Adsorption kinetics of BSA at air–sugar solution interfaces as affected by sugar type and concentration

Abstract

The influence of glucose, sucrose and fructose at concentrations ranging from 0 to 40 wt.% on the adsorption kinetics of bovine serum albumin (BSA) at air–aqueous solution interfaces at 20 °C was measured using drop shape analysis. The rate of adsorption of proteins decreased in the presence of sugars. The diffusion coefficient of BSA in 40 wt.% sucrose solutions, calculated from the initial period of protein adsorption, was two orders of magnitude lower than the diffusion coefficient of BSA dissolved in pure water. The decrease of the diffusion coefficient with sugar concentration (δ D eff/δ c sugar) was appreciably higher at low sugar concentrations (<10 wt.%). Diffusion coefficients in the presence of sucrose were smaller than in the presence of glucose or fructose. Results were attributed to an increase in solution viscosity, preferential interactions of sugars with protein surfaces and an increased hydrophilicity of protein surfaces due to preferential hydration.