Phase partitioning nature, interaction forces and thermodynamic parameters of triton X-100 and bovine serum albumin mixture: impacts of the composition of Na-salt

Abstract

Herein, the assessment of interactions between a non-ionic surfactant (NIS) triton X-100 (TNX-100) and a globular protein bovine serum albumin (BSA) was explored through the determination of clouding nature in aqueous solution of sodium salts (Na-salts). Sodium chloride (NaCl), sodium acetate (NaOAc), sodium carbonate (Na2CO3), sodium oxalate (Na2Oxal), sodium sulphate (Na2SO4), and sodium phosphate (Na3PO4) have been chosen to assess their impacts on the clouding nature of TNX-100 + BSA mixture. The estimated cloud point (CP) values were noticed to be lowered with the enhancement of [Na-salts]. The lessening of CP values has been explained by the salting out effect of anions. The calculated standard Gibbs free energy change () was positive at all examined conditions which illustrates the nonspontaneity of phase change. The standard enthalpy () and entropy () changes exhibited negative values at low contents of aq. Na-salts and positive values at high aq. Na-salts content. These consequences illustrate the presence of electrostatic interactions at low Na-salts concentration and hydrophobic interactions at high Na-salts concentration. Furthermore, enthalpy-entropy parameters were successfully computed and explained with proper clarification.