Thanks a lot. I found an article by Beduneau et al 2009 (Facilitated Monocyte-Macrophage Uptake and Tissue
Distribution of Superparmagnetic Iron-Oxide
Nanoparticles) that mononuclear phagocytes prefer negative charged elements. Please, why do you recommend positive charged coating with PEI?? Do you have any experience?
Same as the answer from Wencheng Zhu, I would like to just add that the best material for the magnetic core regarding MRI applications would be magnetite Fe3O4. We did some work on dendritic cells extracted from peripheral blood mononuclear cells (PBMCs) primary monocites, using particles with Nh2+ and COO- negative charge (see attach's.). Maybe this can help.
Thank you very much, I would never check citations by professor from Johns Hopkins University - I suggested that was correct. Also thanks for articles those help us to choose right coating.