Electrochemistry Of Quantum Dots, Electrochemiluminescence Resonance Energy Transfer And Electrochemiluminescence Method Using Ru(bpy)₃²⁺-Coated Magnetic

In chapter one of this thesis,The electrochemistry of mercaptopropionic acid capped CdTe quantum dots(QDs) was studied by differential pulse voltammetry, three processes were obtained at 0.36(A1),0.68(A2) and 0.84 V(A3),respectively. A1 process could be selectively suppressed by magnesium ion,an electrochemical sensor for magnesium ion was developed with a linear response from 4.00×10^-5 mol/L～2.00×10^-2 mol/L and good reproducibility.This electrochemical sensing application of QDs may provide a new strategy for QDs-based detection.In chapter two,we reporte a novel resonance energy transfer(RET) technique, electrochemiluminescence resonance energy transfer(ECRET).In ECRET,the emitters of luminol/H₂O₂ system are generated at an electrode through electrochemical reaction and act as the electrochemiluminescent donors to emit light with a maximum emission of 425 nm.The red fluorescent luminescent semiconductor nanocrystals(quantum dots,QDs),having a maximum emission at 655 nm,are chosen as the acceptors.When a potential was applied to the electrode,the electrochemical donors transferred energy to the QD acceptors,producing efficient ECRET.The ECRET technique could be applied for the investigation of biomolecular interactions of proteins and nucleic acids,immunoassay and DNA assay.In chapter three,We develop an ultrasensitive electrochemiluminescence(ECL) method for the determination of biomolecules.This method uses magnetic submicrobeads(SMBs) as the carrier of a large number of luminophore molecules and carbon nanotubes(CNTs) as accessorial electrode material to amplify the signal.In this method,ECL of the luminophore molecules on the surface of the SMBs contacting both the electrode and the CNTs is detected.Using the protocol,an ultrasensitive DNA determination method is provided.First,one streptavidin-coated SMB(SA-SMB) is conjugated to one hybrid of a single target DNA sequence.Next,a huge number of Ru(bpy)₃²⁺species are bound to the SA-SMB.The SA-SMBs with Ru(bpy)₃²⁺ species are wrapped with CNTs and then immobilized on an Au electrode by means of a magnet.In the presence of tri-n-propylamine,a curve of ECL intensity versus potential with a maximum ECL intensity(I_m,ECL) at 1.35 V is obtained.I_m,ECL can be used to quantify DNA.Since one target DNA sequence corresponds to one SA-SMBs with a large number of Ru(bpy)₃²⁺,as well as the Ru(bpy)₃²⁺-loaded SA-SMBs are wrapped with CNTs and immobilized on the Au electrode,not only the Ru(bpy)₃²⁺ molecules contacting the Au electrode but also the Ru(bpy)₃²⁺ molecules contacting the CNTs are electrochemically oxidized.Thus,the second ECL wave of Ru(bpy)₃²⁺ is increased greatly,leading to increased sensitivity.Using this method,a linear relationship between I_m,ECL and the DNA concentration is obtained in a range of 3×10^-16 to 1×10^-13 mol/L.