CA was coupled to CS by the formation of amide linkages through
an EDC-mediated reaction following the method proposed by . First, CS (0.5 g) was dissolved in 100 mL of aqueous acetic acid (1% v/v). Then, 85 mL of methanol was added and the resulting solution was sonicated. On the other hand, EDC (668 uL)
was mixed with 221 mg of CA. Then, both solutions were mixed
and stirred for 5 h. After that, pH was adjusted at 8.5–9 using
sodium hydroxide (1 M) to precipitate the nanogel. The mixture
was then centrifuged to recover the precipitated nanogel. The
obtained nanogel was then washed with ethanol and distilled water
to remove un-reacted materials followed by drying under vacuum
for 24 h at room temperature. The clear nanogel solution was then
filtered through a 0.2 m filter (Whatman).