2. Materials and methods
2.1. Chitosan and oligochitosan
Chitosan with 90% deacetylation and viscosity average molecular
weight of 350 kDa dissolved at 25 g/L in 1% HCl by stirring at
room temperature, and the original solution was then diluted to
a series of 0.1, 0.3, 0.5, 0.7, 1.0, 2.0 and 5.0 g/L, and the pH value
of each solution was adjusted to 5.5 with NaOH. Oligochitosan
with average molecular weight 6 kDa was dissolved in sterile distilled
water at 25 g/L, and the original solution was then diluted to
a series of the concentrations as the same as chitosan at pH 5.5.