Study Of Electrochemical(Bio) Sensor Based On Temperature Sensitive Polymer/carbon Nanomaterial

In the development of new electrochemical(bio)sensor,the sensitivity,selectivity,detection efficiency and cost of detecting target molecules are generally considered as the main factors to be applied in environmental,safety,agricultural or food applications,and healthcare(including clinical diagnosis and disease treatment).Electrochemical(bio)sensor are becoming an important part of modern life because of their application in biology,biomedical,biotechnology,clinical and medical diagnostics,environmental and health monitoring,as well as the food industry.With the increasing demand for ultra-sensitive bio-analysis,a series of its advantages have driven the continued development of electrochemical(bio)sensor platforms,such as low-cost,miniaturized,energy-efficient,easy-to-manufacture,online monitoring,simultaneous sensing capabilities and so on.Stimulating responsive polymer is a newly developed type of new functional polymer material that responds quickly to weak external stimuli and then produces a gradual change in layout,physical function and chemical function.The application of nanomaterials for electrochemical(bio)sensor can greatly improve their performance and application range,thus promote the advancement of biosensor.It is a new research hotspot to prepare the electrochemical sensing platform with environmental stimuli response by mixing stimulating responsive polymer and nanomaterial together and then modifying to the electrode,which realize the regulation of target molecule electrochemical signal and electrochemical intelligent detection.The main research of this thesis is the construction and performance regulation of temperature-responsive electrochemical(bio)sensor.The main contents are as follows:(1)Reductive.graphene oxide(rGO)-fullerene(C60)composite carbon nanomaterials were synthesized by electrochemical method,and thermosensitive polymer poly(2-methyl-2-acrylic acid-2-(2-methoxy).The temperature-sensitive composite was prepared by mixing ethoxy)ethyl ester(PMEO2MA)and modified on a glassy carbon electrode.When the temperature is lower than the minimum critical solution temperature(LCST),the polymer PMEO2MA chain is in a stretched state,and the interlayer distance of the rGO layer is increased,resulting in the layer C60 not being in contact with another layer of rGO,and the conductivity is poor and cannot be detected.Ractopamine;when the temperature is higher than LCST,the polymer PMEO2MA chain shrinks,which makes C60 contact with another layer of rGO,which improves the stability of the composite modified membrane and increases the electron transfer rate,so the electrochemical response of ractopamine is obvious.Therefore,the sensor achieves temperature "on-off" regulation of the electrochemical behavior of ractopamine.(2)The Au@rGO-CNT composites were synthesized by hydrothermal method and mixed with the temperature sensitive polymer PMEO2MA to achieve the temperature "on-off" regulation of dopamine electrochemical behavior on the glassy carbon electrode.When the temperature is lower than LCST,the polymer PMEO2MA chain is in a stretched state,dopamine can not reach the electrode surface through the polymer film,dopamine electrochemical behavior can not be carried out;when the temperature is higher than LCST,the polymer PMEO2MA chain shrinks,makes MWCNTs contact with the other layer of Au@rGO,the electron transport rate of the modified film increases,and the electrochemical behavior of dopamine is turned on.(3)Firstly,the temperature-sensitive polymer PS-PDEA-PS was synthesized,and then combined with carbon nanomaterials MWCNTs by non-covalent bonding to form a temperature sensitive electrochemical sensor film.A temperature "on-off" sensor for the detection of acetaminophen(AP)was constructed by using the membrane-modified glassy carbon electrode.When PS-PDEA-PS swells below its LCST(30℃),the interface resistance of PS-PDEA-PS/MWCNTs is higher,the electron transfer rate is slower,and the electrochemical response of AP on the modified electrode is turned off;while PS-PDEA-PS shrinks above its LCST,the interface conductivity is higher,the electrochemical response is turned on,and the solution temperature is repeatedly changed,as well as the modified electrode exhibits a reversible effect.(4)The C60-MWCNTs composite carbon material was synthesized by low temperature ultrasonication and combined with the temperature sensitive polymer PS-PDEA-PS by non-covalent bonding to form a temperature sensitive electrochemical sensor membrane.The temperature "on-off" detection of catechol was achieved with the modified glassy carbon electrode.When the temperature is above LCST of PS-PDEA-PS,the electrochemical behavior of catechol can be detected,which is in an "on"state.When the temperature is lower than the LCST,the composite modified film is in the "off" state,and the electrochemical behavior of catechol can not be detected.(5)Glucose oxidase(GOD)is encapsulated in a composite of poly(N-vinylcaprolactam)(PVCL)and graphene oxide(GO)to prepare a sensing film with temperature-inducing effect and used to modify in the glassy carbon electrode,conducting a biosensor for temperature-controlled electrocatalytic glucose.When the temperature is lower than the LCST,the polymer PVCL chain is in an extended state,the GOD cannot be in contact with the electrode surface,direct electron transfer is prohibited,and the glucose catalytic reaction cannot be performed.When the temperature is higher than LCST,the PVCL chain of the polymer is a contracted state,and GOD can reach the surface of the electrode to realize a direct electron transfer process,and the glucose catalytic reaction can be smoothly realized.