Spectra Study On The Interaction Of Thiamin And Thiamin Capped CdSe Quantum Dots With Serum Protein

Quantum Dots (QDs), a semiconductor nanocrystal, possess the unique optical properties including photostability, brightness, narrow but tunable emission spectra and a broad spectral excitation cross section compared with organic fluorophores as fluorescently-labeled primer. Currently, QDs receive tremendous applications in some realms acting as a bioluminescence probe,such as immunity biology, biomedical science,bio-chemical analytical image and the clinical inspection learns,therefore,it arouses people's wide concern. However,The practical application of QDs always exists many difficulties because QDs has some problems,such as poor water-soluble ability,weak biological compatibility,low cell membrane penetration ability and toxicity for organisms. So we must operate the surface modification of QDs in order to improve the QDs water-soluble, specificity and biological affinity.This paper adopts thiamin(also called vitamin B₁, abbreviation for VB₁)which is essential in human body as modifier to synthesize CdSe QDs, and synthesized QDs was characterized by using transmission electron microscopy and infrared spectra. The mixture of VB₁ capped CdSe QDs synthesized in aqueous and Bovine Serum Albumin(BSA)was employed as the model to study the interaction of QDs with proteins. Moreover, this thesis investigates the interaction between BSA and VB₁ by studying combination constant, rate constant and reaction equilibrium constant. Study found that the interaction mechanism of these two systems between some similarities and differences, this study has certain practical significance not only for investigating the interaction mechanism between QDs and proteins, but also for proteins and application in biological marker.Chapter one summarizes characteristics and application of QDs. introduces all kinds of metheds for studying the interaction of nanomaterials with proteins,specifically,principle and application of fluorescence technology.In chapter two,the inteaction between VB₁ and CdSe QDs and application for the determination of VB₁ were studied,meanwhile, reaction of the Cys capped CdSe QDs with VB₁ results in an quenched fluorescence(FL). Under optimal conditions,the FL intensity is linearly proportional to the concentration of VB₁. The liner range is 1.7²7μg/mL for VB₁,and the detection limit is 0.33μg/mL. Base on this,a new method is developed for the determination of VB₁, and applied to the derermination of the real samples with satisfactory result.In chapter three, synthesis and characterization of VB₁ capped CdSe QDs which is specially functional material for human body was investigated,this is used to achieve the surface modification of QDs by medicine and obtain special QDs. Experimental results found that VB₁ capped QDs not only enhance biocompatibility but also make it stable greatly in aqueous solution.In chapter four, The interaction mechanism of bovine serum albumin (BSA) with VB₁ capped CdSe QDs was studied using fluorescence quenching spectrum and Synchronous fluorescence spectrum in this chapter. The experimental results demonstrate that the quenching mechanism of BSA by VB₁ capped CdSe QDs is static quenching, which was analysised by fluorescence spectroscopy and UV absorption spectroscopy. From thermodynamic coordination it can be confirmed that the binding force between VB₁ capped CdSe QDs and BSA is mainly hydrogen bond and VDW(Van der Waals' force). The effect of VB₁ capped CdSe QDs on the conformation of BSA was analyzed by synchronous fluorescence spectrometry.In chapter five,The interaction mechanism of bovine serum albumin (BSA) with VB₁ was studied using fluorescence quenching spectrum and Synchronous fluorescence spectrum in this chapter. The experimental results demonstrate that the quenching mechanism of BSA by VB₁ is dynamic quenching, which was analysised by fluorescence spectroscopy and UV-vis. From thermodynamic coordination it can be confirmed that the binding force between VB₁ and BSA is mainly hydrogen bond and VDW(Van der Waals' force). The effect of VB₁ on the conformation of BSA was analyzed by synchronous fluorescence spectrometry.