Charge characteristics of guar gums on the three-stage interaction mechanism with mucin to improve the mucoadhesion ability

Abstract

The mucoadhesion process is essential for polysaccharide-based nutrient delivery systems. In this study, the intramolecular interactions between mucin and guar gums (GGs) with different charge characteristics going through contact, diffusion, and binding stages were explored. The contact angle analysis was used to characterize the interactions between mucin and GGs at the contact stage. The data of attenuated total reflectance-infrared spectroscopy was calculated to measure the diffusion coefficient (D) of GGs with mucin at the diffusion stage. The results showed that the interactions between the mucin and GGs at the contact and diffusion stages were mainly hydrogen bonding generated by the hydrophilic groups of the polysaccharides and mucin due to the largest contact angle and lowest D value for the neutral guar gum (GG (O)). Fluorescence spectroscopy was carried out to analyze the interactions at the binding stage and found that the interactions were mainly driven by the electrostatic interaction. The results of ΔH°<0 and ΔS°>0 at pH 7.0 indicated the strong electrostatic attraction between the mucin and cationic guar gum (CGG (+)), improving the mucoadhesion ability of the CGG (+); while the electrostatic repulsion weakened the interactions between the mucin and anionic guar gum (AGG (-)). The current discovery of the three-stage interaction mechanism makes it possible to regulate the mucoadhesion ability of the delivery system by altering the polysaccharide charge characteristics.