The CMC hybrid hydrogel containing NP-NH2 was prepared using a procedure already reported in the
literature [12,17]. Briefly, 1 g of CMC was first dissolved in deionized water at a concentration of
1.5% w/v. N-Hydroxysuccinimide (NHS) and N-(3-dimethylaminopropyl)-N-ethyl-carbodiimide
hydrochloride (EDC) were then added to this solution at a molar ratio of 0.5 relative to the moles of the
carboxyl groups of the polysaccharide.
0.5 g of NP-NH2 was added to the mixture and the pH was adjusted to 4.5 with 1 M HCl. Once
formed, the hydrogel was purified by washing in water until no traces of EDC or NHS were revealed
by UV and FT-IR spectroscopy. A hydrogel was also prepared using 1,3-diaminopropane (DAP) as
cross-linker according to a previously described procedure, and was referred to as the control sample
(CMC-DAP) [1].