The Study Of Electrochemical Luminescence Sensors And Precious Metal Clusters Fluorescent Sensors

Noble metal nanoclusters, as a novel fluorescent nanomaterials, due to its excellent optical properties, unusual physical and chemical properties as well as good biocompatibility, have been widely used in analysis sensing. However, there are still some deficiencies and shortcomings related to the synthesis and applications of the fluorescent nanoclusters:?1? complicated and time-consuming preparation process; ?2? traditional fluorescence analytical techniques exsists some flaws, such as the obtained signal output was easily influenced by the probe concentration, photo-bleaching and light source stability and so forth, resulting in reduced detection sensitivity.Electrochemiluminescence ?ECL? was developed based on the combination of electrochemisty with chemiluminescence. This analysis technology has some advantages, such as simple and quick, high sensitivity, wide detection range, good controllability, easy to implement real-time and integrated, it can be carried out in situ detection. With these advantages, it has raised greatly interesting of researchers. In the past decades, many luminescence systems, such as Ru?bpy?3²⁺-tripropylamine ?TPA?, luminol-H₂O₂ and QDs-S₂O₈^2-, have been widely investigated and applied in chemical analysis. Nevertheless, the ECL of dissolved oxygen was always ignored as background emission in above systems, or the ECL signal of dissolved oxygen was weak. Hence, the luminescent of dissolved oxygen has not get the attention of researchers, but did not further discuss its application.In this thesis, we used a simple green "one-pot" synthesis method for producing different protective agents synthesized gold nanoclusters ?Au NCs? firstly. Secondly, we introduced titanium dioxide nanoparticles ?TiO₂ NPs? as the catalyst to enhance the ECL intensity of the 2-?dibutylamino?ethanol and dissolved oxygen ?DBAE+O₂? system. Based on the above work, we built a range of different luminescence sensors to realize high sensitivity and selectivity detection of metal ions and biomolecules. This thesis includes the following three parts:1. Water-soluble and dual-emitting bovine serum albumin-templated bimetallic platinum-gold fluorescent nanoclusters ?BSA-Pt-Au NCs? have been synthesized by a one-pot synthesis strategy. The BSA-Pt-Au NCs show unique and well-resolved dual-emission bands at 405 nm and 640 nm at the excitation of 340 nm, which is corresponding to the emission of the BSA-Au/Pt complex and Au NCs, respectively. And with the addition of Hg²⁺ions, the emission intensity of BSA-Pt-Au NCs decreases dramatically, which is due to the specific and strong d10-d10 interactions between Hg²⁺ and Au+. Meanwhile, cysteine ?Cys? could effectively block Hg²⁺ ions to quench the fluorescence of BSA-Pt-Au NCs, which is based on the strong interaction between Hg²⁺ and the thiol functional group. Therefore, based on the ratio of two emission intensities ?F405/F640?, a ratio of fluorescence sensor have been successfully built to detect Hg²⁺ and Cys with ultra-sensitivity and selectivity.2. In this paper, through the design of the synthetic steps and a large number of experimental conditions optimization, we successfully used the one-pot method to synthesis of the high fluorescence Cys-Au NCs, and the clusters own the emission wavelength of 525 nm at the excitation of 390 nm. Based on the fluorescence resonance energy transfer between Cys-Au NCs and Au NPs, the fluorescence of Cys-Au NCs was significantly quenched when the Au NPs added into the Cys-Au NCs solution. However, due to the stronger electrostatic adsorption of protamine on the surface of Au NPs, resulting in the recovery of the Cys-Au NCs fluorescence upon addition of protamine. But heparin is able to bind with protamine specifically, the interaction of heparin with protamine makes the Au NPs deaggregate, which lead to the fluorescence quench again. Based on the above principles, we built a heparin and protamine biosensor.3. The anodic ECL of the dissolved oxygen with DBAE on platinum ?Pt? electrode has been reported by the previous research work. On the basis of this study, we found that the ECL signal can be greatly amplified at TiO₂ NPs modified Pt electrode, which is due to the catalytic effect of TiO₂ NPs to electrochemical oxidation of DBAE. And the enhanced anodic ECL intensity can be quenched by DA sensitively. Based on the above phenomenon, we successfully constructed a simple, high selectivity and high sensitivity biosensors to detect DA.