CTAB-modified chitosan nanocoatings: Increasing the cationic surface character by self-assembly

Area of Science:

• Materials Science
• Nanotechnology
• Biomaterials

Background:

• Chitosan is a biocompatible polymer with inherent antimicrobial properties.
• Surface modification of chitosan is crucial for enhancing its functionality.
• Cetyltrimethylammonium bromide (CTAB) is a cationic surfactant with antimicrobial activity.

Purpose of the Study:

• To develop and characterize CTAB-containing chitosan nanolayers on glass substrates.
• To investigate the effect of CTAB concentration on nanolayer structure and surface properties.
• To evaluate the antimicrobial efficacy of the developed nanocoatings.

Main Methods:

• Dip-coating technique for nanolayer deposition.
• UV-visible spectroscopy for thickness measurement.
• AFM, X-ray diffraction, and solid-state NMR for structural analysis.
• X-ray photoelectron spectroscopy and contact angle measurements for surface characterization.
• Zeta potential, turbidimetric, and colorimetric assays for antibacterial evaluation.

Main Results:

• Homogeneous nanolayers formed at low CTAB concentrations (0.25-1.0 mM).
• Phase separation and CTAB crystallite formation occurred at higher CTAB concentrations (>1.0 mM).
• Significant CTAB accumulation at the coating-air interface, increasing surface hydrophilicity.
• Increased positive surface charge (zeta potential) and over 80% inhibition of B. subtilis.

Conclusions:

• CTAB-chitosan nanolayers exhibit unique molecular structures with outward-oriented cationic head groups.
• The surface accumulation of CTAB enhances antimicrobial properties.
• These findings offer a robust strategy for developing advanced antimicrobial coatings.