Electrochemical Immunosensors For Nonylphenol Based On Nanomaterials And Tethered Bilayer Lipid Membranes

The environmental security problem of environmental estrogens has become one of focus concerns around the world,because of its ecological toxicity,biological accumulation and degradation resistance.Nonylphenol(NP)has been recognized as a kind of typitical alkylphenolic environmental estrogen.It is widely used in plastics and detergents industry,and is widely distributed in aquatic environment,food packaging materials,toys and personal care products.However,NP can be stable in the environment and produce long-term harm to human via biological enrichment or amplification,due to its high hydrophobicity and lipophicity.It is particularly important to develop an analytical method that can rapidly and accurately detect nonylphenol.Here,we have fabricated several electrochemical immunosensors with high sensitivity,good stability and compatibility by combining the unique properties of nanomaterials and bilayer lipid membranes.The prepared sensors were applied for analysis of nonylphenol in complex samples.The thesis contains the following contents:In chapter one,an overview of the distribution and harmness of nonylphenol was provided,focusing on the sample preparation and detection methods for nonylphenol,as well as the application of nanomaterials and biomimic membranes in the electrochemical immunosensors.Finally,the research content and significance of this thesis were proposed.In chapter two,a label-free electrochemical immunosensor was developed for specific analysis of nonylphenol,based on the good conductivity and electrocatalytic property of multi-walled carbon nanobubes(MWCNTs)and gold nanoparticles,as well as the specific recognition of nonylphenol antibody to nonylphenol.Differential pulse voltammetry(DPV)was applied for the fast detection of nonylphenol,based on the change of oxidation peak current of Fe(CN)64-/3-as an electrochemical mediator.The concentration linear range of nonylphenol were 1～10 ng/mL and 10～250 ng/mL,and the detection limit was 0.65 ng/mL.The recoveries from the polluted water samples ranged from 84.5%to 109.6%.This method provides a fast and specific detection tool for the in-situ monotoring of aquatic environment.In chapter three,a new type of competitive electrochemical immunosensor was designed,based on the tethered bilayer lipid membranes(tBLMs)modified gold electrode.Owing to the good biological compatibility,tBLMs provides a natural environment for the immobilization of immunogenic molecules.And the electroconductivity of tBLMs could be increased significantly by the deposition of gold nanoparticles.Horseradish peroxidase-functionalized nonylphenol monoclonal anatibody(HRP-anti-NP)was incorporated on the membrane interface via a competitive format.Indirect detection of nonylphenol can be realized by measuring the catalytic current of horseradish peroxidase(HRP)to the hydrogen peroxide.Under the optimized conditions,nonylphenol can be detected in a concentration linear range of 0.1～500 ng/mL,with the detection limit of 0.054 ng/mL.The proposed sensor was proved to be sensitive and effective enough for nonylphenol analysis in the water and sediment samples.In chapter four,biomimic membrane-based electrochemical immunosensor was designed and fabricated for sensitive detection of NP.A dual signal amplification strategy was proposed by using the gold-platinum nanoparticles-doped tethered bilayer lipid membranes as the sensor matrix,and a gold nanoparticles-labeled horseradish peroxidase-linked nonylphenol antibody(Au-HRP-anti-NP)as labels.Hydroquinone was used as the electrochemical mediator for the synergetic catalysis of HRP and gold-platinum nanoparticles to the hydrogen peroxide.The concentration linear range for nonylphenol detection reached five orders of magnitude,and the detection limit was 0.030 ng/mL.The recoveries from the soil and leather samples were in the range of 83.4%and 103.0%.The results indicated that the electrochemical response characteristic of the immunosensor can be greatly improved by introducing the biological compatibility of biomimetic membranes,the signal amplification of nanomaterials and the enzymatic catalysis.These immunosensors can be applied for the research and monitoring of nonylphenol pollution in environment.