| Stomach cancer is the second common cancer in China. Its mortality is the third. Itremains very difficult to cure effectively, primarily because most patients present withadvanced diseases. Its five-year survival rate is less than25%. How to develop one kind ofeffective, simple, early screening technology, to realize the goal of decreasing morbidityand death rate, to realize early diagnosis and therapy of gastric cancer, has become ourconcerns. The analysis of exhaled breath is regarded as a sample and noninvasivediagnosis method, because the volatile organic compounds in the breath exists the closerelationship with the diseases. Therefore, the kinds and quantification of volatile organiccompounds (VOCs) from patients with gstric cancer can reflect the progress of gastriccancer.Up to date, few report is closely associated with the volatile organic compounds(VOCs) of the stomach cancer. In this work, we identified the VOCs biomarkers fromstomach cancer cells and the breath gas of patients with gastric cancer by using GC-MS.Furthermore, we used chlorophyll as bilogical template to synthetize Au and Au-Ag alloynanoparticles in a green synthesis route. The MWNTs/Au-Ag alloy nanocomposites wasprepared and used to modify electrode. The MWNTs/Au-Ag nanocomposites was used tomodify the GCE, as working electrode, then we investigated the effects of differentworking electrodes on electrochemical catalysis ability of MWNTs/Au-Ag sensitive films.The whole dissertation was composed of six chapters:Chapter1: The situation of cancer incidence and mortality in the world and morbidityand mortality statistics of the top10cancers in China were reviewed. The methods usedfor diagnosis of gastric cancer were listed. Meanwhile, the analysis and application ofvolatile organic compounds released by cancer cells and exhaled breath of patients withcancers were introduced.Chapter2: The volatile biomarkers associated with gastric cancer cells weredeterminated by HS-SPME/GC-MS. Muti-wall carbon nanotubes decorated withnanosized Au-Ag alloy, as sensing interface of electrode, was used for ultrasensitivedetection of volatile biomarkers of gastric cancer. The sample preparation approaches and head space solide phase micro-extraction conditions were optimized for screening volatilebiomarkers. Volatiles emitted from the headspace of the cells/medium culture wereidentified. The Au-Ag/multiwalled carbon nnaotubes were prepared as a electrochemicalsensing interface for detection of volatile biomarkers.Chapter3: Reported an one-pot, environmentally friendly method for biosynthesizingAu-Ag alloy using chloroplasts as reducers and stabilizers. The prepared Au-Ag alloy wasdispersed into the surface of multiwalled carbon nanotubes (MWNTs) to form ananosensing film. The electrocatalytic activity of the nanosensing film toward butanonewas investigated at room temperature.Chapter4: A new method of one-pot biosynthesizing of gold nanoparticles usingchloroplasts as reductants and stabilizers was reported. The cytotoxicity of the goldnanoparticles was evaluated. Rhodamine6G as a Raman probe was used for investigatingsurface-enhanced Raman spectroscopy of as-prepared gold nanoparticles.Chapter5: The volatile metabolites excreted by MGC-803gastric cancer cell line andpatients with gastric cancer were investigated. Solid phase microextraction (SPME) wasused for pre-concentrating of volatile organic compounds (VOCs) in the cell samples andbreath samples. The analysis of VOCs was accomplished by gas chromatography coupledwith mass spectrometry (GC-MS).volatiles emmitted by both cells and patients withgastric cancer were determinated.Chapter6: Gave a summary and prospects of current research work. |
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