The Study Of A Multi-functional Drug Delivery System With Precise Tumor Mitochondria Targeting

The poor efficient tumor targeting performance and the severe toxicity of chemotherapy drug result in the unideal therapeutic effect,this subject select efficient photosensitive activity of Fullerene C60 as matrix,choose the triphenylphosphine(TPP)which has high affinity to mitochondrial membrane to modify it.Anticancer drug Rhein(RH)has been loaded on the surface of C60-TPP by physical adsorption efficiently,outside that the lipid shell was packaged,we build a study of precise targeting the mitochondria of tumor cells of a multi-functional drug delivery system(C60-TPP/RH@LIPO).The advantages are as follows.Firstly,precisely targeting the mitochondria of tumor cells makes the system efficiently position in the mitochondria of tumor cells,which can avoid the early release of RH,so that the curative effect is improved.Secondly,the injury of mitochondria is high-efficiency and synergic.With the irradiation of 532 nm laser,C60 generate a large amount of ROS,which injury the mitochondrial membrane and enhance the permeability.After that,more drug delivery system get into the mitochondria,RH block glycolysis in the mitochondria.At the same time,a large number of cytochrome C is released into cytoplasm,result in cell apoptosis.In addition,the protection of lipid shell can improve the system permeate body barrier and it is easier to be devoured by tumor cells,which can avoid the immune system identifying the drug delivery system.The main items are as follows:1.Preparation and characterization of C60-TPP/RH@LIPO.We choose fullerene C60 as underlying carrier and derive it with amino group.(4-carboxybutyl)triphenylphosphonium bromide(TPP)which is mitochondrial-targeted has been added to C60-TPP by the reaction of amide bond.The high adsorptive capacity of C60 can successfully load RH,and the drug loading efficiency is 70.1%.Eventually it is wrapped with lipid shell by reverse evaporation method.We characterize C60-TPP/RH@LIPO by UV-Vis,Fluorescence Spectrophotometre,Fourier Transform Infrared Spectroscopy(FT-IR),Transmission Electron Microscopy(TEM),Dynamic Laser light Scattering(DLS).The drug release behavior in vitro was studied.The final preparation is uniform spherical and the particle diameter is about 130 nm.The water solubility and stability is good.The drug release result indicated that contrasted with the physical mixture of RH and C60-TPP,C60-TPP/RH can significantly retard drug-releasing from the surface of C60-TPP,which is profitable for RH to get in mitochondria.The cumulative emission of RH which is loaded on C60-TPP of C60-TPP/RH@LIPO in 48 h is 72.44%.2.In vitro anti-tumor activity of C60-TPP/RH@LIPO.In this part,the studies were carried out based on human breast cancer cells MCF-7.The drug delivery system showed high security and is barely noxious for MCF-7.We studied the cytotoxicity,the inhibitory rate,the cell uptake,the ROS experiment,the membrane potential of mitochondria,the assay of ATP and the release of cytochrome C.Results showed that the drug delivery system could get in mitochondria of tumor cells in 3h;after 24 h,the inhibitory rate of C60-TPP/RH@LIPO+532nm Laser for MCF-7 cells reached 95.3%.After the cell trained with C60-TPP@LIPO for 24 h,the survival rate of MCF-7 was 90%,which proved that the drug delivery system was high security and had barely toxicity for MCF-7.Contrasted with C60-NH2/RH@LIPO,C60-TPP/RH@LIPO is more prominent at the inhibition effect of MCF-7.A huge number of ROS were generated by C60 under the irradiation of 532 nm laser.The ROS injured cell and after 48 h the cell inhibition rate of C60-TPP/RH@LIPO was 98.3%.After the 532 nm laser irradiating C60,the ROS released and damaged mitochondrial membrane.The lower mitochondrial membrane potential enhanced the permeability of the mitochondrial membrane which allowed more C60-TPP/RH arrive at mitochondrial.RH blocked glycolysis in mitochondrial was more efficient.Therefore,the generation of ATP was greatly reduced.At the same time,plenty of cytochrome c released into cytoplasm which resulted in cell apoptosis.3.In vivo anti-tumor activity of C60-TPP/RH@LIPO.We developed the S180 tumor bearing mice model to detect the tissue distribution and the tumor inhibition of C60-TPP/RH@LIPO.The results of tissue distribution showed that contrasted with RH,the distribution in liver and kidney of C60-TPP/RH@LIPO was greatly reduced,it was mainly gathered at the tumor site and showed favorable tumor targeting.The results of pharmacodynamics indicated that contrasted with other groups,C60-TPP/RH@LIPO+532nm laser could significantly restrain the growth of tumor and have no obvious injury for the normal tissues and organs,which highly improved the therapeutic index of RH.In general,a security and efficient drug delivery system was successfully developed,which could precise targeting the mitochondria of tumor cells.It has definite potential in the treatment of breast cancer.