Chitosan Nanoparticles: Preparation and Application in Antibacterial Paper

Chitosan nanoparticles (CSNP) were obtained by H2O2 degradation of chitosan. Their morphology and size were determined by atomic force microscope (AFM), and the particles were found smooth and approximately 36 nm in size. CSNP-0.5% HAc solutions (1, 2, 5, and 10 mg/mL) were used in antibacterial paper by addition in pulp, impregnation, dispersion coating on the handsheets, and insufflation. The antibacterial activity of CSNP against Escherichia coli and Staphylococcus aureus was measured by the inhibition zone and bacterial reduction methods. Results showed that the antibacterial activity of CSNP was improved with the increase in concentration. For E. coli, at a CSNP concentration of 5 mg/mL, the antibacterial rate reached approximately 95%. However, for S. aureus, the antibacterial rate only reached 81%. In addition, the antibacterial activity of the antibacterial paper was determined by inhibition zone method. The paper prepared by insufflation had the greatest activity. For E. coli, at a CSNP concentration of 10 mg/mL, the inhibition zone reached 8.0 mm. For S. aureus, the inhibition zone was 6.8 mm.