Stability of polyelectrolytes complexes nanoparticles based on chitosan - Poly-2-acrylamido-2-methylprophane sulfonic acid in dilute sodium chloride solution

Polyelectrolyte complexes (PECs) is one of attractive materials for biomedical application because it can be prepared by simple mixing of oppositely charge polymers in aqueous solution. Electrostatic interaction between positively and negatively charged polymers play an important role on PEC stability. However, electrostatic interaction is not permanent crosslink and depend on their environment condition, such as salinity. In this research, PECs was prepared by simple mixing method between chitosan (positively charge polymers) solution and poly-2-acrylamido-2-methylprophane sulfonic acid (PAMPS; negatively charge polymers) solution. Stability of PECs in dilute sodium chloride solution was studied by comparing bare PECs sample with cross linked PECs sample after incubated for 2 weeks at room temperature. Visual observation suggested that particles size of bare PECs after 2 weeks is bigger than crosslinked-PECs. Further characterization using dynamic light scattering (DLS) method showed that particles size of bare PECs (759.9 nm) is bigger than crosslinked-PECs (166.0 nm). Morphological observation using scanning electron microscopy (SEM) method revealed that bare PECs particles were fused and formed bigger particles after 2 weeks, while particles size of crosslinked-PECs were stable enough after 2 weeks.