Chitosan solubility in organic acid solutions under ultrasonication: A comparative perspective

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Materials Engineering

Background:

• Chitosan, a chitin-derived biopolymer, possesses significant biomedical and environmental potential.
• Poor solubility in neutral solvents currently limits chitosan's widespread application.
• Developing effective solubilization methods is crucial for unlocking chitosan's full capabilities.

Purpose of the Study:

• To systematically compare the solubility and stability of chitosan in acetic acid (AA), citric acid (CA), and glutamic acid (GA).
• To investigate the impact of ultrasonication and varying acid concentrations on chitosan dissolution.
• To establish mechanistic links between acid chemistry, ultrasonic treatment, and chitosan solubility.

Main Methods:

• Chitosan solubility and stability were evaluated in 0.2-1.0% v/v AA, CA, and GA under ultrasonication.
• Techniques included FTIR, UV-Vis spectroscopy, pH, zeta potential, XRD, SEM, and TGA.
• Comparative analysis focused on dissolution efficiency, colloidal stability, and structural integrity.

Main Results:

• Acetic acid (AA) demonstrated the highest solubilization efficiency, producing homogeneous, transparent chitosan dispersions.
• Citric acid (CA) provided superior long-term stability but led to partial ionic crosslinking at higher concentrations.
• Glutamic acid (GA) showed limited effectiveness due to aggregation, likely related to its zwitterionic nature. Ultrasonication significantly improved dispersion and homogeneity across all acid systems, especially AA.
• This study is the first to directly compare chitosan solubility in mono-, tri-, and zwitterionic acids under identical sonication conditions.

Conclusions:

• Acetic acid (AA) is the most effective medium for ultrasonically assisted chitosan solubilization, offering enhanced dispersion and homogeneity.
• The choice of organic acid significantly influences chitosan's solubility, stability, and structural integrity, with implications for formulation design.
• Findings provide a practical framework for developing tailored chitosan formulations for drug delivery, antimicrobial coatings, and environmental adsorbents.