RESUMO
Size and surface modification are the two key factors affecting the effect of macrophages polarization induced by superparamagnetic iron oxide nanoparticles (SPIONs). The smaller the particle size, the better the polarization effect of SPIONs. Besides, the reasonable SPIONs surface modification method can also be used to enhance the polarization effect. In this study, SPIONs was prepared by solvothermal method and optimized by Box-Benhnken center combination design and response surface method. Furthermore, astragalus polysaccharide-superparamagnetic iron oxide nanocomplex (APS-SPIONs) was successfully constructed by EDC/NHS esterification method. The structure of APS-SPIONs was confirmed by dynamic light scatter and infrared spectrometer, and the contents of iron and polysaccharide were characterized by spectrophotometry. The effect of APS-SPIONs on inducing mouse macrophages RAW264.7 polarization was investigated by flow cytometry. The RAW264.7 macrophages-HepG2 human hepatoma cancer cells Transwell co-culture system was established to investigate APS-SPIONs improve anti-tumor function of macrophages in vitro, and the proliferation activity of APS-SPIONs on RAW264.7 detected by cell counting kit-8 (CCK-8) method. The results showed that the average particle size and zeta potential of APS-SPIONs were (82.93 ± 1.47) nm and (-24.00 ± 0.47) mV. Polysaccharide and Fe content were 8.69% and 7.04%, respectively. APS-SPIONs effectively induced the polarization of RAW264.7 into M1 type in vitro, improving the anti-tumor ability of macrophages in a co-culture system, without effecting the proliferation of macrophages. Our study provides a drug development strategy and preliminary research results to educate macrophages and reshape the tumor immune microenvironment to achieve tumor-killing effects.
RESUMO
In this study, water-dispersible magnetic iron oxide (Fe3O4) nanoparticles were synthesized with solvothermal method. The nanoparticles were characterized with a transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The in vitro magnetic resonance response and photothermal conversion characteristics of the nanoparticles were evaluated. In addition, the cellular uptake, cytotoxicity and biodistribution were studied. Finally, magnetic resonance/photothermal dual-modal imaging effect of the as-synthesized Fe3O4 nanoparticles was investigated in the tumor-bearing mice. The results showed that the obtained magnetic nanoparticles were uniform with a mean diameter of about 125 nm. Moreover, the superparamagnetic Fe3O4 nanoparticles showed remarkable magnetic resonance response and photothermal conversion properties. The results of cellular experiments showed that the cell viability was nearly 85% even the concentration of the nanoparticles was up to 1 000 μg·mL-1, an indicator of good biocompatibility. In addition, the nanoparticles could be taken up by the tumor cells and then located in the cytoplasm. After intravenous injection, the nanoparticles were tended to enrich in the tumor over time, which is helpful in achieving dual-modal magnetic resonance/photothermal imaging. In sum, the obtained Fe3O4 nanoparticles showed great potential to be applied for multi-modal bio-imaging which may play an important role in the diagnosis of tumors.