Qi, Xu, Jiang, Hu,
and Zou (2004) reported that chitosan nanoparticles exhibit higher
antibacterial activity against Escherichia coli, Staphylococcus aureus
and Salmonella typhimurium than chitosan on account of the special
character of the nanoparticles, likely the nanoparticle's larger surface
area and higher affinity with bacteria cells, which yields a
quantum-size effect. Conversely, Sadeghi et al. (2008) reported that
chitosan nanoparticles have less inhibition effect on S. aureus than
the polymers in free soluble form since nanoparticles have less
positive charge available to bind to the negative bacterial cell wall.
Du et al. (2009), reported that chitosan tripolyphosphate nanoparticles
loaded with various metal ions exhibit higher antibacterial
activity against E. coli, Salmonella choleraesuis and S. aureus.