Application Of Microfluidic Paper-Based Chips In Environmental And Biological Analysis

Accompanied by development of science,analytical sensing technologies based on physics and chemistry have showed extremely application value.According the times,analytical science and sensing technology face the new challenges.It is an urgent to develop the more compact,efficient,rapid and real-time analytical sensing methods in all fields.The development of microfluidic paper-based device provides ideas for building a new type of low-cost,convenient and efficient analysis platform.The key for building an sensing method on a paper-based platform is combining with advanced materials such as nanomaterials,polymers,and biomaterials on paper-based materials,as the basic operations of the analytical process.In this dissertation,a series of low-cost,convenient,sensitive,and selective rapid analysis methods and paper-based devices are designed and manufactured from the perspective of operability of the entire process of synthesis and analysis on microfluidic paper-based platform,combining molecular imprinting technology and immunoassay technology.The fluorescence sensing,electrochemical sensing,and colorimetric sensing methods on the paper-based platform were constructed.In addition,the paper-based sensing mechanism based on advanced functional materials is studied.Moreover,the paper-based devices have been applied in the analysis of pollutants in actual environmental water samples,amino acids in human urine,and tumor markers in clinical serum samples.The works are abstract as following:1.Rotational paper-based microfluidic-chip device for fluorescence detection of phenolic pollutants based on a molecular-imprinting technique.We first present rotational paper-based microfluidic chips combined with a molecular-imprinting technique to detect phenolic pollutants.The proposed rotational paper-based microfluidic chips could implement qualitative and quantitative analysis of two different phenolic contaminants,4-nitrophenol and2,4,6-trinitrophenol,simultaneously.Qualitative and quantitative analysis could be implemented simultaneously through fluorescence-intensity changes depending on the structures of quantum dots combined with a molecular-imprinting technique.Under the optimal conditions,the proposed sensors showed high sensitivity and selectivity.Our final experimental results illustrated that the detection of 4-nitrophenol and 2,4,6-trinitrophenol in the paper-based device ranged from 0.5 to 20.0 mg/L,with detection limits of 0.097 and 0.071 mg/L,respectively.The recoveries from the lake-water and seawater samples were ranging from 92.6 to 106.6%.2.The cross-type paper-based device for analysis of microcystins-RR based on the indirect fluorescence response of molecular-imprinting technique strategy.Using virtual template imprinting technology and epitope imprinting technology,Zn Fe₂O₄ nanoparticles coated with molecularly imprinted polymers specifically adsorbing microcystin-RR were prepared and used as fluorescence quenching of Cd Te quantum dots.Quencher,fluorescence quenching obeys the fluorescence quenching mechanism caused by electron transfer between particles,and then constructs an indirect molecularly imprinted fluorescence sensing mechanism on a slidable type microfluidic paper chip device for use in the water environment rapid analysis of microcystin-RR.Scanning electron microscope,transmission electron microscope,X-ray diffractometer and other series of instruments and methods were used to characterize the preparation materials and paper-based sensing systems,further study to optimize the paper chip preparation process and analysis conditions,The analysis results confirmed the effectiveness of the chip method.A calibration linear curve was fitted based on the analysis results of standard samples and the Stem-Volmer equation.The device achieves selective and rapid detection of microcystins-RR within 20 min.Our final experimental results illustrated that the detection limits of microcystins-RR in the paper-based device is 0.43?g/L.The recoveries from the seawater samples were ranging from 90.1%to 105.3%.3.The gold nanocluster fluorescence sensing microfluidic paper-based device based on the coffee ring effect for detection of amino acid.A coffee ring-type fluorescent sensing paper-based device was constructed,which used the coffee-ring effect caused by different capillary forces and different evaporation speeds in the paper-based material of the solution,combining with the complex fluorescent probe formed by gold nanoclusters and copper ions.The smart phone was used to collect RGB image by the way of taking pictures,which realizes a sensitive and selective method of visualizing the fluorescent sensing paper-based device for convenient detection of histidine in urine.A linear calibration curve was fitted according to the analysis results of the standard samples.The detection limit was 0.021 m M.The method was successfully applied to the analysis of histidine in human urine samples,and the recovery range was 93.0-110.0%.4.Analysis of carcinoembryonic antigen by electrochemical sensing microfluidic paper-based device based on in situ synthetic biomolecular imprinting.We provided a novel strategy of antibody-free biomarker analysis by in-situ synthesized molecularly imprinted polymers on movable valve microfluidic paper-based electrochemical device for clinical detection of biomarkers.The newly movable valves on the device enable continuous and convenient delivery of fluid,which guarantee the performance for fabricating MIPs structure during long time electropolymerization.To further validate the applicability of this proposed method for clinical diagnostic testing,carcinoembryonic antigen was applied as prototyping model target for the clinical analysis.The device has a detection range of 1.0-500.0 ng/m L and a detection limit of 0.32 ng/m L for detection of carcinoembryonic antigen.It was successfully applied to the clinical analysis of carcinoembryonic antigen in cancer patients serum and relative standard deviation ranged from 2.7%to 6.5%.5.Colorimetric and immunosensing microfluidic paper-based device with integrated manual centrifugation for analysis of tumor markers.We present a microfluidic system that centrifuges whole blood and quantifies contained biomarkers in a fully integrated fashion and without the use of electric power.Such a device provides a blood-in/answer-out capability and is small enough to be carried by any individual in any environment.The successful integration a hand-powered centrifuge and immunoassay unit within a rotational paper-based device allows for diagnostic application by untrained users and in environments where access to electricity cannot be assumed.After experimental investigation,the detection limit of the paper-based device for detection of carcinoembryonic antigen is 0.36 ng/m L,and the detection limit for detection of alpha fetoprotein is 0.28 ng/m L.Finally,the quantitative results of the two tumor markers carcinoembryonic antigen and alpha fetoprotein in human blood samples have relative standard deviations between 4.03% and 5.21%.