Steam-sterilizable cationic nanodiamond-silver composites with enhanced antibacterial activity

Area of Science:

• Materials Science
• Nanotechnology
• Biomedical Engineering

Background:

• Hydrogenated nanodiamonds (H-NDs) offer biocompatibility but have limited antibacterial activity.
• Existing silver-nanodiamond (ND-Ag) composites often rely on protein stabilization, limiting sterilization options.

Purpose of the Study:

• To engineer stable, antibacterial silver-nanodiamond composites (H-ND-Ag) compatible with steam sterilization.
• To investigate the influence of H-ND-Ag properties on antibacterial efficacy and colloidal stability.

Main Methods:

• H-NDs were coated with chitosan and functionalized with silver nanoparticles (AgNPs) using polyethyleneimine.
• The effects of autoclaving on H-ND and H-ND-Ag surface chemistry and dispersion were analyzed.
• Antibacterial activity against Escherichia coli and Staphylococcus aureus was evaluated.

Main Results:

• Autoclaving destabilized pristine H-NDs, reducing their ζ-potential and causing aggregation.
• The chitosan-Ag shell maintained the positive surface charge and colloidal stability of H-ND-Ag after autoclaving.
• H-ND-Ag composites demonstrated significant antibacterial activity at low concentrations, outperforming protein-stabilized benchmarks.

Conclusions:

• A protein-free, autoclave-sterilization-compatible method for creating durable antibacterial nanodiamonds was established.
• Antibacterial efficacy is primarily governed by carrier size and silver distribution, not solely surface charge.
• H-ND-Ag composites represent a promising platform for developing advanced antibacterial materials.