Protein-induced metamorphosis of unilamellar lipid vesicles to multilamellar hybrid vesicles

Conjugation‐Free Multilamellar Protein‐Lipid Hybrid Vesicles for Multifaceted Immune Responses

“…The main Bragg peaks of O-MPLVs were narrower than those of EGF-DOTAP MPLVs, which indicates that O-MPLVs had a denser multilamellar structure due to OVA with even charge distribution compared to EGF (Figure S2, Supporting Information). [14,16] Besides, in contrast to DNA-lipid complexes, no correlation peak was observed in our experiments because OVA did not form selfaggregates and fibrous structures. [17] To examine the protein antigen-lipid hybrid structures, we investigated protein antigen-induced morphological changes of LUVs using cryo-TEM (Figure 1C).…”

“…The decreased size of O-MPLVs indicates that LUVs undergo dramatic morphological changes by OVA-mediated vesicular assembly, as recently demonstrated for epidermal growth factor (EGF). [14] Besides, the zeta potential of O-MPLVs (27.5 ± 0.6 mV) was lower than that of DOTAP LUVs (46.0 ± 0.7 mV) because the binding of negatively charged OVA reduced the surface charges of DOTAP LUVs, though no charge conversion was observed. The results indicate that the cationic LUVs do not simply attract the added OVA but experienced dramatic structural change while OVA is incorporated into the aqueous layers of multilamellar structures with a limited number of OVA exposed to the vesicle surface.…”

“…Preparation of Unilamellar Lipid Vesicles: To form a lipid thin film, 20 mg mL -1 DOTAP was dried in chloroform in a 10 mL glass vial with a gentle stream of nitrogen gas, followed by vacuum drying for 16 h. [14] The hydration of dried lipid thin film was performed with deionized water at 37 ˚C for 2 h. The hydrated lipid nanovesicles were transformed into LUVs using a mini extruder kit (Avanti Polar Lipid Inc., Alabaster, AL, USA) according to the manufacturer's instruction. The size distribution and zeta potential of vesicles were determined by DLS (ELSZ-1000, Otsuka Electronics, Osaka, Japan).…”

“…The results indicate that the cationic LUVs do not simply attract the added OVA but experienced dramatic structural change while OVA is incorporated into the aqueous layers of multilamellar structures with a limited number of OVA exposed to the vesicle surface. [14] Note that O-MPLVs had a high protein antigen loading efficiency of 93.6 ± 0.1% (the loading yield ≈ 18.7%) at WR = 0.25. The increased hydrodynamic diameter of O-MPLVs at WR = 0.5 was attributed to the OVA-induced aggregation of vesicles because the transmission of O-MPLVs decreased with the increased WR while the number of lipid layers was not significantly changed (Figure S1A, Supporting Information).…”

“…The morphological changes were ascribed to the OVA-induced rearrangement of lipid molecules on the surface of LUVs. [14] As MPLVs were assembled, the thickness of the DOTAP bilayer increased from 4.2 ± 0.4 to 6.8 ± 0.5 nm due to the binding of OVA. The difference (≈4.4 nm) between d lamellar (≈11.2 nm) and lipid membrane thickness (≈6.8 nm) was com-parable to the size of OVA (7.2 × 3.3 × 3.0 nm) with an ellipsoidal shape, indicating that OVA with even charge distribution might bind to the lipid bilayers in the long axis direction.…”