Production and Characterization of Nanoparticulate Polyelectrolyte Complexes of Chitosan–Catechol, Ulvan, and Hyaluronic Acid

This work provides the first description of the synthesis and characterization of polymeric nanoparticles (NPs) obtained by polyelectrolyte complexes (PECs) of three polysaccharides: chitosan (Cs) or its catecholic derivative, ulvan, and hyaluronic acid (HA). The carbodiimide method used catechol group conjugation onto the Cs backbone using the catechol-containing compound hydrocaffeic acid. A degree of substitution of 2.98% was determined by spectroscopy in the chitosan-catechol (CsC) conjugate. DLS studies showed hydrodynamic diameter (<i>D</i> _h) close to 300 nm for PECs of Cs and CsC with ulvan, with positive zeta potential for both complexes. HA coating was confirmed by obtaining negative zeta potential. The HA coating reduced the <i>D</i> _h values of the materials by approximately 100 nm. This resulted in maintaining stability in water suspension for up to 8 weeks, yielding unimodal size distribution. ATR-FTIR spectra confirmed the presence of the polyelectrolytes in the PECs. FE-SEM studies demonstrated that HA-coated NPs exhibited smaller sizes than their uncoated counterparts. PECs with CsC maintained higher free radical scavenging activity than those with unmodified Cs, with the HA coating only reducing antioxidant activity by 16%. All tested NPs demonstrated biocompatibility at concentrations up to 200 μg/mL in ARPE-19 cell cultures derived from human retinal pigment epithelial cells.