The Study Of High Sensitive And Quantitative Immuochromatographic Assasys Based On Quantum Dots And Noble Metal Nanoparticles

Immunochromatography assay(ICA) is an analytical method which combines immunoassay with chromatography. Traditional ICA is mainly based on colloidal gold which is usually used for qualitative and semi-quantitative analysis with the features of simple operation, short testing time and low coat. Colloidal gold based ICA is seldom used for quantitative analysis due to its low sensitivity. Recently with the emerging of different new materials and the application of these materials in ICA, a big progress in the study of quantitative ICA has been made. Among them, fluorescent quantum dots(QDs) and noble metal nanoparticles with the high enhancement effect on Raman scattering provide the basic materials for the establishment of sensitive and quantitative ICA.In this study, QDs were prepared in oil phase and the homemade oil phase QDs were successfully transferred into aqueous phase by polymer coating method. The prepared quantum dots nanobeads displayed high quantum yield and high fluorescence efficiency. Based on these quantum dots nanobeads, the fluorescence immune-probe was prepared and the fluorescence immunochromatography assay(FICA) was developed. In addition, based on the prepared Au@Ag core-shell nanoparticles, the SERS immune-probe was prepared and the SERS immunochromatography assay(SERS-ICA) was establish. These two kinds of sensitive and quantitative ICAs have been applied for the determination of two kinds of β-agonists(bromobuterol and salbutamol) in samples.The thesis includes four parts:Firstly, the research background and significance of the thesis was introduced. The concept, characteristics, development status and limitations of ICA were described in detail. The development of nanomaterials especially quantum dots and their application in ICA were discussed. In addition, SERS-ICA was described.Secondly, compared to the quantum dots in aqueous phase, the oil phase quantum dots are superior in both stability and fluorescence intensity. So oil phase core-shell quantum dots were successfully prepared by organic solvent thermal method, and the effect of reaction temperature and time and other factors on the experimental results were explored. A series of characterization of the QDs was made.Thirdly, we successfully prepared polymer coated QDs by polymer microemulsion. The fluorescence stability, water dispersion, particle size and other properties of the nanobeads were characterized. By EDC activation method, the polymer coated QDs were linked to the polyclonal antibody against bromobuterol to form the immunofluorescence probe.Then the probe was used in FICA for the detection of bromobuterol. This detection process is completed in 20 minutes. The IC50 and limit of detection(LOD) of the proposed FICA for bromobuterol were 0.014 ngm L-1 and 0.53 pgm L-1, respectively, showing high sensitivity. Several otherβ-agonists were used for cross-reactivity(CR) experiment. The CR of the assay with clenbuterol is 28.6%. The recovery of bromobuterol in urine samples was 97.7~102.7% with the RSD of 1.9~3.3%. It is demonstrated that the proposed FICA is able to quantitatively and ultrasensitive detection of brombuterol in urine sample.Fourthly, Au@Ag core-shell nanoparticles were synthesized, and the immune probe was prepared by coupling the Au@Ag nanoparticles with mercaptopropionic acid(MBA) as Raman markers and then linked to the salbutamol antibody. The probe was applied in ICA for specific detection of salbutamol. The IC50 and LOD of the SERS-ICA for salbutamol were 0.028 ngm L-1 and 2.8 pgm L-1, respectively. It is proven that this method can be used for sensitive detection of salbutamol.