Surface-quaternized chitosan particles as an alternative and effective organic antibacterial material

Area of Science:

• Materials Science
• Biotechnology
• Organic Chemistry

Background:

• Chitosan, a natural polymer, possesses inherent antibacterial properties but requires modification for enhanced efficacy and broader applications.
• Quaternary ammonium compounds are known for their potent antimicrobial activity.
• Developing sustainable and biocompatible antibacterial agents is crucial for various industries.

Purpose of the Study:

• To develop novel, environmentally friendly, organic antibacterial material from quaternized chitosan particles.
• To investigate the antibacterial efficacy of these particles against Gram-positive and Gram-negative bacteria.
• To explore potential applications in biomedical devices, health, and textile industries.

Main Methods:

• Chitosan was ionically crosslinked with tripolyphosphate and subsequently quaternized.
• Quaternization was achieved through direct methylation or reductive N-alkylation followed by methylation.
• Particle characterization included (1)H NMR, FT-IR, dynamic light scattering (PCS), and transmission electron microscopy (TEM).
• Antibacterial activity was assessed using viable cell counts and minimum inhibitory concentration (MIC) assays.
• Bacterial morphology changes were observed using microscopy.

Main Results:

• Sub-micron, spherical, positively charged quaternized chitosan particles were successfully synthesized.
• All quaternized chitosan particles demonstrated superior antibacterial activity against Staphylococcus aureus compared to native chitosan at neutral pH.
• Efficacy against Escherichia coli varied, with particles possessing high charge density and large alkyl groups showing significant suppression.
• Minimum inhibitory concentrations (MIC) were determined, quantifying the inhibitory efficiency.
• Microscopic analysis revealed morphological damage to bacterial cells upon exposure to quaternized chitosan particles.

Conclusions:

• Quaternized chitosan particles represent a promising class of organic, environmentally friendly antibacterial materials.
• These particles exhibit significant potential for use in biomedical devices, healthcare products, and the textile industry due to their potent antibacterial properties.
• The quaternization strategy allows for tunable antibacterial efficacy, particularly against Gram-positive bacteria, with potential for Gram-negative bacteria targeting.