| Objective:Malignant tumor has become the major disease of threatening human health,resulting in large mortality rate.At present,the clinically adopted treatment methods have shortcomings such as poor specificity and incomplete treatment,so it is urgent to explore efficient treatment methods.Studies have shown that the cause of poor tumor recovery involves not only endogenous changes in tumor cells,but also changes in the tumor microenvironment（TME）.The tumor microenvironment plays a vital role in the occurrence,development,metastasis,and resistance of tumors.Therefore,it is of great significance to design nanodrugs triggered by the tumor microenvironment according to the characteristics of the tumor microenvironment（such as p H acidity,endogenous H2O2 and GSH overdose,etc.）.Therefore,this paper uses human cervical cancer cells（He La Cells）as a cell model,and designs two nanodrugs to specifically respond to excess GSH and excess H2O2 in TME respectively to achieve efficient treatment of tumors.The main tasks are as follows:1.Molybdenum disulfide（Mo S2）was synthesized,and then manganese dioxide（Mn O2）was wrapped on its surface by redox method,and m PEG-NH2 was modified on its surface by electrostatic action to increase biocompatibility.Mn O2wrapped in the surface produces Mn2+while consuming GSH,and Mn2+is further reacted with H2O2 to generate·OH,forming a nano-diagnosis and treatment system that specifically responds to excess GSH in TME Mo S2@Mn O2-PEG.Then,in vitro simulated TME detects the responsiveness of nanodrugs to excess GSH and detects their photothermal properties（PTT）as well as chemical kinetic properties（CDT）in vitro.Finally,the effects of multimodal imaging and PTT/CDT synergistic therapy at the cellular and in vivo levels of Mo S2@Mn O2-PEG were studied.2.Sheet graphite phase carbon nitride（g-C3N4）was prepared by heat treatment,and pg-C3N4 small nanosheets were obtained by protonation treatment.Then,using atomic layer deposition technology to load zinc oxide（Zn O）on its surface,a pg--C3N4-Zn O heterojunction is formed,and the PEG is wrapped around its surface to increase biocompatibility.The formation of heterojunctions inhibits the recombination of electron hole pairs of pg--C3N4 and improves its catalytic efficiency.At the same time,the prepared pg--C3N4-Zn O has a specific response to the excess H2O2 in TME,and the reactive oxygen species generated under xenon lamp illumination can achieve the effect of killing tumors.Finally,the in vitro properties of pg--C3N4-Zn O were detected and its ability to kill tumor cells was assessed.Methods:1.MoS2 is synthesized with ammonium molybdate as raw material and hydrazine hydrate（80%）as the reducing agent.With KMn O4 as the raw material and dopamine as the reducing agent,Mn O2 was wrapped on the surface of molybdenum disulfide by redox method,and then the biocompatibility of Mn O2 was improved by electrostatic action on the surface of Mn O2 to load PEG,and finally the nano diagnosis and treatment system Mo S2@Mn O2-PEG was successfully prepared.Detection methods such as TEM,SEM,and Zeta potential were used to ensure successful nanosystem preparation;the photothermal performance of Mo S2@Mn O2-PEG was detected by 808 nm laser irradiation,and the CDT performance of Mo S2@Mn O2-PEG was detected by in vitro simulation of GSH excess in TME.Detection cell uptake capacity of Mo S2@Mn O2-PEG by laser confocal microscopy;Mo S2@Mn O2-PEG killing capacity of tumor cells by MTT and Calcein-AM/PI;evaluates Mo S2@Mn O2-PEG multimodal imaging capability at the in vivo level by small animal imaging techniques;and evaluates tumor therapeutic efficacy and biosafety by tumor volume changes,mouse weight changes,histopathological analysis Mo S2@Mn O2-PEG,and H&E staining of major organs.2.Urea as raw material was used to obtain g-C3N4 nanosheets by two heat treatments in muffle furnaces,,and then small particles of carbon nitride are obtained by acidification of hydrochloric acid,and the thickness of the deposited zinc oxide is accurately controlled by controlling the number of cycles by using atomic layer deposition technology.The material was characterized by hydrated particle size and potential,the photodynamic properties of the in vitro mimic tumor microenvironment detected by UV-Visible absorption spectroscopy,and the photodynamic killing ability of nanomedicines on tumor cells by MTT and Calcein-AM/PI staining.Results:1.The successful preparation of nanodrugs was proved by SEM and potential changes;TEM and hydrated particle size showed that nanodrugs had good dispersion;photothermal property detection and in vitro chemical kinetics detection proved that nanodrug had good properties;nanodrug had good killing ability on tumor cells at the cellular level;living level research results showed that nanodrugs had good inhibitory effect on living tumors and could provide MR,CT and photothermal trimodal imaging modes.2.The hydration particle size and potential changes proved the success of the preparation of the material;in vitro detection results showed that the maximum amount of reactive oxygen species produced when depositing five cycles of zinc oxide on the surface of carbon nitride,and the photodynamic therapy effect was the best;at the cellular level,it was proved that nanodrug have good killing ability to tumor cells.Conclusion:The first part of this paper successfully prepared a Mo S2@Mn O2-PEG nano-theranostics system,which has PTI,MRI,CT multimodal imaging and PTT/CDT synergistic therapeutic effects,and applied it to organisms.It was proved in vitro that the nano-diagnosis and treatment system had good PTT and CDT properties.Cell experiments have proved that Mo S2@Mn O2-PEG is less toxic to normal cells and has strong lethality to tumor cells,indicating that Mo S2@Mn O2-PEG has excellent anti-tumor properties.Moreover,PTI,MRI,CT proved that Mo S2@Mn O2-PEG has the function of multimodal imaging,and in vitro experiments in animals have also shown that the Mo S2@Mn O2-PEG has good biosafety,and has a good therapeutic effect on tumor-bearing mice.The second part of this paper uses the advantages of ALD to prepare pg-C3N4-Zn O nanodrugs that are responsive to excess H2O2 in the tumor microenvironment,and accurately controls the Zn O loading amount deposited on the surface of pg-C3N4 by atomic layer deposition technology to inhibit the compounding of electron hole pairs of pg-C3N4.The results show that when Zn O with 5 cycles is deposited on the surface of pg-C3N4,the electron hole pairs that inhibit pg-C3N4 have the highest composite,produce the most reactive oxygen species,have the strongest tumor lethality,and have the best treatment effect.The nanodrug exhibits good PDT effect at the cellular level and has good biosafety without xenon lamp irradiation. |
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