Stable polymersomes based on ionic–zwitterionic block copolymers modified with superparamagnetic iron oxide nanoparticles for biomedical applications
2015
Kania, Gabriela | Kwolek, Urszula | Nakai, Keita | Yusa, Shin-ichi | Bednar, Jan | Wójcik, Tomasz | Chłopicki, Stefan | Skórka, Tomasz | Szuwarzyński, Michał | Szczubiałka, Krzysztof | Kepczynski, Mariusz | Nowakowska, Maria
Stable polymersomes with semipermeable membranes were prepared by simple mixing of two oppositely charged diblock copolymers containing zwitterionic and cationic (PMPC₂₀-b-PMAPTAC₁₉₀) or anionic (PMPC₂₀-b-PAMPS₁₉₆) blocks. The formation of vesicular structures in the mixed solution of the block copolymers was confirmed by direct observation using the cryo-TEM technique. Superparamagnetic iron oxide nanoparticles coated with a cationic chitosan derivative (SPION/CCh) and decorated with a fluorescent probe molecule were next incorporated into the polymersome structure. The average diameter of SPION/CCh-polymersomes estimated using cryo-TEM was about 250 nm. Surface topography of the SPION/CCh-loaded vesicles was imaged using AFM and the magnetic properties of these objects were confirmed by MFM and MRI measurements. The ability of SPION/CCh-polymersomes to affect T₂ relaxation time in MRI was evaluated based on the measurements of r₂ relaxivity. The obtained value of r₂ (573 ± 10 mM⁻¹ s⁻¹) was quite high. The cytotoxicity and intracellular uptake of the SPION/CCh-loaded vesicles into EA.hy926 cells were studied. The results indicate that the SPION/CCh-polymersomes seem to be internalized by vascular endothelium and are not cytotoxic to endothelial cells up to 1 μg Fe per mL. Therefore, it can be suggested that SPION/CCh-polymersomes could prove useful as T₂ contrast agents in the MRI of endothelium.
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