Fluorescence Detection Of Serval Vascular Endothelial Cell Injury Markers And Iodide

Some noble metal nanoparticles and nanocomposites exhibit characteristic absorption spectrum in visible region,which can be overlapped by the fluorescence emission spectra of usual energy donors.They have got tremendous attention in the chem/biosensing that is performed based on fluorescence resonance energy transfer?FRET?.Antibody-immobilized noble metal nanocomposites and core-shell noble metal nanoparticles were prepared in the present work and they were used in the quantitative detection of two markers of vascular endothelial cell injury and the highly sensitive determination of iodide ion.The main contents are listed as follows.1.A highly sensitive fluorescence method for the quantitative detection of TM was developed.TM antibody?Ab?and bovine serum albumin?BSA?were bound on gold nanoparticles to construct BSA-AuNPs-Ab nanocomposites and they were characterized by transmission electron microscope and UV–vis absorption spectroscopy.The fluorescence of acridine orange?AO?was quenched by the prepared gold nanocomposites based on fluorescence resonance energy transfer?FRET?.In the presence of TM,the fluorescence was turned on due to the effective separation of AO from the surface of gold nanocomposites.Under optimum conditions,the enhanced fluorescence intensity displayed a linear relationship with the logarithm of the TM concentration from 0.1 pg mL^-1 to 5 ng mL^-1with a low detection limit of 12 fg mL^-1.The release of soluble thrombomodulin?sTM?by the injured HUVEC-C cells in the presence of H₂O₂ was investigated using the proposed method.The released sTM content in the growth medium was found to be increased with the enhancement of contact time of the cells with H₂O₂.2.Graphene quantum dots?GQDs?and core/shell Ag@Au nanoparticles?Ag@Au NPs?were synthetized and they were characterized by transmission electron microscope.Von Willebrand factor antibody?vWF Ab?was bound on Ag@Au NPs to construct Ag@Au-Ab nanocomposites?Ag@Au-Ab NCs?.The fluorescence of GQDs could be effectively quenched by the prepared nanocomposites based on FRET.The immunoreaction between vWF and Ag@Au-Ab NCs resulted in the separation of GODs from the nanocomposite surface and a degree of fluorescence recovery of GQDs.The fluorescence intensity change was found to be proportional to the logarithm of the vWF concentration in the range of 0.1 pg mL^-1-10 ng mL^-1 with a detection limit of 30 fg mL^-1.The proposed method was also employed to investigate the release of vWF by the injured HUVEC-C cells that were induced by H₂O₂.The experimental results indicate that the cell injury was intensified and the vWF content in the growth medium was enhanced when the contact time of the cells with H₂O₂ was increased.3.A simple sensor based on colorimetric and fluorescence double signals was developed for the quantitative detection of iodide ion.FRET between the prepared GQDs and core/shell Cu@Au nanoparticles?Cu@Au NPs?caused the fluorescence quenching of the former.The reaction of I^-with Cu@Au NPs could destroy the structure of the latter and produce global gold nanoparticles with decreased size.The color of the Cu@Au NPs solution changed from purple to wine red with the increase of the I^-concentration.The addition of I^-into the GQDs-Cu@Au mixing solution resulted in the further quenching of GQDs fluorescence.A linear relationship existed between the declining extent of the fluorescence intensity and the concentration of I^-in the range of 0.05?M-5?M.The proposed method was successfully applied in the determination of I^-in water samples.