Interaction Behavior of N-Lauroyl Sarcosine Sodium Salt (NLSS) and Benzethonium Chloride (BC) in Aqueous Human Serum Albumin (HSA) at Different Temperatures: A Volumetric and Acoustic Study

Abstract

Density and speed of sound values of N-lauroyl sarcosine sodium salt (NLSS) and benzethonium chloride (BC) in mixed aqueous mixtures of human serum albumin (HSA) at three equidistant temperatures (298.15, 308.15, and 318.15 K) have been measured. Using density and speed of sound data, various thermodynamic and acoustic parameters like apparent molar volumes (V ϕ), partial molar volumes (V ϕ °), partial molar volumes of transfer (Δtr V ϕ °), dependence of partial molar volume on temperature, Helper’s constant, apparent molar isentropic compressibility (K ϕ,S), partial molar isentropic compressibility (K ϕ,S °), partial molar isentropic compressibility of transfer (Δtr K ϕ,S °), hydration number, and pair–triplet interaction coefficients have been determined. The cosphere overlap model was used to analyze several kinds of molecular interactions present in the studied systems, and it was found that two types of interactions were present in the studied system, i.e., ion–hydrophilic and hydrophilic–hydrophilic interactions. Negative values of Helper’s constant revealed that both NLSS and BC behave as structure breakers.