Impact of Ultrasound on the Physical Properties and Interaction of Chitosan–Sodium Alginate

Abstract

The aim of the study was to investigate the impact of ultrasound on the physical properties and interaction of chitosan (CHI)-sodium alginate (ALG) by rheological behavior, dynamic light scattering, and isothermal titration calorimetry (ITC). The CHI–ALG solutions were treated with ultrasound at 50°C, 0.45 W/cm² and different frequencies (28 and 40 kHz) for different times (10 and 30 minutes). Ultrasonic treatment effectively decreased the viscosity and consistency coefficient and increased the flow behavior index of the CHI–ALG solution, leading to its change in the flow behavior from pseudoplastic to near-Newtonian behavior. It was interesting to find that ultrasonic treatment slightly decreased G′ and increased G″, which indicated that ultrasound strengthened the fluid character and weakened the solid nature of CHI–ALG. The particle size distribution of ultrasonic treated CHI–ALG solutions was shifted to lower values compared to the untreated sample. ITC analysis showed that there was an increase in the affinity constant. However, thermodynamic parameters enthalpy (ΔH), entropy (ΔS), and Gibbs free energy change (ΔG) were not obviously affected by ultrasonication. These results suggested that ultrasonic treatment of CHI–ALG would affect the molecular diffusion by changing the wall material nature and further impact the immobilized enzyme activity.

GRAPHICAL ABSTRACT

Keywords:

• Chitosan-sodium alginate
• interaction
• physical properties
• ultrasound