Purified and biocompatible magnetoliposomes highly loaded with superparamagnetic iron oxide nanoparticles (SPIONs)

Magnetoliposomes (MLs) have great potential in the biomedical field. However, their, purification, characterization, and biological evaluation are relatively poorly investigated. In this work, we present a thorough study about not only the elaboration and the characterization, but also the cytotoxicity evaluation of 130 nm MLs, densely loaded in superparamagnetic iron oxide nanoparticles (SPIONs). Magnetite (Fe 3 O 4 ) SPIONs surface-stabilized with citric acid (CA) were synthesized by coprecipitation, and MLs were obtained by hydrating a lipid film with an aqueous suspension of these surface-stabilized SPIONs. An efficient two-step purification process was also developed, involving a salt-induced-aggregation (SIA) followed by a magnetic chromatography (MC). DLS, zetametry, and cryo-TEM analyses were performed after each step, showing that SIA and MC enabled a drastic removal of unencapsulated SPIONs, as well as empty liposomes, respectively. The quantitative evolution of iron (a constituting element of SPIONs) and phosphorous (a constituting element of lipids) was monitored by ICP-MS before and along each purification step, highlighting the efficiency of this purification process. According to cryo-TEM images, final MLs were found to be pure, and densely loaded in SPIONs. Finally, SPIONs, liposomes, and MLs were put in contact with primary canine fibroblasts for cytotoxicity evaluation. After 72 h, SPIONs were found biocompatible (cell viability above 70%) up to a concentration of 250 µg/mL, and liposomes up to at least 0.68 mM. Concerning purified MLs with an iron concentration of 60 µg/mL, they were very well tolerated by the cells, showing a cell viability of 90.5 ± 3.0% after 72 h.