| There is an important relationship between the water environment quality and the people’s healthy. With the rapid development of industry and agriculture and people living standard unceasing enhancement, the residual small molecule pollution such as POPs, EDC is becoming more and more serious in water environment. Conventional detection methods such as gas chromatography, spectrometry, chemiluminescence analysis method could not meet the real-time online detection due to lower precision, complex operation, uneconomical, the research of rapid detection technology has a significant role in preventing and controlling the trace amounts of organic contaminants in aquatic environment. The evanescent wave all-fiber-optical biosensor(EWA) can achieve fast, accurate quantitative detection of pollutants in the water environment based on the principal of the total internal reflection and fluorescence immunoassay, which employed a single-multi mode fiber optic coupler and the combined cone type structure of optical fiber immuno-probe for light excitation and collection of fluorescence generated from the fiber optic probe.In the research, surface modification and small molecular target organic pollutant immobilization method was established. High-loaded, stable and reproductive melamine immune-probe and sulfamethazine immuno-probe were achieved. A sensitive, simple and rapid detection of trace amounts of melamine and sulfadimidine in aquatic environment was achieved in the reusable, portable EWA system based on the indirect competitive reaction mode. The results showed that:(1) The research on the preparation of melamine fiber immunoassay and sulfamethazine immunoassay respectively has good specificity of the antibody of melamine antibody and sulfadimidine antibody. Nonspecific adsorption of other antibodies is very weak, and the stability of the fiber probe is very high.(2) The standard curve of melamine and sulfamethazine detection by EWA were consistent with the mathematical function of the Logistic model, both the relative standard deviations are higher than 0.99. The typical calibration curves of the EWA obtained for melamine had a detection limit of 5.14 μg/L with the detectable working range from 12.62 to 284.18 μg/L, the IC50 value is 59.89 μg/L. The detection limit of sulfamethazine is 0.05 μg/L with the detectable working range from 0.17 μg/L to10.73 μg/L, the IC50 value is 1.35 μg/L. The recoveries in all sorts of sample products ranged from 86 % to 116% with relative standard deviation values of less than 4%, confirming the application potential in the measurement of Mel and SM2 in reality. The immunoassay performance of the EWA was also validated with respect to conventional LC-MS/MS and the correlation between methods was in good agreement. Cross-reactivity against the organic compounds structurally similar to MA / SM2 was negligible.(3) A reusable immune-surface of fiber probe was established to allow the performance of more than 300 assay cycles with relative standard deviation values of less than 1.2%. Each assay cycle was less than 15 min. Reusable immuno-fiber probe can greatly reduce the detection cost.In this study, the research of ultrasensitive method for the detection of small molecules in aquatic environment pollution can meet the requirements of the actual detection of melamine and sulfamethazine residues. The EWA with good accuracy and stability can realize the real-time, accurate detection of environmental pollutants. The results of this study is good for the EWA into wise use in the field of water environmental monitoring. |
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