Polysaccharides as Nanomaterials for Therapeutics - Harnessing Biomaterials in Nanomedicine: Preparation, Toxicity, and Applications - page 131

linking reaction, most crucial are the size of the cross-linker and
the global charge of the cross-linker and the polysaccharide [48,
57]. Unlike covalently cross-linked nanoparticles, ionic cross-linked
nanoparticles are generally pH sensitive, a welcome trait for drug
delivery purposes. However, this pH sensitivity also contributes to
instability of the ionic cross-linked network [48, 58, 59].
Figure 5.2 Common mechanism for polysaccharide based nanoparticle
preparation. (A) Covalent cross-linking. (B) Ionic cross-linking. (C)
Polyelectrolyte complexation (PEC). (D) Self-assembly of hydrophobically
modified polysaccharides. See also Color Insert.