Construction Of Functionalized Probe Based On QDs And Its Discrimination For Lung Cancer Marker

The morbidity and mortality of lung cancer in our country has been increasing caused by the environmental pollution, and it has become a serious threat to human health even life. Due to its early symptom is not apparent, 70% of the patients with lung cancer are diagnosed with locally adanced and lost the operation chance due to lack of effective therapy. While the 5-year survival rate of lung cancer patients with early diagnosis is as high as 80%. Therefore, early diagnosis is very important to the survival rates of patients with lung cancer. At present, there are many problems in the routine screening method of lung cancer such as trauma and high cost etc. With the constant development of molecular biology and immunology, tumor markers(TM) play more and more important roles in tumor screening, diagnosis, prognosis and evaluating effects. So the sensitive and specific recognition and detection of the cancer markers has important clinical significance inthe early diagnosis, therapy and tumor metastasis.In recent years, the fluorescent nanoprobe has been widely used in the research of biochemical process, diagnosis and monitoring of disease markers and detection of harmful compounds because of its sensitivity and easy operation, etc. However, most of the fluorescent nanoprobes used in cell imaging are “always-on” fluorescent, which can lead to a false positive due to the nonspecific adsorption of the always-on nanoprobe on the surface of nontarget cells and the fluorescence “always-on” probe needs many washing operations for accurate imaging of cells and is not favorable to afford high signal/background ratio. In addition, the single signal detection and the single target recognition is easy to produce false positive results, this is because the growth of cancer is not only related to whether the expression of tumor markers, but also to the expression level of a variety of specific markers within the tumor cells. In order to solve these problems, the fluorescent "turn-on" probe has attracted more and more attention. Based on the the functionalized QDS combined with fluorescence imaging, the specific small molecule and aptamer as recognition unitand quantum dots as a sensing signal, the probe is applied to identify lung cancer markers and lung cancer cell fluorescence imaging. The probe is expected to provide a new tooland important scientific basis for the diagnosis and prognosis of lung cancer. At the same time, the double signals of fluorescence and resonance light scattering of used for detection of ProGRP in lung cancer cell metabolism and the liquid array based on different quantum dots was constructed to get more accurate results for the biomarker. The lung cancer markers as test object, the quantum dots probes were constructed for the qualitative identification and quantitative detection of biomarker by using fluorescence imange, resonance light scattering, fluorescence, phosphorescence and sensorarray. It is expected to provide an important scientific basis for early diagnosis and prognosis of lung cancer. The main contents of paper are as follows:(1) Designed and synthesized a "turn-on" the fluorescence probe with folic acid(FA) as functional molecule, mesoporous silica nanometer materials coated CdTe quantum dots(CdTe/MSNs) as sensor signal for the recognition of lung cancer cells from normal cells.The fluorescence quenching of CdTe/MSNs by folic acid provides the low background interference. The fluorescence "turn-on" the response to the folate receptor(FR) is based on the change of the acidic environment inside and outside the lung cancer cells and high affinity of FA with FR in the cell, leading to CdTe/MSNs released from probe and the fluorescence recovery. The morphology and surface groups of CdTe/MSNs was characterized by TEM and IR spectra, respectively.The results show that the CdTe/MSNs is homogeneous spherical, its average particle size is less than 100 nm and mesoporous materials are successfully modified on the surface of quantum dots. The adsorption properties, selectivity, stability and the cytotoxicity of CdTe/MSNs were studied. The results show that CdTe/MSNs have good adsorption performance and selectivityto FA because of folic acid containing carboxyl groups, which can combine with the amino groups on the surface of quantum dots and functional monomer by electrostatic effect; and the matching effect of different hole cavity in mesoporous materials to the different molecular structure and volume, the identification of mesoporous materials hole cavity matching function.The influence of acidity provides conditions of folic acid released from CdTe/MSNs within the tumor cells. Mesoporous silica as the coating material, it can prevent the release of toxic components, greatly reduce the cytotoxicity induced by Cd2+. FA- CdTe/MSNs probe targeted imaging has been used in lung cancer cells, the results showed that the FA-CdTe/MSNs can be internalized into A549 cells through the receptor-mediated endocytosis, and is difficult to enter the normal cells for lacking of the targeting receptor of FR. So, the FA functionalized CdTe/MSNs fluorescent probe can provide accurate imaging information for early diagnosis of lung cancer.(2) Constructed a hyaluronan functionalized fluorescent probe based on the noncovalent self-assembly of hyaluronan(HA) and thiolated chitosan(TCS) coated CdTe QDs.The probe can be ued for the identifying and distinguish different types of lung cancer cells owing to the difference in expression level of CD44 glycoprotein, the specific recognition and the combination of CD44 with HA. The living lung cancer cells imaging experiments demonstrate its value in recognizing cell-surface CD44 receptor with turn-on mode. In addition, the western blot experiment further proved the difference of CD44 in lung cancer cells. Therefore, this probe may be potentially applied in recognizing lung cancer cells with higher contrast and sensitivity and provide new tools for cancer prognosis and therapy.(3) The target recognition probe of Apt- Mn: ZnS QDs was constructed by using aptamer as recognition moleculebased on its high affinity and high specificity, easy synthesis, excellent reproducibility, flexibly modification and convenient reserve. The probe has been applied to detecting the small cell carcinoma marker ProGRP by using the phosphorescence and resonance light scattering signal in the optimized reaction conditions. Apt- Mn: ZnS QDs probe exhibited a highly selective response to ProGRP and showed a very good linearity in the range of 1.2- 30.0 ng·ml-1with detection limit down to 0.36 ng·ml-1. So, the proposed probe is well-suited and selective for detecting the ultratraced ProGRP.(4) A new type of fluorescence and phosphorescence liquid sensor arraywas fabricated for different types of lung cancer cell metabolism based on the spectral characteristic of quantum dots. The fluorescence and phosphorescence intensity of quantum dots were changed after the interaction between the QDs with the metabolites of five types of lung cancer cells and a normal cell, and the original fluorescence and phosphorescence response can be converted into standardized mode as a "finger print".The fluorescence and phosphorescence data from the sensor array were analyzed with pattern recognition methods of the principle component analysis(PCA). The results demonstrated the liquid sensing array of quantum dots can be used to identify the five different type of lung cell A549, H1299, H292, H446, H460 cells and the normal cell of MCR-5 with a simple, fast and high anti-interference ability.