Study Of The Binding Characteristics Of HSA With Eosin B, Homemade Quantum Dot And The Detection Of Gallic Acid Using Quantum Dots As PH-sensitive Fluorescent Probe

Human Serum Albumin (HSA) is the important carrier protein in human body, which can bind different categories of endogenous and exogenous small molecules, and play a role in storage and transit. Investigating the binding mechanism between small molecules and HSA is significative in diagnostics, pharmaceutical and toxicology. Because semiconductor nanocrystals (also known as quantum dots) have many unique properties (especially the optical properties), they are favored by more and more researchers. In fluorescence probe, biological biomarkers and cell image, quantum dots have shown great potential applications. Based on the abovementioned research background, we have used molecular docking approach and multi-spectroscopic technology to study the binding characteristics of HSA with Eosin B and homemade CdTe@GSH quantum dot. Furthermore, we used homemade CdTe@TGA quantum dots as pH-sensitive fluorescent probe for detection of Gallic acid.This thesis is divided into four chapters:Chapter1:The structures, functions and properties of QDs and HSA were introduced. Various spectroscopic methods were reviewed, which are often used to study the binding characteristics between small molecules and HSA. Meanwhile, the methods used to detect trace materials by QDs and the latest applications were introduced.Chapter2:Under simulated physiologic conditions, the interaction of Eosin B with HSA was investigated by the combination of fluorescence, UV, FT-IR, CD spectroscopic and molecular binding technologies. Through molecular docking method, the binding site and binding mode were discussed. Fluorescence quenching data revealed the binding constants and the number of binding sites. The thermodynamic parameters and binding mechanism were also discussed. The results of synchronous fluorescence, UV, FT-IR and CD spectra indicated that secondary structure of HSA was changed in the presence of Eosin B. In addition, the binding distance was estimated according to the Forster non-radiative resonance energy transfer theory.Chapter3:CdTe@GSH QDs were synthesized in aqueous solution. The obtained QDs were characterized by UV-visible absorption spectrum and fluorescence spectrum, which indicates that as-prepared QDs are nearly monodisperse and homogeneous. The interaction between the as-prepared QDs and HSA was studied by fluorescence technique. The results were discussed on the binding parameters, the quenching mechanism, the nature of forces involved in the interaction, and the effect of QDs on the conformation of HSA.Chapter4:CdTe@TGA QDs were synthesized in aqueous solution. The relationship between its fluorescence intensity and pH was investigated. The experimental results showed that in the pH range4.0-6.5, the QDs was pH-sensitive. And a new method was developed to detect Gallic acid by employing CdTe@TGA QDs as pH-sensitive fluorescence probe. Under the optimal conditions, the linear range of this method was4.00-32.00μg/mL. The detection limit was0.44μg/mL and the correlation coefficient was0.9967. The method was applied to detect Gallic acid in synthetic samples and the obtained results were satisfactory.