Analysis of molecular interactions in glucose-aqueous-human mixtard insulin/metformin solutions by volumetric, acoustic properties

• Density, ultrasonic velocity, refractive index, viscosity and surface tension of present systems are measured. • Partial molar and transfer volumes and compressibilities Glc in aqueous-HMI/{HMI + Met} solutions are studied. • Effect of HMI and temperature on partial molar volume and compressibility of glucose are evaluated. • The hydration structure of Glc is affected by Glc-HMI and Glc-Met interactions. • Studies have implication in understanding hydration behavior of glucose and molecular interactions in solutions. In order to understand the molecular interactions between glucose and antidiabetic human mixtard insulin and metformin, the present study reports measured density, ultrasonic velocity, refractive index, viscosity and surface tension of glucose + aqueous-{1 %, 3 %, 5 % and 7 % v/w human mixtard insulin and 7 % v/w human mixtard insulin + 0.05 mol·kg -1 metformin} at different temperatures. Apparent molar volume ( V 2 , ϕ ) and apparent molar isentropic compressibility ( κ S , 2 , ϕ ) of glucose were calculated from density and ultrasonic velocity. Concentration dependence of apparent molar properties was studied and respective partial molar volume ( V 2 o , ϕ ) and compressibility ( κ S , 2 , ϕ 0 ) were determined using Masson's and Gucker's relation respectively. Standard transfer volumes and compressibilities ( Δ t V 2 o , ϕ and Δ t κ S , 2 , ϕ 0 ) of studied solutions were calculated. Transfer properties like viscosity of studied solutions have been measured and viscosity B -coefficients at different temperatures were determined. In addition to this, surface tension and refractive index measurements were carried out. The measured and derived properties have been evaluated in terms of hydration behavior of glucose and molecular interactions of glucose with insulin and metformin. The results of volumetric and acoustic properties indicated the significant effect of HMI and slight effect of metformin on the hydration of glucose at different temperatures. The viscosity study confirms structure making nature of glucose for aqueous-HMI and aqueous-HMI-Met solutions.