Strong Hydrophobic Interaction of High Molecular Weight Chitosan in Aqueous Solution

Chitosan is a versatile bioactive polysaccharide in various industries, such as pharmaceuticals and environmental applications, owing to its abundance, biodegradability, biocompatibility, and antibacterial properties. To effectively harness its potential for various purposes, it is crucial to understand the mechanisms of its interaction in water. This study investigates the interactions between high molecular weight (HMW, >150 kDa) chitosan and four different functionalized self-assembled monolayers (SAMs) at three different pHs (3.0, 6.5, and 8.5) using a surface forces apparatus (SFA). We report that HMW chitosan exhibits the strongest adhesion to methyl-terminated SAM (CH3–SAM) at all pHs, showing potential for strong hydrophobic interactions against other molecules containing hydrophobic moieties. Noting that hydrogen bonding has been considered the dominating interaction mechanism of chitosan, the consequence of this study provides valuable insights into its applications in developing chitosan-based eco-friendly materials.