| Microfluidics is the new technique developed in the past two decades that can precise control and manipulate fluids in micron size, typically in microliter, nanoliter or even picoliter volumes. Chemical and biological reactions which are traditionally carried out in laboratories now can be miniaturized on the microfluidic chip. It has advantages such as high throughput, high reaction efficiency, enhanced mobility as well as reduced sample and reagent consumption.Microfluidics has been utilized in many fields, particularly in the area of biochemical analysis. Many bio-analysis about nucleic acids, amine acid, proteins, cells and toxin by microfluidics technology have been reported.At the same time, Pollution of the environment has received unprecedented attention.The monitoring and detection of the pollution is the basic work to repair the environment. Effective detection technology can provide strong support for environmental pollution and prevention, and also provide evidences and effective assessment for public health and safety.There are many mature technologies to detect and monitor environmental pollutants. For the detection of atmospheric pollutants, methods such as Gas chromatography, the infrared absorption, electrochemical analysis are all qualified. And as for pollutants in the water, we can use chromatographic detection method, immunology, and biological detection method.All these technologies have good precision and accuracy, but most of them are expensive, and need either long analysis period or complex operation, not suitable for on-site detection. There is a great need to develop a portable, high-throughput and sensitive method for rapid detection of pollutant.Nowadays, the combination of microfluidic chips and the detection of pollutants appeal more and more attention.And in this paper, we successfully built the immunoreactions platform on microfludic chips, and utilized to develop the rapid detection technology for cotinine and glyphosate.In the first part, a microfluidic immunoassay is successfully developed for rapid analysis of cotinine saliva samples, which is a metabolite of nicotine and is widely used as a biomarker to evaluate the smoking status and exposure to tobacco smoke. The core microfluid ic chip is fabricated by polydimethylsibxane (PDMS) with standard soft lithography. The analyses can be completed within40minutes with12μl sample consumption.The linear detection range is1-250ng/ml and the minimum detectable concentration is lng/ml respectively. The correlation coefficient of the calibration curve established from standard samples is0.9989. The immunoassay was also validated by real saliva samples, and the results showed good reproducibility and accuracy. All the results were confirmed with traditional ELISA measurements. The result from microfluidic chip device and ELISA kits showed good correspondence, and the correlation coefficients are higher than0.99. Compared with traditional technique, this microfluidic immunoassay is more economic, rapid, simple and sensitive, perfect for on-site cotinine measurements as well as for the evaluation of the exposure to tobacco smoking. Moreover, this immunoassay has potential to be applied in the analysis of other biomarkers in human saliva samples.In the second part, a microfluidic immunoassay is successfully devebped for rapid analysis of glyphosate, The analyses can be completed within40minutes with10μl sample consumption or less. The linear detection range is0.075ppb to4ppb and the minimum detectable concentration is0.075ppb respectively. The immunoassay was also validated by real saliva samples, and the results showed good reproducibility and accuracy. This microfluidic immunoassay is prospective for on-site glyphosate measurements Moreover, this immunoassay has potential to be applied in the analysis of other pesticide pollutants. |
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