Study On Electrochemical Sensor And Homogeneous Electrogenerated Chemiluminescence Irnmunoassay

This thesis includes two parts, review and research reports. The first part involves the general situation, principle and types of electrogenerated chemiluminescence (ECL). Recent applications of ECL in bioanalysis are reviewed, which includes applications of ECL in biosensor, immuno sensor, DNA probe, surface analysis and enzyme analysis. The research reports are composed of three theses: (1) An amperometric glucose biosensor incorporated a permeable pre-oxidation layer is proposed to eliminate interference from readily oxidizable interfering components, (2) The enhancement effect of ethanol on ECL of ferrocene-luminol-hydrogen peroxide is studied, (3) Luminol-digoxin is synthesized and purified and its ECL character is studied.1 SummaryPrinciple and recent application of electrogenerated chemiluminescenceECL is intensively researched in resent years because it has high sensibility, good selectivity and wide linear range. It is easy to be controlled and needs only inexpensive instruments.There are typically four types of ECL systems: (1) ECL of polyaromatic hydrocarbons, (2) ECL of luminol, (3) ECL of metal complexes and clusters, (4) Cathodic ECL. ECL is widely used in biosensor, immune sensor, DNA probe, surface analysis and enzyme analysis. How to linkup ECL with microscope techniques such as STM, develop new ECL reagents, overcome electrode pollution are main directions of ECL research.2 Research reports(1) An amperometric glucose biosensor incorporating a permeable pre-oxidation layerAmperometric detection of hydrogen peroxide (i.e. first generation biosensor) and even of some electron transfer mediators (i.e. second generation biosensor) requires arelatively high oxidation potential (i.e., >+0.6 V vs. SCE) and, thus may suffer severe interference from readily oxidizable species such as ascorbic acid and uric acid. A glucose amperometric biosensor incorporating a mediator/glucose oxidase(GOx)/PbO2 layer is designed, aiming at exploiting analytical application of a pre-oxidation layer to a second generation biosensor and improving overall selectivity of the amperometric biosensor at high working potential for potential use of analyzing glucose in decentralized laboratory. When ascorbic acid is lower than 2.6 mmol I/1 and uric acid is lower than 1.6 mmol L~', the response of the sensor is not decreased. The result shows that PbOi layer adjacent to GOx layer serves as a permeable pre-oxidization layer that removes ascorbic acid with its strong oxidizing ability without effect on activity of GOx and concentration of glucose.(2) Enhancement effect of ethanol on electrogenerated chemiluminescence of ferrocene-luminol-hydrogen peroxideEthanol is found greatly enhance the ECL of ferrocene-luminol-hydrogen peroxide on platinum electrode and greatly decrease the ECL of luminol-hydrogen peroxide. ECL character of ferrocene-luminol-hydrogen peroxide is studied in present of ethanol. Detection conditions of luminol and ferrocene are optimized. The overall results allowed us to conclude that ethanol can enhance the catalysis-based ECL reaction by increasing the oxidation effect of ferrocene on electrode. This catalysis-based ECL reaction is also investigated in six other organic solvent-water mixtures, in which methanol and glycerol showed similar catalytic activity to the ECL reaction. A new ECL detection method of luminol and ferrocene is established.(3) Synthesis, purification and the ECL character of luminol-digoxinA new type of homogeneous ECL immunoassay is proposed by labeling luminol to hapten (e.g. digoxin). The method of synthesizing and purifying of luminol-digoxin is established. Two modes of homogeneous ECL immune are devised which based on space effect and stereo effect, respectively. ECL character and immunoassay character of luminol-digoxin is studied. The result shows that it is feasible to introduce luminol-digoxin into homogeneous ECL immunoassay.