Preparation and characterization of phosphatidyl-agar oligosaccharide liposomes for astaxanthin encapsulation

Surface modification of liposomes is an effective way to maintain the physicochemical activity of encapsulated substances. A novel astaxanthin (Ast)-based vesicle carrier system, namely, phosphatidyl-agar oligosaccharide (Ptd-AOS) liposomes (Lip), was prepared to improve the structural stability and in vitro digestibility of astaxanthin. During the transphosphatidylation reaction of synthesizing Ptd-AOS from phosphatidylcholine (PC) and AOS with different degrees of polymerization, phosphatidyl galactose (Ptd-Gal) and phosphatidyl neoagarobiose (Ptd-NA2) showed higher yields (85 and 96%, respectively). In terms of morphology, modified liposomes exhibited smaller particle sizes and more uniform dispersion compared with PC-Ast-Lip. In addition, the astaxanthin in the modified liposomes showed enhanced stability during liposome characterization and in vitro digestion. The transformations of astaxanthin in the modified liposomes were distributed in the range of 57-74% compared with free astaxanthin (25%). These findings suggest that the modification of liposomes by Ptd-AOS has potential applications in the delivery of functional ingredients.