Conformational Changes in High-Density Lipoprotein Nanoparticles Induced by High Payloads of Paramagnetic Lipids

High-density lipoprotein (HDL) nanoparticles doped with gadolinium lipids can be used as magnetic resonance imaging diagnostic agents for atherosclerosis. In this study, HDL nanoparticles with different molar fractions of gadolinium lipids (0 < <i>x</i>_Gd‑lipids < 0.33) were prepared, and the MR relaxivity values (<i>r</i>1 and <i>r</i>2) for all compositions were measured. Both <i>r</i>1 and <i>r</i>2 parameters reached a maximal value at a molar fraction of approximately <i>x</i>_Gd‑lipids = 0.2. Higher payloads of gadolinium did not significantly increase relaxivity values but induced changes in the structure of HDL, increasing the size of the particles from <i>d</i>_H = 8.2 ± 1.6 to 51.7 ± 7.3 nm. High payloads of gadolinium lipids trigger conformational changes in HDL, with potential effects on the in vivo behavior of the nanoparticles

Magnetite Nanoparticles for Stem Cell Labeling with High Efficiency and Long-Term in Vivo Tracking

Superparamagnetic iron oxide nanoparticles (<b>SPIO-PAA</b>), ultrasmall iron oxide nanoparticles (<b>USPIO-PAA</b>), and glucosamine-modified iron oxide nanoparticles (<b>USPIO-PAA-GlcN</b>) were studied as mesenchymal stem cell (MSCs) labels for cell tracking applications by magnetic resonance imaging (MRI). Pronounced differences were found in the labeling performance of the three samples in terms of cellular dose and labeling efficiency. In combination with polylysine, <b>SPIO-PAA</b> showed nonhomogeneous cell internalization, while for <b>USPIO-PAA</b> no uptake was found. On the contrary, <b>USPIO-PAA-GlcN</b> featured high cellular uptake and biocompatibility, and sensitive detection in both in vitro and in vivo experiments was found by MRI, showing that glucosamine functionalization can be an efficient strategy to increase cell uptake of ultrasmall iron oxide nanoparticles by MSCs