Studies On Temperature-responsive Electrochemical Sensor Based On Poly(N-vinylcaprolactam)

With the development of material science and electrochemistry sensors,the conventional electrochemical sensors based on traditional materials cannot meet the requirements of the researchers.The scientists tried to combine materials with different properties to form a new composite material in order to modify the electrode,expecting novel electrochemical characteristics of the electrode via the synergistic effect among components of the composite.The thermo-sensitive polymers and the carbon nanomaterials exhibit the property of molecular structure transformation under temperature control,electronic conductivity and electrocatalytic,respectively.A new kind of nano-composite,obtained by mixing these two together,is used to modify electrode directly or immobilize redox protein(enzyme)on the surface of electrode,then the temperature-responsive electrochemical(bio)sensor is prepared.Electrochemical performance of the electrochemical(bio)sensor can be adjusted through changing environmental temperature,which opens up a new research direction for electrochemical sensing.The main research content and results of this paper are shown below:(1)The temperature-sensitive PVCL homopolymer was synthesized via precipitation polymerization.The results showed that the PVCL homopolymer had the characteristic of temperature response,and the low critical solution temperature(LCST)was 30?.(2)A sandwich temperature-sensitive composite membrane: GO/PVCL/GO consisting of GO and PVCL were modified on glassy carbon electrode surface.The modified electrode showed obvious reversibly temperature-controlled “on-off”detection effect with the LCST temperature(30 ?)of PVCL as the boundary.Moreover CC and HQ in solution can be detected simultaneously during a wide concentration range by this modified electrode at the high temperature where the electrochemical reaction is in an “on” state.(3)A temperature-responsive PSG electrode was prepared by modifying Carboxylated multi-walled carbon nanotubes(MWCNT(COOH)),GO and PVCL on glassy carbon electrode.The electrochemical response signal of acetaminophen(AP)on the PSG electrode has a significant temperature-responsive "on-off" characteristic with 30? as the boundary.The peak current attenuation of AP on 36? is small when the solution temperature is changed between 26 ? and 36 ?,and thetemperature switch is reversible.In the “on” state,the PSG electrode can detect the AP in the solution over a wide linear range and a low detection limit.(4)Glucose oxidase(GOD)embedded in rGO-PVCL composite film was coated on the surface of glassy carbon electrode,and a GOD biosensor with temperature response was constructed.The rGO-PVCL composite membrane can provide GOD a good biological microenvironment and keep the biological activity of GOD.When the temperature is lower than 30?,the GOD activity is low,and when the temperature is higher than 30?,GOD has rapidly direct electron transfer on the electrode surface and good electrocatalytic activity to glucose in the solution.There are better precision and higher sensitivity for GOD in detecting glucose at high temperature.