Construction And Evaluation Of An Oxidative Stress Nanodrug Delivery System Based On The Function Of Open Source And Reduce Expenditure

As the second leading cause of human death,tumor therapy has always faced many challenges in cancer treatment.Compared with normal cells,tumor cells are at an abnormal state of oxidative stress due to their own genetic and metabolic factors,making them more vulnerable to additional reactive oxygen species（ROS）attack.Therefore,the strategy of exacerbating intracellular oxidative stress by increasing the extracellular ROS level was expected to provide certain research value in tumor oxidative therapy.However,ROS-mediated tumor therapy,such as chemodynamic therapy（CDT）,has been limited in the clinical tumor treatment due to the low hydrogen peroxide（H₂O₂）level in cancer cells and the lack of endogenous ferrous ions with high catalytic activity.Therefore,we designed an oxidative stress nanoamplifier drug delivery system based on the strategy of open source and reduce expenditure,simultaneously increasing highly reactive ROS generation to realize the purpose of“open source”and depleting the intracellular GSH levelto realize the purpose of“reduce expenditure”,finally synergistically enhances oxidative stress to induce tumor cells death.In this paper,we designed a passive tumor-targeting nanoscale coordination polymer（NCP）based on Iron chloride hexahydrate（Fe）,Fenton reaction catalyst and GSH inhibitorβ-phenethyl isocyanatosulfate（PEITC）.coordination polymer,NCP).Firstly,by using the reverse microemulsion method,Fe³⁺and Sk were chosen as the organic ligand to fabricate the Sk-Fe@DOPA,and then coated with phospholipid in the surface to form the shell of Sk-Fe@DOPA,where the GSH inhibitor PEITC was loaded to prepare the multifunctional coordination nanoparticle polymer（Sk-Fe@PEITC）.The morphology,elemental composition and particle size potential of the coordination nanoparticles were determined by TEM,EDS,FT-IR.The results showed that the prepared particles exhibited uniform spherical nanoparticles with a particle size of 55 nm,which had good dispersibility,stability,and negatively charged.The properties of Sk-Fe@PEITC were investigated by Fenton catalyst capacity and in vitro release,respectively.The results showed that Sk-Fe@PEITC with strong Fenton catalyst capacity could convert the low-activity H₂O₂into highly toxic·OH through Fenton reaction.Moreover,the in vitro release experiment results indicated that the drug released from Sk-Fe@PEITC could be the most at p H 5.0.Using 4T1 cancer cells,the cellular uptake,cytotoxicity,ROS production capacity,·OH production capacity,GSH consumption and apoptosis of Sk-Fe@PEITC nanoparticles were investigated.The cellular uptake results showed that the cell uptake of Sk-Fe@PEITC reached equilibrium at 4 h.In the cytotoxicity experiment,the results proved that Sk-Fe@PEITC had the strongest killing ability by MTT method and live and dead cell staining.In addition,the ROS generation ability,·OH generation ability and GSH consumption experiments indicated that Sk-Fe@PEITC could induce tumor cells to produce higher levels of ROS（H₂O₂）directly to kill tumor cells directly,and then the higher H₂O₂level could be converted into highly toxic·OH via Fenton reaction with the catalyst of Fe,which further enhanced the killing effect in tumor cancers and realized the purpose of"open source"effect of ROS.Meanwhile,PEITC could consume intracellular GSH to weaken the antioxidant system and inhibit the elimination of ROS indirectly,so as to realize the purpose of"reduce expenditure"effect of ROS.Under the dual mechanisms of"open source"and"reduce expenditure"of ROS,the ROS generation could enhance extracellular oxidative stress to induce tumor cancers apoptosis.The inhibitory effect of the coordination particle Sk-Fe@PEITC in tumor cancers was investigated using 4T1 cells bearing BALB/C mice model.The in vivo distribution results showed that the nanoparticles could passively target into the tumor site through the EPR effect and accumulatie perferentially into the effective site of the tumor.The in vivo efficacy results indicated that the nanoparticles can synergistically amplify intracellular oxidative stress through Sk,Fe³⁺and PEITC to achieve the strongest tumor suppressive effect.The pathological tissue sections and blood biochemical indexes of tumor-bearing mice showed that Sk-Fe@PEITC had no obvious toxic and side effects on the important organs of mice with good biological safety.In conclusion,in this paper,we designed an oxidative stress nanoamplifier of"opening source and reducing expenditure",the co-delivery of ROS generation Sk,GSH scavenger PEITC and catalyst Fe³⁺to amplify oxidative stress for synergistic chemotherapy/chemodynamic therapy of tumor.Therefore,the nanoparticles not only provides great research value in tumor therapy,but also exhibites the great potential of natural products in the field of tumor therapy,opening a new therapeutic window for ROS-mediated tumor therapy in the future.