Macrophages as immunocyte are attracting more and more attention in cancer therapy. Our previous study observed that dimercaptosuccinic acid (DMSA)-coated Fe3O4 magnetic nanoparticles triggered comprehensive immune responses of mouse macrophages (RAW264.7 cells) and induced production of many kinds of cytokines. This study investigated the effects of Fe3O4 magnetic nanoparticles on RAW264.7 cells proliferation, migration, and inhibition of tumor growth in vitro. Fe3O4 magnetic nanoparticles had an average size of about 11 nm with good dispersibility and uniformity. Fe3O4 magnetic nanoparticles internalized efficiently into RAW264.7 cells. Through Cell Counting Kit-8 (CCK-8) detection, the proliferation of RAW264.7 cells significantly increased by the low-dose Fe3O4 magnetic nanoparticles (50 µg/mL) treatment. The results of wound-healing and Transwell assays both displayed a significant promotion of the RAW264.7 cells migratory capability compared with control group ( P<0.01). It is interesting to find that a large number of proliferated RAW264.7 cells were activated to surround quickly and attack mouse liver cancer cell (Hepa1-6) cells by Fe3O4 magnetic nanoparticles. The growth of Hepa1-6 cells was effectively inhibited according to microscope imaging and flow cytometry analysis. The inhibition may be cooperative effects of RAW264.7 cells proliferation, migration, and immune activation. The results suggest potential clinical value of low-dose iron oxide nanomaterials in cancer therapy.

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The iron oxide nanoparticles (FeNPs) are widely used in biomedicine for good biocompatibility. To promote its safe application, any potential nanotoxicity should be thoroughly and carefully investigated. This paper systematically summarizes our lab's research on the nanotoxicity of iron oxide nanoparticles coated with dimercaptosuccinic acid (DMSA), including the effects of FeNPs on viability, apoptosis, cycle, and oxidative stress at cell level. In vitro studies revealed that the FeNPs showed obvious apoptosis of human acute monocyte cells (THP-1) and human hepatoma cells (HepG2) at the highest concentration. FeNPs resulted in common and cell typespecific nanotoxicities of the FeNPs to both human and mouse cells at the gene, disturbed cell's iron and osmosis homeostasis by the internalization of FeNPs through releasing iron ion in cells, resulted in cytotoxicity of DMSA as coating molecules of FeNPs and the inhibitor of DNA binding/differentiation (Id) related nanotoxicity of FeNPs at gene level. The studies of our lab shed many new insights into the nanotoxicity of the nanoparticle. Furthermore, the toxicity may play more value if it is guided and applied reasonably, such as iron supplement, anti-oxidation, and immunotherapy.

Nowadays, self‐fluorescent materials such as quantum dots are widely studied and applied in biomedical field. However, the biggest obstacle is biocompatibility. Here, a novel autofluorescent nanoparticle is constructed by crosslinking polyacrylamide nanoparticles (PAANPs) that contain ε‐poly‐l‐lysine with glutaraldehyde (named fPAANPs). The nanoparticle has a mean size of about 16 nm, a zeta potential of about +16 mV, and strong visible and near‐infrared autofluorescence. The nanoparticle can be efficiently internalized into cells with high biocompatibility, the LC50 of which in RAW264.7, HepG2, and Hepa1‐6 cells is 6, 9, and 7.5 mg mL−1, respectively. The nanoparticle shows no visible impact on the mice vitality even at a high intravenously administered dose (126 mg kg−1). The autofluorescence of fPAANPs shows high stability, persistence, allowing long‐term dynamic imaging for 25 d in subcutaneous injections and 18 d in xenograft tumors in mice. The nanoparticle thus provides a self‐traceable nanomaterial that can be exploited as drug carrier and potential photodynamic therapy photosensitizer.