Chitosan-Coated Nanoliposomes: Exploring the Impact on Physicochemical Properties, Stability, Antioxidant Activity, and Molecular Characterization of Chlorella-Peptide Fractions

Abstract

The aim of this study was to characterize and evaluate the antioxidant activity of Chlorella peptide fractions coated with chitosan-modified nanoliposomes. Additionally, the release process of these peptide fractions under simulated gastric and intestinal conditions was evaluated. Protein hydrolysates were obtained from Chlorella through enzymatic hydrolysis, resulting in increased concentrations of antioxidant and hydrophobic amino acids. Peptide fractions were selected and separated based on their molecular weights, and it was observed that the fractions with lower molecular weights (less than 10 kDa, PF-10) contained higher amounts of hydrophobic and antioxidant amino acids. Among the fractions, PF-10 exhibited the highest radical inhibition activity for DPPH and ABTS, as well as enhanced reducing power and chelating activity towards copper ions. PF-10 and PF-30 (peptide fractions with a molecular weight less than 30 kDa) also demonstrated higher inhibition of nitric oxide radicals and total antioxidant activity (TAA) compared to the hydrolyzed form and other fractions. The analysis of physicochemical properties identified PF-10 as the most favorable treatment due to its size, polydispersity index (PDI), zeta potential, and encapsulation efficiency (EE). Coating the nanoliposomes with chitosan resulted in an increase in particle size and PDI but significantly improved the preservation of EE during storage. Chitosan coating also enhanced the activity of DPPH and OH radical scavenging. Fourier-transform infrared spectroscopy (FTIR) confirmed the localization of peptides within the polar regions and the bilayer membrane of nanoliposomes, while scanning electron microscopy (SEM) revealed agglomerated and spherical structures. Overall, our findings highlight the effectiveness of nanoliposomes as carriers for delivering peptide fractions with high antioxidant activity. The formulation of chitosan-coated nanoliposomes as carriers for Chlorella-peptide fractions represents an innovative advancement, providing opportunities for the creation of functional and stable formulations. These formulations hold the potential to provide benefits regarding human health and environmental considerations.