Chitosan nanoparticles were prepared based on the ionotropic
gelation between chitosan and sodium tripolyphosphate. Briefly,
chitosan with the deacetylation degree (DD) of 83% and molecular
weight (Mw) of 850 kDa was dissolved in 1% (v/v) acetic acid to
obtain a 2% (w/v) chitosan solution. Sodium tripolyphosphate was
dissolved inwater to a concentration of 2%. Under magnetic stirring
at room temperature, 4 ml of tripolyphosphate solution was added
into 100 ml of chitosan solution. The mixture was stirred for
60 min, then, treated with sonication at 1.5 kW for 10 min before
being used for further analysis (Du et al., 2009). Particle size and
zeta potential were measured using a Zetasizer Nano-ZS-90 (Malvern
Instruments). The analysiswas performed at a scattering angle
of 90 at 25 C. For zeta potential measurements, samples were
dispersed in water and measured under the automatic mode