Folic Acid-decorated Reactive Oxygen Species-responsive Dextran-block-poly(Propylene Sulfide) Copolymer For Target Oncotherapy

BackgroundCancer is one of the leading causes of death globally and chemotherapy remains one of the most traditional methods of cancer treatment.However,traditional chemotherapy drugs have problems such as high toxicity,poor targeting,and significant systemic toxicity reactions,which limit the application in clinical practice.In recent years,rapidly developing cancer immunotherapy also has problems with multiple adverse reactions caused by drug delivery methods.Therefore,searching for effective drugs and delivery methods for cancer treatment is extremely important.Among them,nano-block copolymer micelles are very promising.With the continuous development of nanotechnology,the application of nano-block copolymer micelles in medicine has become more and more extensive.Nano-block copolymer micelles have good biocompatibility,strong stability,fine modifiability,and high drug loading capacity,making them excellent nanocarriers for anti-cancer drugs.Researchers have used the hydrophilicity and hydrophobicity of nano-block copolymer micelles to modify and load various anti-cancer drugs.By customizing their targeting,the micelles achieve the targeted drug release while reducing drug toxicity and adverse reactions,show their great potential to be carriers for anti-cancer drugs.In the research of block copolymer micelle carriers for anti-cancer drugs,micelles with reactive oxygen species(ROS)response are an important direction.Many studies have shown that the concentration of ROS is higher in the tumor microenvironment than in normal tissues.Therefore,using reducible block copolymer micelles to load drugs can achieve aggregation and release in the tumor microenvironment,which is a feasible method to increase and accumulate drug concentration.Many studies have also shown that the folate(FA)receptors are overexpressed in most tumor cells.By combining folate with anti-tumor drugs through antigen-antibody binding reactions,the feasibility of achieving targeted drug delivery has also been demonstrated by many studies.Hence,in this study we synthesized a folate-targeted,reducible triazole-linked amphiphilic folate-modified active oxygen-responsive dextran(polypropylene sulfide)block copolymer loaded with doxorubicin(FA-Dex-b-PPS-Dox),and further studied its feasibility as a nanodrug for cancer targeted therapy and anti-cancer effect.Methods1.The chemical structure of FA-Dex-b-PPS and various intermediates were verified using Fourier transform infrared spectroscopy(FITR)and ~1H nuclear magnetic resonance(~1H NMR).2.The behavior of FA-Dex-b-PPS self-assembling into ROS-responsive micelles and its degradation conditions were characterized by fluorescence spectroscopy,dynamic light scattering(DLS),and transmission electron microscopy(TEM).The critical micelle concentration(CMC)of the copolymer nanoparticles was determined using a fluorescence probe method.The therapeutic copolymer nanocarrier loaded with Dox was prepared using dialysis.3.The in vitro drug release efficiency of FA-Dex-b-PPS-Dox was explored by simulating the p H and oxidation conditions of both normal and tumor conditions.4.The killing effect of FA-Dex-b-PPS-Dox on the PC3 cell line was studied through CCK-8 experiments,transwell experiments,and wound healing experiments.Fluorescence staining,confocal laser scanning microscope(CLSM)were used to observe the uptake of Dox,western blot(WB),hematoxylin-eosin(HE)staining,and immunohistochemistry(IHC)staining to analyze the antitumor effects.5.The in vivo anti-tumor effect and drug toxicity of FA-Dex-b-PPS-Dox were studied using mouse xenograft models and experiments such as HE staining and IHC staining.Results1.The validation results of FITR and ~1H NMR indicate that we have successfully prepared the FA-Dex-b-PPS copolymer.2.The results of fluorescence spectroscopy,DLS and TEM show that the morphology of polymer particles is spherical before and after drug loading.After loading,the particle size is about 130 nm in simulated body conditions,which is significantly larger than the 101 nm before loading,indicating that the micelle can successfully load Dox.3.In vitro drug release experiments show that the FA-Dex-b-PPS-Dox micelles have the ability to release Dox triggered by oxidative environment.4.CLSM analysis shows that FA-Dex-b-PPS-Dox can be internalized into PC3cells via FA receptor.In addition,CCK-8 experiment,transwell experiment,wound healing experiment,immunofluorescence staining,WB,HE staining,and IHC staining experiments show that FA-Dex-b-PPS-Dox micelles exhibit good in vitro killing(i.e.anti-tumor)effect on PC3 cells,and prove that they can induce PC3 cell apoptosis by inducing producing ROS.5.In vivo xenograft nude mouse models,HE staining and IHC staining analysis show that FA-Dex-b-PPS-Dox nanoparticles have better anti-tumor effect than Dex-b-PPS-Dox nanoparticles without FA modification,and can reduce the toxic and side effects of Dox compared with traditional Dox.ConclusionThe FA-Dex-b-PPS-Dox block copolymer micelles we successfully prepared have good stability,good ROS response,strong tumor targeting and good anti-tumor effect,which has great potential in the field of nanobiology and tumor-targeted therapy.