Fig 1.
Schematic view on liposome “Gluing”.
Synergistic effect of amphiphile and polyelectrolyte on their complexation with anionic liposomes and on the promoted structural stability of the resulting complexes upon salt addition.
Fig 2.
Chemical structures of lipids used.
I. POPS, II. DOPC, III. NBD PE.
Fig 3.
Chemical structures of polymers used.
A. (PPO45-b-PEO12)4, B. (qPDMAEMA100)3.1 with glucose core (red: PPO polymer segments interacting with interior liposome membrane; grey: hydrophilic “non-interacting” PEO segments; green: polymer segments interacting with the exterior liposome membrane (charged lipids).
Fig 4.
Course of size with varying “Glue” concentration.
The hydrodynamic radii for the liposome/(PEO12-b-PPO45)4 polymer complexes and the liposome/(qPDMAEMA100)3.1/(PEO12-b-PPO45)4 polymer complexes at different (PEO12-b-PPO45) concentrations. The lipids concentration is 6.37 x 10−5 mol/L. For one data set, the concentration of the positive charges of (qPDMAEMA100)3.1 was held constant at 1.9 x 10−6 mol/L. Tris Buffer pH = 7, 20°C (lines are a guide to the eye).
Fig 5.
Simplified scheme of the interaction between the PEO-PPO star-shaped polymer and two liposomes. The PPO block is represented in red and the PEO block in grey.
Fig 6.
2fFCS cross-correlation curves of lipids labelled with nitrobenzoxadiazole (NBD).[47] Liposomes (red curves) and complexes liposome/(PEO12-b-PPO45)4 (black curve) without NaCl. For a direct comparison, also the curve of the liposome scaled to the curve of the complex liposome/(PEO12-b-PPO45)4 is presented as red dotted line. The lipid concentration for each sample was 6.37 x 10−5 mol/L. The concentration of (PEO12-b-PPO45)4 was 7.5 × 10−7 mol/L. 10−2 mol/L Tris buffer was used at pH = 7, 20 °C.
Fig 7.
Schematic evolution during gluing with illustration of liposome/glue aggregate.
Size of the complex liposomes/(PEO12-b-PPO45)4 with the increase of concentration of (PEO12-b-PPO45)4 star shaped polymer, including a cryo-TEM image of liposome/(PEO12-b-PPO45)4 complexes (scale bar 100 nm; the liposome concentration is 0.05 mg/mL; the concentration of (PEO12-b-PPO45)4 is 7.5 × 10−7 mol/L; temperature 20 °C, 10−2 mol/L Tris Buffer, pH = 7).
Fig 8.
Conductivity of solutions with liposome/polymer complexes vs. time, the liposomes are loaded with 4 mol/L NaCl and 10−2 mol/L Tris buffer. The lipid concentration is 1.1 10−3 mol/L for each sample. The concentration of PEO12-b-PPO45 arms for the respective samples is 1.8 10−4 mol/L. If present, the concentration of the positive charges of (qPDMAEMA100)3.1 is 3.31 10−4 mol/L, it corresponds to Z = 0.3. Tris Buffer pH = 7, 20°C.
Fig 9.
Hydrodynamic radii of the (PEO12-b-PPO45)4, the liposome/(PEO12-b-PPO45)4 complexes, the liposome/(qPDMAEMA100)3.1/(PEO12-b-PPO45)4 complexes and the liposome/(qPDMAEMA100)3.1complexes at different NaCl concentrations. The lipid concentration for each sample is 6.37 x 10−5 mol/L. Where relevant, the concentration of the positive charges of (qPDMAEMA100)3.1 was held constant at 1.9 10−6 mol/L (which correspond to a charge ratio Z = 0.3, the liposomes are in excess). The concentration of (PEO12-b-PPO45) is 7.5 10−7 mol/L. Tris Buffer pH = 7, 20°C.