Construction And Application Of Integrated Nanoprobe In Tumor Diagnosis And Treatment

With the extensive interdisciplinary of nanotechnology and biomedical field,nanotechnology has shown great advantages in cancer prevention,early diagnosis,imaging and treatment.Nano materials have been widely used as new composite probes for tumor therapy because of their multi-function,easy preparation,high biocompatibility surface modification and high stability.The special properties of nanostructures,such as sound,light,electricity,heat and magnetism,have been used to improve cancer detection in vitro,imaging in vivo and targeted drug delivery and treatment.Based on this,X-ray computed tomography/fluorescence dual-function contrast agent with complementary advantages was designed and prepared;photothermal and photodynamic therapy,"starvation therapy"and chemodynamic therapy for promoting photothermal therapy were prepared by using tumor microenvironment and endogenous molecules,and nano drug platform for integration of early diagnosis and treatment diagnosis of tumor was designed and prepared.The main research results are as follows:(1)In this paper,gold nanorod and InP/ZnS quantum dot were encapsulated together in the silica medium,and the targeting molecular peptide c(RGDf C)was further connected after the surface modification of PEG and PEG derivatives to prepare the multifunctional Au@QD@Si O₂/PEG-c(RGDf C)probe.In vitro experiments showed that the probe size was about 215.01±2.72 nm,and the dispersibility was good.When the concentration was as high as 200?g/m L,the activity of cell was still 85%due to low toxicity.In vivo experiments showed that the probe had excellent tumor targeting X-ray computed tomography(CT)imaging and fluorescence imaging capabilities.The experiments revealed that the probe had a long blood circulation time(T_1/2=7.78 h)in mice;biochemical analysis,liver enzyme analysis and histomorphological analysis after probe injection showed that the probe had no obvious side effect to the normal function of main organs,indicating good biosafety.In vivo imaging experiments showed that after 6 d of intravenous injection,the tumor site of He La tumor-bearing nude mice positive group presented obvious fluorescence and CT signals,indicating that the prepared nanoprobe had good tumor targeting dual-mode imaging capabilities and therefore showed a greater potential in biomedical imaging application,especially the diagnosis of cancer.(2)Photodynamic therapy(PDT)is an important means of cancer treatment.In this paper,an intelligent multifunctional nanoprobe is prepared using gold nanostar with high thermal conversion efficiency as the core,photosensitizer Ce6-loaded mesoporous silicon as the shell,then modified by catalase(E)and encapsulated by phospholipid derivative with c(RGDy K)targeting molecule.The probe size is about 180 nm,and it has good dispersion and stability,and the photothermal conversion efficiency is as high as 28%.At the same time,the probe has photodynamic"on-off"effect on Ce6 encapsulated in mesoporous channels.The ¹O ₂probe and cell experiments show that the probe can trigger the"release"of Ce6 only under the photothermal action.After 660 nm irradiation,free Ce6 can produce a large amount of singlet ¹O₂.Therefore,it can significantly inhibit the non-specific phototoxicity.At the same time,catalase carried by probe can catalyze hydrogen peroxide in the tumor site to generate oxygen,which alleviate the hypoxia of tumor site and improve the photodynamic treatment effect.Animal experiments show that72 h after injection of the probe,the lesion site of the tumor-bearing mice showed obvious CT response.Tumor volume,mice weight,hematoxylin-eosin staining and immunohistochemical staining confirmed that the combined treatment of photothermal therapy(PTT)and catalase-assisted photocontrolled(PDT)present better effect than the single PTT or PDT significantly for tumor,and can improve the therapeutic effect availably,and overcome the hypoxic resistance of PDT.The biochemical index experiments show that the probe has good biological safety.This work has important reference value for exploring new photodynamic probe.(3)Multi-mode combination therapy for tumors would have better therapeutic effect than monotherapy.Based on this,we designed a super-small polyvinylpyrrolidone protected bismuth/copper-gallic acid coordination polymer nanoparticle,which was co-encapsulated with glucose oxidase in the phospholipid and to be used for the Chemodynamic therapy(CDT)enhanced by combination of photothermal therapy(PTT)and starvation(ST).The results exhibited that the average particle size was 1.8±0.7 nm,and the photothermal conversion efficiency was 31.35%after the particles coated with phospholipidthe,so the probe could be used as photothermal imaging and photothermal treatment reagent.The probe was injected into tumor-bearing mice by the tail vein after12 h,which was enriched in the tumor effectively,and then gradually excreted through urine,indicating that the probe had good biological safety.In the treatment process,glucose oxidase consumed oxygen and glucose of the tumor tissue through biological catalysis to generate glucose acid and hydrogen peroxide(H₂O₂).Hydrogen peroxide reacted with copper ions(Cu²⁺)to produce stronger toxicity hydroxyl radicals(·OH)and oxygen,which was supplied to the glucose oxidase catalysis,avoiding the restriction to catalysis because of tumor hypoxia.The two complementary reactions increased glucose consumption,decreased heat shock protein expression,enhanced the tumor sensitivity to low temperature PTT mediated by nanoparticle,and directly inhibited tumor growth,improving the PTT efficacy of Bi³⁺.In vitro and in vivo experiments indicated that the combined approach had the best therapeutic effect,tumor growth was obviously inhibited.This nanoplatform provided a new avenue for the combination of chemodynamic therapy with other treatments,which had a great significance for the new therapy method.To sum up,based on the versatility of nano metal particles and the special microenvironment of tumor tissue,this paper developed a variety of nano platforms of stimulus response type.Using the endogenous molecules of tumor cells as the raw materials in the treatment process,it is safe and effective for the early diagnosis and treatment of tumor.