Nano-liposomal delivery of Gracilaria corticata bioactive peptides for improved stability and controlled gastrointestinal release

This study aimed to develop and evaluate a liposomal nano-delivery system for bioactive peptide fractions (PFs) derived from Gracilaria corticata algae proteins. The peptides were obtained by enzymatic hydrolysis using alcalase, pancreatin, and trypsin. The resulting PF-loaded nanoliposomes were characterized in terms of degree of hydrolysis (DH), particle size, ζ-potential, encapsulation efficiency (EE), and antioxidant capacity (DPPH and ABTS assays). Among the tested enzymes, alcalase produced hydrolysates with the highest DH (33%) and EE (84%). The particle size of nanoliposomes ranged from 68.1 to 78.1 nm, with PDI values between 0.28 and 0.32, indicating good size uniformity. ζ-potential values became more negative upon PF encapsulation (from − 7.90 to − 15.80 mV), enhancing colloidal stability. Antioxidant activity of the PF-loaded liposomes was preserved, with maximum DPPH and ABTS radical scavenging observed for alcalase and pancreatin hydrolysates, respectively. Hydrolysates obtained with alcalase were chosen for further studies. Further structural and thermal analyses (TEM, FTIR, and DSC) confirmed successful PF encapsulation and improved thermal stability. TEM and FTIR analyses confirmed the spherical morphology and successful peptide encapsulation within the liposomal bilayer. In vitro release studies in simulated gastric and intestinal fluids demonstrated sustained release, with minimal PF release (7.45%) in gastric conditions and controlled release up to 95.4% under intestinal conditions. These findings suggest that nano-liposomal encapsulation is an effective strategy to enhance the stability, bioactivity, and delivery of marine-derived peptides in functional food or nutraceutical applications.