| In the 21 st century,cancer is expected to become the leading cause of death and a major obstacle to life expectancy in countries around the world.The prevention and treatment of cancer are very urgent and difficult.Chemotherapy is one of the main anti-tumor treatments,but due to its lack of specific recognition of tumor tissue,it has the disadvantages of side effects and low efficacy.With the development of nanotechnology,nanomaterials are gradually used for targeted drug delivery,especially for anti-tumor therapy,which has attracted more and more attention.Nanoparticles have many advantages for targeted drug delivery,for example,they are small in size and can escape the uptake of blood and mononuclear phagocytic system?MPS?.Furthermore,nanomaterials also have the function of targeting tumors and drug controlled release,thereby improving efficacy and reducing toxic side effects.Nanodiamonds?NDs?are gaining more and more attention due to their chemical inertness,optical stability and biocompatibility.In addition,the ferromagnetic Fe3O4 has also attracted the attention of researchers due to its good biocompatibility,abundant surface functional groups and strong magnetic properties.In this paper,a nanodiamond drug system?ND/Fe3O4/DOX,NFD?with magnetic targeting was successfully prepared.In the presence of an external magnetic field?MF?,human hepatoma?HepG2?cells were used as an in vitro model to study the biological effects of NFD on HepG2 cells.We hope it can provide theoretical basis for the development and application of drug delivery.The main research contents are as follows:1.Under aerobic conditions,the optimal ratio of n(Fe3+):n(Fe2+)required for the preparation of Fe3O4 with higher purity by chemical coprecipitation was investigated.Then polyethyleneimine?PEI?was used as surface modifier to prepare PEI-coated Fe3O4,which was combined with NDs oxidized by strong acid to obtain ND/Fe3O4?NF?magnetic nanocarriers.Finally,the anti-cancer drug Doxorubicin?DOX?was loaded in sodium citrate?Na3Cit?medium,and the ND/Fe3O4/DOX?NFD?magnetic nano drug system was successfully prepared.The structure was characterized by scanning electron microscopy?SEM?,Fourier transform infrared spectroscopy?FT-IR?and X-ray diffraction?XRD?.The loading of DOX on NFD was 354±5.23?g mg-1detected by UV-vis spectrophotometer.2.In the presence of MF and HepG2 cells as an in vitro model,the biological effects of NFD drug system on HepG2 cells were studied by flow cytometry,microscopic observation and laser scanning confocal microscope.From the results of flow cytometry,we found that NF magnetic materials have good biocompatibility.The uptake of NFD into HepG2 cells is clathrinand caveolin-mediated endocytic pathway,and the uptake is faster in the presence of MF,indicating that NFD has magnetic targeting.Confocal laser scanning showed that NFD were abundantly present in the cytoplasm and localized in lysosomes.It was proved by apoptosis experiments that NFD can cause a large number of cells apoptosis,and the effect is more obvious when the MF is present.In addition,it is confirmed by cell scratching that NFD effectively inhibits cell proliferation,and the effect is more obvious in the presence of a MF.3.GLY-DOX and ND-PGE-COOH were coupled by chemical bond?ester bond?to obtain a novel nanodiamond drug system?ND-PEG-GLY-DOX,NPGD?.From the simulated in vitro release of NPGD,it was found to be stable in physiological environment?pH 7.4?,suggesting that its toxic side effects are low.The cumulative release rate of NPGD in the lysosomal environment?p H 4.5?was about 50%,indicating that this is a p H-responsive drug release.The Q Exactive LC-MS/MS was used to characterize the successful preparation of GLY-DOX and NPGD.At the same time,an amide-linked ND-PEG-DOX?NPD?nanodiamond drug system was synthesized and simulated in vitro release,founding that the release rate was only about 20%,which proved that GLY-DOX and ND-PEG-COOH were coupled by ester bond. |
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