O-Carboxymethyl chitosan-based pH-responsive amphiphilic chitosan derivatives: Characterization, aggregation...

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Nanotechnology

Background:

• Chitosan is widely explored for drug delivery applications.
• Carboxymethyl chitosan (CMC)-based self-aggregated nanocarriers are rarely reported.
• Development of novel chitosan derivatives for advanced drug delivery systems is ongoing.

Purpose of the Study:

• Synthesize and characterize novel CMC-based amphiphilic chitosan derivatives (HBCC and H2ECC).
• Investigate the potential of these derivatives as pH-responsive nanocarriers for drug delivery.
• Evaluate the antibacterial activity and toxicity of the synthesized materials.

Main Methods:

• Homogeneous synthesis of N-2-hydroxylpropyl-3-butyl ether-O-carboxymethyl chitosan (HBCC) and N-2-hydroxylpropyl-3-(2-ethylhexyl glycidyl ether)-O-carboxymethyl chitosan (H2ECC).
• Characterization using FTIR, 1H NMR, 13C NMR, and XRD.
• Determination of critical aggregation concentrations (CACs) and aggregate particle size.
• Assessment of cytotoxicity and antibacterial activity against Staphylococcus aureus and Escherichia coli.

Main Results:

• Optimized synthesis conditions achieved (4 h, 80 °C, n_epoxy/n_NH2 = 3/1).
• XRD confirmed decreased crystallinity due to hydrophobic segment introduction.
• Improved thermostability and increased glass transition temperature (Tg) observed.
• Low CACs (HBCC: 0.66-1.56 g/L, H2ECC: 0.57-1.07 g/L) and moderate particle size.
• Curcumin-loaded aggregates showed no toxicity.
• Demonstrated significant antibacterial activity against S. aureus and E. coli.

Conclusions:

• HBCC and H2ECC are successfully synthesized CMC-based amphiphilic chitosan derivatives.
• These derivatives form stable, pH-responsive nanocarriers suitable for drug delivery.
• The materials exhibit excellent biocompatibility and potent antibacterial properties.
• HBCC and H2ECC show promise as dual-functional curcumin nanocarriers and antibacterial agents.