TEM Investigation Of Antitumor Effect On Gastric Cancer Cells Treated By Fe₃O₄-CMC-5FU

Objective:The present research was to conduct5-fluorouracil loaded nanodrugs which used polyhedral Fe3O4nanoparticle as core treated gastric cancer cells. Electron-microscopy techniques was used in vitro experiment in order to explore the antitumor mechanism of nano-dugs and provide theory basis for development and application of nanodrug.METHODS:Size-and shape-controlled Fe3O4nanoparticles were prepared by using a high temperature liquid phase method. Fe3O4nanoparticles was coated by CMC in order to improve biocompatibility, further immobilize5-Fu onto the CMC coated Fe3O4-CMC NPs. The Fe3O4-CMC-5FU nanomedicine was then collected from the reaction mixture by using a magnet. The chemical bonding of the conjugated Fe3O4-CMC and Fe3O4-CMC-5-FU nanomedicine were investigated by an infrared spectroscopy (IR). A cell counting kit-8(CCK-8) was used to determine the inhibition of drugs (Fe3O4NPs,5FU and Fe3O4-CMC-5FU) against SGC-7901cells. Annexin-V-FITC/PI double staining assay was performed to detect apoptosis of SGC-7901cells. The morphology, crystal structure and chemical characterization of individual Fe3O4, Fe3O4-CMC, Fe3O4-CMC-5-FU, SGC-7901cells incubated with5FU, Fe3O4NPs and Fe3O4-CMC-5-FU nanomedicine were analyzed at the nano/atomic-scale using field emission high-resolution transmission electron microscopywhich is equipped with energy-dispersive x-ray analysis (EDAX), high angle annular dark and scanning transmission electron microscope (HAADF-STEM). The results of ultra-structure changes were Composited to make a deduce which leaded us to draw a analogue map which displayed antitumor effectiveness by nanomedicines.Results:Fe3O4NPs with10nm diameter and polyhedral shape were therefore chosen in this study.Both HAADF-STEM and TEM images reveal that individual Fe3O4NPs are fairly uniform and monodispersed. The Fe3O4-CMC hybrids had a mean size of approximately12nm. The average diameter of the Fe3O4-CMC-5FU nanomedicine is about13nm, nearly an ideal diameter of nanomedicines. The data demonstrate that the Fe3O4-CMC-5FU nanomedicine has a much better effect in inhibiting SGC-7901proliferation at all tested concentrations than the traditional pure5FU. The data demonstrate that the Fe3O4-CMC-5FU nanomedicine has a much better effect in inhibiting SGC-7901proliferation at all tested concentrations than the traditional pure5FU. Apoptosis rate detected by flow cytometry reveals that the Fe3O4-CMC-5FU nanomedicine promotes the apoptosis and necrosis of SGC-7901cells much better than the traditional pure5FU. The intensity of apotosis also indicates that the apotosis-inducing effect of the Fe3O4-CMC-5FU nanomedicine on SGC-7901cells is also dose-and time-dependent. We examined218SGC-7901cells incubated with50μg-ml-1Fe3O4-CMC-5FU nanomedicine under transmission electron microscope and found that161cells promoted apotosis due to the mitochondrial death, taking up about74%of the apotosis cases. It is clearly evident that a large amount of5FU was still retained to conjugate with Fe Fe3O4-CMC after24h incubation and5FU should be slowly and continuously released from the surface of the Fe Fe3O4-CMC-5FU nanomedicine agglomerates, thus forming a localized high concentration of5FU in the cytoplasm of SGC-7901cancer cells may induce an acute injury of mitochondrial membrane structure including mitochondria death.Conclusions:Fe3O4-CMC-5FU nanomedicine apparently enhances antitumor effect on gastric cancer cells. The enhanced therapeutic efficacy derives from the localized high-concentration of the magnetic nanomedicine in the cytoplasm. Mitochondrial pathway is not only the main reason which enhanced antitumor activity of nanomedicine, but also the new evidence for nanomedicine treating tumour.