Controlling antimicrobial activity and drug loading capacity of chitosan-based layer-by-layer films

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Surface Science

Background:

• Layer-by-layer (LbL) assembly is a versatile technique for fabricating thin films.
• Chitosan (CHI) and hyaluronic acid (HA) are biocompatible polysaccharides with tunable properties.
• Controlling LbL film characteristics is crucial for diverse applications.

Purpose of the Study:

• To investigate the influence of chitosan degree of deacetylation (DD¯) and solution pH on HA/CHI LbL film properties.
• To explore the potential of these tailored films for antimicrobial activity and controlled dye release.

Main Methods:

• Fabrication of HA/CHI LbL films using chitosans with varying DD¯ (≈85%, 65%, 40%) and molecular weight (ca. 10⁶ g/mol).
• Characterization of film properties (thickness, roughness, hydrophilicity) prepared at different pH values (4.5 and 7.2).
• Evaluation of antimicrobial efficacy against Escherichia coli and controlled release of Rose Bengal dye.

Main Results:

• Films prepared at pH 4.5 were thinner, smoother, and more hydrophilic than those at pH 7.2.
• Lower pH (4.5) led to extended chitosan conformation, promoting compact packing and reduced film thickness/roughness.
• Smoother films at pH 4.5 showed efficacy against Escherichia coli; rougher films at pH 7.2 facilitated controlled dye release.

Conclusions:

• Solution pH and chitosan DD¯ are key parameters for tuning HA/CHI LbL film properties.
• Tailored HA/CHI LbL films can be designed for specific applications, such as antimicrobial surfaces or controlled release systems.