Construction Of Activatable Nano-drug Delivery System And Its Anti-tumor Application Research

The development of new medical cancer treatment technologies is of great significance in reducing cancer mortality.Traditional clinical cancer therapy has a short drug action time,difficulty in accurately targeting tumor tissues and high levels of toxicity in normal tissues.With the development of nanotechnology,nanomaterials have been used as drug carriers to specifically target cancer cells and release drugs into the tumor environment.This technique has become an important research hotspot in cancer treatment.Using nanomaterials as drug carriers for cancer treatment can improve the efficacy of drug delivery,including increasing drug concentrations in target tumor areas,reducing toxicity in normal tissues and controlling drug release.With the rapid development of nanotechnology in biological and medical research,more and more problems have emerged in practical applications,such as tissue penetration,cycle time,toxicity,solubility,immunogenicity,etc.The practical task of studying drug delivery systems is to effectively treat cancer while causing minimal harm to patients.Based on the problem of nanoparticle drug transport in cancer treatment,three drug delivery systems: p Hresponsive renal clearance nanodrug carrier system,PEG-DOX micelle nanodrug carrier system and ferritin nanodrug carrier system,were designed,and their effects in cancer treatment were studied by cell or mouse models.The specific research contents are as follows:1.The anticancer drug Adriamycin(DOX)was attached to PEGylated gold nanoparticles(Au NPs)by the acid-responsive linker 3-(2-pyridyl dithiophenyl)propionyl hydrazine(PDPH)to construct a renal-clearable p H/GSH dual-response drug delivery system Au-DOX.Firstly,the successful synthesis of Au-DOX was demonstrated by TEM,UV-Vis absorption spectroscopy,and agarose gel electrophoresis.In vitro stability studies and drug release experiments have shown that PDPH linkers can break and release DOX under acidic p H conditions,the drug release rate at 48 h was 46.2%.In addition,Glutathione(GSH)can also release DOX through thiol exchange reaction.In vivo experiments in mice showed that AuDOX nanoparticles were aggregated 2.3 times more than DOX at the tumor,because PEGylation greatly extended the blood circulation time of the drug.However,the tumor inhibition effect was not obvious,the tumor volume of the Au-DOX treatment group was almost twice that of the DOX group at the same dose,which can achieve a similar therapeutic effect as the DOX group when increasing the frequency of administration.Further cell experiments showed that the nanoparticles were easily encapsulated by lysosomes after entering the cell,so the drug delivery effect was inhibited to a certain extent.Biodistribution and pathological analysis in organs showed that most of Au-DOX was concentrated in tumors after multiple administrations,and had no toxicity to liver or kidney.In addition,Au-DOX can be metabolized by the kidney,and 47% of the drugs were excreted through urine within24 h,indicating that it has high biological safety.The low toxicity of Au-DOX can also be concluded through the analysis of renal function test.The above results show that in the rapid development of renal-clearable nanocarriers today,renal-clearable materials do have unique advantages in improving targeting and safety,but drug delivery is not only to deliver drugs to the tumor area,the release in the tumor area and the real play of efficacy are also the key considerations for the development of renal-clearable carriers.2.PEG-DOX micellar nanoparticles were prepared by using m PEG-SH(5 K)as the hydrophilic end and DOX as the hydrophobic end in a ratio of 2:1.PDPH linker was used between the hydrophilic end and the hydrophobic end.The pyridine dithiol at one end of PDPH reacts with the m PEG-SH free sulfhydryl group to form a disulfide bond,and the hydrazine group at the other end reacts with the carbonyl group of DOX to form a stable hydrazone bond.TEM demonstrated our successful synthesis of spherical micellar nanoparticles PEG-DOX with a size of about 35 nm.In vitro stability studies and drug release experiments showed that PDPH could break and release DOX under acidic p H conditions,and the release efficiency was 67.6%.Cell fluorescence imaging and cytotoxicity experiments have shown that PEG-DOX can be endocytosed into cells and slowly release drugs to kill cells.At a concentration of 100 μg/m L(approximately 1/8 of the administered concentration),the cell viability was 42.8% after 24 h.We used a 4T1 mouse subcutaneous tumor model to evaluate the therapeutic effect of PEG-DOX,after intravenous administration,the PEG-DOX group showed the slowest growth in tumor volume compared with the PBS group and the free DOX group,demonstrating effective tumor inhibition.This PEG-coated micellar nanoparticle raw material is simple and easy to synthesize,and has a good application prospect.3.Based on natural horse ferritin(Ftn)as the nanocarrier,a novel nanoparticle Ftn-AuICG for the synergistic treatment of photothermal and oxidative stress was synthesized by synthesizing gold nanoparticles on its surface and the fluorescent molecule indocyanine green(ICG)was modified with amino group on the surface.In vitro fluorescence experiments have shown that gold nanospheres bonded on the surface of ferritin nanoparticles have the ability to consume GSH.In vitro photothermal conversion experiments showed that 1.5 mg/m L FtnAu-ICG could reach 70°C after 10 min of illumination,which had good photothermal effects.Cell fluorescence imaging showed that Ftn-Au-ICG can enter the interior of cells through lysosomal endocytosis.Cell death was determined by PBS,Ftn-Au(light)and Ftn-Au-ICG(light,no light,four times of light).The experimental results showed that Ftn-Au-ICG had the strongest killing effect on cancer cells after passing light,and 95% of the cells showed death after four irradiations.It shows that Ftn-Au-ICG can be used as a drug for cancer treatment.