摘要

In order to enhance the stability of liposomes, the surface of Vitamin C (Vc)/β-carotene (βC) composite liposomes (L) were modified by chitosan and sodium alginate with layer-by-layer technique, to prepare monolayered chitosan liposomes (C-L) and bilayered sodium alginate-chitosan liposomes (S-C-L). The encapsulation efficiency, particle size distribution, microscopic morphology, formation mechanism and storage stability of the liposomes were studied. The results showed that there was no significant change in the encapsulation efficiency of the active components in the liposomes before and after a liposomal surface modification, with the encapsulation efficiency of Vc and βC higher than 75% and 95%, respectively. The results obtained dynamic light scattering (DLS) and transmission electron microscopy (TEM) showed that after surface modification, the z-average particle size of liposomes increased from 250.1 nm to 541.9 nm. The Zeta-potential measurements and FT-IR analysis showed that chitosan and sodium alginate could successfully modify the surface of liposomes via electrostatic interactions, without changing the internal structure of the liposomes. The results of storage stability tests showed that the retention rates of Vc and βC in C-L and S-C-L were about 2%~10% higher than that of L under the same conditions, indicating that the storage stability of liposomes was enhanced after surface modification.