Application Of Multi-functional Nanoparticles In SERS Detection And Precise Therapy Of Cancer

Up to now,cancer is still a leading cause of mortality worldwide,so to cure cancer has been an urgent task.Though traditional therapeutic methods,such as surgery,chemotherapy and radiotherapy,can effectively kill tumor cells and inhibit the tumor metastasis,the cure rate of cancer is still very low.The main reasons maybe are as follows: the fail of inchoate diagnosis of cancer;the targeting of small molecule drugs is poor;the mechanism of cancer occurrence is indistinct or the decline in drug efficacy caused by drug resistance of cancer cells.Therefore,to improve the survival rate of cancer patients,the development of new diagnostic and treatment methods is essential.With the development of nanotechnology,nanomedicine has become a powerful weapon for precision medicine.An increasing number of novel therapeutic concept and methods have been applied to the diagnosis and treatment of cancer.While as the key components of nanomedicine,nanoparticles are greatly developed and exploited as the emerging platform for their applications in cancer nanomedicine.In this thesis,based on the above difficulties exist in the process of cancer treatment,we developed two ultrasensitive SERS nanoparticles and two novel nanodrug delivery systems for the early diagnosis of cancer,revealing the real-time action mechanism of targeted complex drug to cancer cells,overcoming the drug resistance of leukemia cells and achieving precision treatment of leukemia by regulating the expression of abnormal genes in the epigenetic pathway.The main research content is as follows:1.Sialic acid has been an important biomarker for the early diagnosis of cancer owing its overexpression on the surface of cancer cells.To significantly amplify the difference of sialic acid expression level on the surface of cancer cells and normal cells,herein,based on specific affinity between sialic acid and 4-mercaptophenyl boronic acid(MPBA),a low cytotoxicity and highly sensitive surface-enhanced Raman scattering(SERS)nanoprobe(glucose-MPBA@Ag NPs)was prepared by inducing controllable assembly of MPBA decorated Ag nanoparticles(MPBA@Ag NPs)in a certain level via the bridge of glucose for the targeted recognition of cancer cells.Compared to the monodisperse MPBA@Ag NPs,the SERS enhancement ability of the assembly increased 10 times.And more important,assembled glucose-MPBA@Ag NPs enlarged the difference of sialic acid expression to 5-7 times,improved the sensitivity of cancer cell detection and provided a new method for the early diagnosis of tumor.2.Whether the anticancer drugs could reach the tumor region successfully determines the therapeutic efficacy of drugs.Now,to reduce the baneful adverse reaction of the drug,plenty of targeted vectors have been applied for the delivery of small molecule drugs.However,the mechanism of drugs inside of the vectors during the sustained release process has not been studied yet.In this part,firstly,we prepared the targeted aptamer/drug conjugate(TLS11a-GC-Dox),and then real-time traced the therapeutic process by the surface-enhanced Raman scattering(SERS)spectroscopic technique and dark-field imaging with the assistance of nuclear targeted SERS probes.Through analyzing the changes of SERS spectra of the biological molecules in the nucleus,we infered that along with the Dox release,the structure of relevant proteins and DNA in the nucleus changed significantly,which affected cell dividing and proliferation.This is the first time analysing the action of targeted complex drugs in the molecular level.3.Epigenetic aberrance is the main cause of leukemia.By analyzing the expression level of mi RNA in AML cells,we find that mi R-221 is overexpressed and involved in the epigenetic pathways-NCL/mi R-221/NF?B/DNMT1,which is considered as a new molecular pathway promoting aggressive acute myeloid leukemia(AML)leukemogenesis.Based on this mechanism,we prepared a novel nuclear localization signal(NLS)peptide-functionalized gold nanoparticle,which have been used as a nanoplatform to co-deliver two anticancer agents AS1411 and anti-221 for the regulating of NCL/mi R-221/NF?B/DNMT1.AS1411 and anti-221 can inhibit the overexpression of NCL and mi RNA along with the activation of p27kip1 and p15ink4 b,and remarkably blockaged the leukemia proliferation.In vivo experiments also proved that AS1411 and anti-221 can synergistically suppress AML cell growth via targeting key molecules involved in NCL/mi R-221/NFk B/DNMT1 pathway.In a word,our results demonstrated that nano-drug delivery systems can achieve accurate treatment of leukemia cells by regulating the epigenetic pathways.4.Resistance to chemotherapy and molecularly targeted therapies is a major problem facing current leukemia therapy.Here,we demonstrated that there is a mi R-221 network cross-talk with P-glycoprotein(P-gp)specific activation in drug resistant leukemia cells induced by doxorubicin.Based on this,multifunctional gold nanoparticles were designed and synthesized to co-deliver three anticancer agents,AS1411,doxorubicin and anti-221 for overcoming the drug resistance and improving the treatment efficacy.Decreased resistant cell growth induced by these nanoparticles was associated with a marked downregulation of mi R-221,DNMT leading to restoration of tumor suppressor p27kip1 and p15ink4 b,as well as decrease mi R-221-mediated P-gp expression.Finally,the treatment of primary blasts of leukemia patients with chemoresistant relapse by these nanoparticles sensitized cells to doxorubicin treatment,evidenced by leukemia cells suppression with significant decrease IC50 of doxorubicin,which means novel drug delivery system can precisely reverse multidrug resistant leukemia in preclinical models of leukemia.