Graphene Oxide-Based Nanocomposite For Targeting Colorectal Cancer Therapy

Colorectal cancer is a tumor of the digestive tract that humans often suffer.In recent years,the incidence of colorectal cancer has increased rapidly due to changes in people's diet.Chemotherapy is the main treatment method.Currently,the best chemotherapeutic drug for colorectal cancer is 5-fluorouracil,but the use of this effective treatment cannot improve the long-term survival of patients.In recent years,targeted therapy has attracted the attention of scientists.Clinically,high expression of EGFR mainly occurs in head and neck cancer and colorectal cancer,and the number of patients with colorectal cancer account for 79%.And two monoclonal antibodies for EGFR therapy are used clinically to treat colorectal cancer.Therefore,it is of clinical significance to use EGFR as a therapeutic target for colorectal cancer.In this project,we have constructed a method of loading 5-FU with graphene oxide nanomaterials,targeting EGFR,and combining with chemotherapy-photothermal therapy for colorectal cancer.Through in vivo and in vitro experiments,and analysis of the therapeutic effect,this method provides new ideas for clinical diagnosis and treatment strategies,and has potential reference value.(1)Preparation of 5-FU/GO-PEG-GE11:Graphene oxide(GO)nanosheet materials were prepared using the optimized Hummers method.The AFM and DLS were used to measure the average thickness and the average hydrated particle size of the GO nanosheet material was1.23 nm and 150 nm respectively.In order to make GO have good stability,polyglycol modification was used.The prepared GO-PEG nanosheet material was used as a carrier,and5-FU was loaded by electrostatic adsorption.Finally,the tumor cell epidermal growth factor targeting peptide GE11 was modified on its surface by amido reaction,and the5-FU/GO-PEG-GE11 nanocomposite was obtained.The near-infrared light(808 nm)laser was used to irradiate the nanomaterial,and record the temperature changes.The results confirm that GO has good photothermal properties.Using Ellman?s method to detect,GO has the ability to oxidize glutathione.(2)In vitro cell experimental verification:We selected HCT-116(EGFR~+)and SW-620(EGFR~-)cells as the experimental model.The biosafety of GO was confirmed by hemolytic toxicity and MTT experiments.Quantitative analysis was performed by using flow cytometry.Qualitative analysis was performed by using laser confocal microscopy.Localization analysis of nanomaterials entering cells was performed by using Z-stack technology.The results confirm that the nanocomposites enter tumor cells through the cell membrane,and have EGFR targeting ability.Finally,from MTT experiments with live cell/dead cell stained,it was confirmed that 5-FU/GO-PEG-GE11+NIR 808 nm experimental group has the best treatment effect.(3)In vivo experiments in mice:We constructed a subcutaneous tumor model of colorectal cancer nude mice with HCT-116 cells.RhB-labeled 5-FU/GO-PEG-GE11 and5-FU/GO-PEG nanomaterials were injected respectively.The fluorescence imaging system was used to observe and analyze the in vivo targeting ability of GO nanocomposites.The results showed that 5-FU/GO-PEG-GE11 material aggregated in the tumor site of mice and had the ability to target tumors.At the same time,the mice were randomly divided into eight groups and treated in different ways.The results showed that 5-FU/GO-PEG-GE11+NIR808 nm method had the best effect,and the tumor inhibition rate was 90.13%.Finally,the main organs of the mice were subjected to H&E staining to observe the morphological changes of the tissues,which confirmed that the nanocomposites have low biological toxicity in mice.In summary,we have successfully constructed a graphene oxide nanocomposite carrier5-FU/GO-PEG-GE11 with good targeting,stability and good effect of photothermal therapy.It has been confirmed in vivo/in vitro external experiments that the tumor nano-drug carrier has a good targeting ability and chemotherapy effect.It can be seen that the GO nanocomposite has potential practical value as a chemotherapy-photothermal therapy for colorectal cancer.