameters, interfacial properties, aggregation number and Stern–Volmer constant were also evaluated. The IL 4-PyC8-gemini interactions were studied using DLS, FTIR and NMR spectroscopic techniques. The hydrodynamic diameter of the gemini aggregates in the presence of promethazine (PMZ) as a potential chiral pollutant and the IL 4-PyC8 underwent a transition when the drug was added, from large aggregates (270 nm) to small micelles, which supported the gemini:IL 4-PyC8:promethazine interaction. The structural transitions in the presence of promethazine may be used for designing systems that are responsive to changes in size and shape of the aggregates as an analytical signal for selective detection and binding pollutants