Single CEA Molecule Electrochemical Detection And Electrochemical Analysis Of Organics Based On Chemically Modified Electrode

The main research work is described as follows:1. Single molecule electrochemical detection of CEA based on magnetic nanobead technology by a combination of enzyme-linked technologyA new electrochemical method for detection of single CEA molecule is developed based on counting single magnetic nanobead (MNB). In this method, CEA molecules are captured on a silanized substrate through sandwich immunoreactions.Then, MNBs are initially immobilized on silanized substrate at 1:1 molar ratio with target CEA. Subsequently, the MNBs are released from the silanized substrate via de-hybridization and the released MNBs are then labeled with alkaline phosphatase (AP). The resultant AP-MNBs with enzyme substrate disodium phenyl phosphate (DPP) are introduced through a capillary. AP on the AP-MNBs converts a huge number of DPP into its product phenol and phenol zones are produced around each moving AP-MNB. The phenol zones are continuously delivered to the capillary outlet and detected by a carbon fiber disk bundle electrode at 1.05 V. An elution curve with peaks is obtained. Each peak is corresponding to a phenol zone relative to single target CEA sequence. The peaks on the elution curve are counted for CEA quantification. The detection limit for CEA in this method is 5.0×10-17 mol/L.2. Simultaneous voltammetry determination of naphthol isomers by nano-gold/poly (3-methyl-thiophene) modified electrodeNanotechnology and electrochemical analysis technology are combined in this paper. Gold chloride acid is directly reduced to gold nanoparticles and modified glassy carbon electrode using electrochemical deposition method and then the electrode is put into 3-methylthiophene solution to polymerize. At last, we get a nano-gold/poly(3-methyl-thiophene) modified glassy carbon electrode (nano-Au/P3MT/GCE) with high sensitivity and selectivity. The study shows that detecting 1-naphthol and 2-naphthol with nano-Au/P3MT/GCE can effectively enhance the electrochemical response of naphthol isomers. And using the semi-differential technique, the oxidation peaks of the two kinds of material are completely separated, so we successfully achieve the simultaneous determination of naphthol isomers. This method is stable and sensitive. The recovery and precision are high for the determination of naphthol isomers in simulated water samples.1-naphthol and 2-naphthol detection limits are 1×10-7and 3×10-7 mol/L3. Determination of dopamine in the presence of ascorbic acid using nano-gold/ poly(Sulfosalicylic Acid) modified glassy carbon electrodeIn this paper, we first get a sulfosalicylic acid polymer modified glassy carbon electrode (PSA/GCE) through the electrochemical polymerization. Then we fabricate a nano-gold/poly(Sulfosalicylic Acid) modified electrode (PSA/nano-Au/GCE) using one step electrochemical deposition method with high sensitivity and selectivity of gold nanoparticles and PSA. The results show that PSA/nano-Au/GCE includes high sensitivity and selectivity of gold nanoparticles and PSA. This method can detect dopamine in the presence of ascorbic acid, the detection limit of DA is 9.5×10-8 mol/L.