Quantitative Analysis Of Complex Systems By The Usage Of Molecular Probe Techniques In Combination With Advanced Quantitative Models

Both surface-enhanced Raman spectroscopy(SERS)and fluorescence spectroscopy have many advantages,such as fast detection,high sensitivity,simple operation,and applicability for in-situ detection,and therefore have great applicative potential in many fields.However,due to the uncontrollable variations in the physical properties of SERS enhancing substrates which have significant influence on the SERS intensities of the analytes of interest,SERS is still a qualitative or semi-quantitative technique.When fluorescence spectroscopy is applied to turbid samples or samples with both background interference and matrix effects,the relationship between the concentration of the analytes of interest and the corresponding fluorescence measurements does not follow the commonly assumed linear model anymore,which will greatly affect the accuracy and precision of quantative results.In this thesis,advanced data analysis methods including the spectral shape deformation quantitative theory(SSD)and the calibration model optimization strategy based on standard addition have been tentatively employed to solve the above mentioned problems encountered during quantitative analysis of complex systems using SERS or fluorescence techniques.In the second chapter of this thesis,a kind of core-shell nanoparticles,(i.e.,Au-core@4-mercaptobenzoic acid@Ag-shell)was systhesized and used as SERS enhancing substrate for quantitative SERS assays to avoid the problem of possible competitive absorption between the analytes of interst and the internal standard on the surfaces of the enhancing substrate.The core-shell nanoparticles in combination with SSD had been applied to the quantification of 6-thioguanine in samples of urine and red blood cells.The proposed strategy could effectively correct variations in SERS intensities induced by changes in physical properties of the enhanced substrate,and hence achieved quite accurate quantitative results.In the third chapter of this thesis,an intensity-based fluorescence probe for the detection of MCF-7 human breast cancer cells was designed based on the specific binding ability of a modified aptamer for MCF-7 human breast cancer cells.Fast and accurate quantification of MCF-7 human breast cancer cells in buffer solutions was achieved by the combination of the fluorescence probe with the calibration model optimization strategy based on standard addition.In the fourth chapter of this thesis,a fluorescence sensing method for the detection of Dam methyltransferase was proposed by combining the exonuclease III-assisted signal amplification technique and probe-based target fishing strategy.The proposed sensing method was integrated with the calibration model optimization strategy based on standard addition,and successfully realized accurate quantitative analysis of Dam methyltransferase in serum samples.