Study On New Methods Of Tumor Diagnosis And Treatment Based On Metal Nanoparticles

Tumor is the neoplasm,when the body under a variety of carcinogenic factors,one cell of the local tissue loses its control for normal growth at the genetic level,resulting in abnormal clonal proliferation and the formation of pathologic changes Malignant tumors are easily infiltration and transfer,difficult to radical cure,have high mortality,which is a major disease threatening human health.Early diagnosis and treatment of cancer is of great significance to extend the survival time of patients,improve quality of life and reduce mortality.Although modern medical and diagnostic techniques have improved signifieantly,there are still many shortcomings in the early diagnosis of tumors,leading to some patients have been found in the late period,lost the best time for treatment.Therefore,it is urgent to develop new methods and new principles for tumor diagnosis and treatment,in order to improve the early diagnosis and cure rate of cancer.In recent years,the rapid development of nanotechnology and the cross integration with physical,chemical,biological or other disciplines,Provides a new opportunity for the development of cancer treatment.At present,many new nanomaterial-based detection methods have been proposed with high sensitivity and specificity.However,there are still few methods that can be tested in cells.Real-time and in situ detection of intracellular biomolecules is not only important for basic research on tumor biology,but also in providing new methods for tumor diagnosis.Therefore,it is necessary to develop intracellular biosensors.In addition,the existing tumor treatment drugs are usually less targeted,have certain lethality for normal cells,the side effects are evident and easy to drug resistance.The development of targeted nano-drugs with nanomaterials as the substrate will open up new avenues for the treatment of tumors.In this paper,with metal nano-materials as carrier,development of the detection for tumor markers and targeted anti-tumor cells will provide a new way of thinking for the diagnosis and treatment of cancerChapter 1:A new method for the detection of telomerase based on gold nanoparticlesIn this chapter,we constructed a new method for the detection of cellular telomerase activity based on gold nanoparticles.The telomerase activity assay probe was prepared by modifying the telomerase primer sequence and the signal sequence on the surface of gold nanoparticles.Through endocytosis,the probe get into the cell,when encountered with active telomerase,the end of primer sequence can be extended with numerous of repeated telomere sequence,and then complementary pairing with the stem structure of surrounding signal sequence.The stem loop is opened so that the fluorescent group modified at the 5'end can move away from the surface of the gold nanoparticle and then fluorescence is recovered.The telomerase activity can be characterized by detecting the fluorescence value.In addition,based on the same terminal extension principle,we have designed a biosensor that can detect nucleic acid fragments in vitro.Through a series of experiments,it is proved that the above two similar sensors both have good detection performance in detecting intracellular telomerase activity and nucleic acid in solution.This will provide a new method for sensitive detection of telomerase which is a broad-spectrum tumor marker and tumor-associated nucleic acid fragments,and have the potential to develop early diagnostic methods for tumorsChapter 2:A new method for detecting mRNA in tumor cells based on liquid metal nanopartidesIn this chapter,we constructed a new method for the detection of mRNA in tumor cells,which is based on liquid metal gallium indium alloy nanoparticles.The double-strand DNA is modified with fluorescent groups and fluorescence quenching molecules on each strand,and self-assembly on the surface of gallium indium alloy nanoparticles to form the detection probe.In the weak acid environment of endosome,the accumulation of gallium indium alloy made the double-strand DNA gradually released.When met with the target mRNA.the competitive binding of mRNA and one DNA strand lead to the free of the short DNA strand labeled with fluorescence groups,the detection of target mRNA can be achieved through detection of fluorescence values.After a certain period of time,the alloy will be metabolized by cells.So this nano-probe can detect mRNA quickly and easily both in vivo and in vitro.Because of its biodegradability,it will not produce cell toxicity even in vivo test,thus provide a new way for in vivo detection and real-time monitoring of tumor in the futureChapter 3:A new method for the treatment of cancer based on aptamer and protease co-modified gold nanopartidesIn this chapter,we designed and prepared an aptamer-based targeted protease nano-complex that binds to the highly expressed MUC1 protein on the tumor cell membrane through the MUC1 aptamer and pulls the MUC1 protein closer to the nano-complex,so that the membrane protein get close to the proteinase K modified on gold nanoparticles,leading to the hydrolyzed of surrounding membrane protein The combination of membrane protein and aptamer becomes loose after hydrolysis,and because of the fluidity of cell membrane,the nano-complex can seek and bind the next MUC1 membrane protein,repeating the process until most of the protein on the surface of the cell membrane is destroyed.This process lead to the gradually destruction of protein on the cell membrane,the material metabolism,information exchange and barrier ninction of cell membrane are destroyed,and ultimately cause cell death.After a series of experiments,we confirmed that the nano-complex have high tumor cell targeting and low cytotoxicity,and have the potential to develop into antitumor drug,which provides a new idea for tumor therapy.