Enhanced Electrochemiluminescence Of Semiconductor Nanomaterials For Biosensing

As one kind of analytical method,electrochemiluminescence(ECL)is combining the electrochemical technique and chemical luminescence together.Electrochemiluminescence has been widely employed in a lot of research areas owing to its small background,high sens:itivity,and good selectivity and so on.Semiconductor nanocrystals have been used in biological markers and biological sensing widely due to their unique properties and good bio compatibility.The titanium dioxide nano tube arrays(TiNTs)are prepeared by anodic oxidation.Owing to their large specific surface area,highly ordered,vertical growth of tubular structure,good biocompatibility,TiNTs can be applied as electrode in biosening.The CdO-CdSe semiconductor nanocrystals prepeared by a simple ion exchange technique from CdO exhibit high electrochemiluminescence signa.In the first chapter,we first describe the mechanism,characteristic and application of the electrochemiuluminescence.Then,a brief introduction of the application of the semiconductor nanocrystals,the titanium dioxide nanotubes and quantum dots in the ECL is provided.In the end,the main ideas and the research contents of this thesis are listed.In the second chapter,a highly sensitive electrochemiluminescence sensor is developed based on carbon layer embedded TiNTs(C/TiNTs).A highly enhanced ECL signal is detected on the C/TiNTs based on the reaction between H2O2 and luminol,by which we realized the sensitive detection of H2O2.The detection of linear range is 2.0×10-6 to 5.0×10-4 mol/L with the detection limit 4.8×10-7 mol/L.Herein,a sensitive ECL biosensor can be constructed based on the reaction between luminol and H2O2 which is generated by the reaction between the enzymes and trace amounts substrate.In this work,the choline oxidase is fixed in nanotube wall by electrostatic attraction,and the choline in the environmental solution is catalysised by choline oxidase to form HO02.The detection of linear range is 5.0×10-8 to 2.0×10-4mol/L with detection limit 2.0×10-8 mol/L(S/N=3).In the third chapter,an ultra-sensitive ECL immunosensor is developed based on the CdO-CdSe semiconductor nanocrystals.The CdO-CdSe nanocrystals is prepared by anion exchange reaction,and the CdO-CdSe based electrode exhibits strong ECL property.Combining the avidin-biotin enzyme immunoassay with the biological catalysis precipitation technology,a signal emplified ECL immunosensor is constructed.In this work,due to the highly enhanced steric block induced by the precititation,the coreagent cannot reach to the surface of CdO-CdSe,which leads to the decrease and quenching of ECL signals.Thus,the high sensitivie detection of the target is realized.The detection of linear range is 1.0×10-15 to 1.0×10-9 g/mL,while correlation coefficient R is 0.9959 and the detection limit is 2.0×10-16 g/mL(S/N=3).