Construction Of Glucose Oxidase-loaded PCN Nanosystems And Their Study In Tumor Combination Therapy

Tumor is a major killer that threatens human health.Traditional treatment methods such as surgery,chemotherapy and radiotherapy suffer from poor efficacy,side effects and the tendency to metastasise and recur,and there is an urgent need to develop new treatment methods with fewer side effects.New nanomaterial-based treatments（e.g.,photodynamic therapy,starvation therapy,chemodynamic therapy,etc.）have overcome the shortcomings of traditional treatment methods.However,clinical practice has shown that single treatments still do not achieve good results.In order to improve the effect of photodynamic,starvation and chemodynamic therapy,this paper designed two new nano-loaded drug delivery systems（PCN-224-GOD@HA and PCN-224-Pt/GOD@MnO₂）for combined tumor therapy using Zr⁴⁺base metal organic backbone material（MOF）PCN-224 nanoparticles as carriers and loaded with glucose oxidase.The content and results are as follows:（1）Synthesis and characterization of PCN-224 nanoparticles loaded with glucose oxidase.The Zr⁴⁺-based MOF material（PCN-224）was prepared using a solvothermal method,and the SEM results showed that its particle size was about 100 nm.PCN-224-GOD was then prepared by coupling glucose oxidase（GOD）on the surface of PCN-224 with 1-ethyl-（3-dimethylaminopropyl）carbodiimide（EDC）,and further modified with hyaluronic acid to improve the water solubility and stability of PCN-The successful synthesis of P-GOD@HA was verified by SEM,UV-Vis spectrophotometry,FTIR and zeta potential characterisation experiments.size was about 140 nm,which was consistent with the DLS characterization results.In vitro reactive oxygen species assays showed that P-GOD@HA is capable of producing reactive oxygen species under light conditions.The results of cytotoxicity assay showed that the combination therapy based on P-GOD@HA could effectively inhibit the proliferation of tumor cells with an inhibition rate of 70%,and the results of CCK-8 assay showed that P-GOD@HA had almost no harm to normal mouse cells（MEF）and had good biosafety.（2）Preparation,characterization and antitumor activity study of PCN-224-Pt/GOD@MnO₂.The hypoxic environment caused by GOD-induced glucose oxidation in P-GOD@HA inhibits the therapeutic effect of photodynamic therapy,but the pH reduction and H₂O₂ elevation caused by the oxidation products gluconate and H₂O₂ can trigger chemodynamic therapy based on Fenton/Fenton-like reactions.Therefore,PCN-224-Pt/GOD@MnO₂（P-P/GOD@M）nanoparticles were further prepared for combined starvation-chemo-kinetic therapy of tumors.PCN-224-Pt/GOD@MnO₂（P-P/GOD@M）was prepared by reducing platinum nanoparticles on the surface of PCN-224 by redox,then coupling glucose oxidase with PCN-224-Pt using EDC to synthesize PCN-224-Pt/GOD,and finally wrapping MnO₂ in its outer layer by redox.SEM The results show that the size of P-P/GOD@M is about 280 nm;the characterisation results such as UV-Vis spectrophotometer,FTIR and zeta potential indicate the successful synthesis of the material.In an acidic environment mimicking a tumor microenvironment（TME）,MnO₂ was able to deplete glutathione（GSH）and release GOD and Pt.The oxidation of glucose by GOD to produce gluconic acid reduced the pH of the solution from 5.5 to 3.8,increasing the H₂O₂ content and enhancing the chemokinetic（CDT）efficacy.In vitro cellular experiments showed that P-P/GOD@M was more effective in tumor inhibition than GOD alone,increasing the inhibition of MCF-7 cells from57%to 80%,indicating that the combined starvation-chemo-kinetic treatment was more effective than single starvation treatment.Experiments on mice showed that after 14 days of treatment,the tumor weight of the P-P/GOD@M group was 0.154 g,which was significantly lower than that of the blank group（1.345 g）,indicating that P-P/GOD@M could effectively inhibit the growth of tumor cells in tumor-bearing mice and prolong the survival time of mice from about 18 days to 40 days.HE sections showed that P-P/GOD@M nanomaterials were more effective on HE sections showed that the P-P/GOD@M nanomaterials were not harmful to the major organs of mice（heart,liver,spleen,lung and kidney）and had a good biosafety profile.In summary,two nanomaterials,P-GOD@HA and P-P/GOD@M,were designed in this study.The successful synthesis of both nanomaterials was demonstrated by electron microscopy,UV,IR and DLS characterisation methods.Cell uptake assays showed that both nanomaterials could be taken up by cells,and cytotoxicity assays showed that both nanomaterials could effectively inhibit the proliferation of tumor cells.Mouse experiments showed that the P-P/GOD@M nanomaterials could inhibit tumor growth and prolong survival time in mice.Thus,the PCN nanomaterials loaded with glucose oxidase constructed in this paper have some reference significance for clinical applications.