Synergistic Contributions Of Fullerene, Ferrocene, Chitosan, Ionic Liquid Towards Improved Performance For Sensor

Biosensor has developed into a new analytical method of speediness, accuracy, real-time ,which has been widely applied in the clinical diagnosis,environmental monitoring,and food sanitation control etc.The development of simple and effective strategies for the construction of interface on the sensor substrate surface is a crucial step in the design and fabrication of biosensors,which not only directly influences the performance of biosensor,such as sensitivity,detection range and stability etc,but also lays a foundation for development and application of biosensors.The dissertation focuses on developing new ways for fabricating novel biosensor;prepare biosensors with high sensitivity and long term stability.Because of the excellent performance in bioconsistent,catalytic abilities,conductibility etc,nano-material were widely used in electrochemical biosensors. Ferrocene (Fc) and its derivatives have been used as mediators in the development of biosensors due to their properties of relatively good electrochemical reversibility and stability at low potential. Ionic liquids become one of the most promising materials due to their unique properties of good conductivity ,high chemical and thermal stability ,wide electrochemical windows etc.The biopolymer chitosan (CS) is a kind of matrix for enzyme immobilization with attractive properties that include excellent film—forming ability,good adhesion and biocompatibility .Based on the fundamentals mentioned above, the dissertation imported C₆₀,Fc,ILs and CS to fabricate modify electrodes.The main works are included as follows:Choose a serious of ionic liquid contains [OMIM][PF₆],[BMIM][PF₆],[DBIM][PF₆],[DBIM]Br and [DBIM][TF2N] according to different polarities ,different anionic and cationic. Firstly,the physical properties of polarity and viscosity were determined .The glucose can produce hydroxide under the action of glucose oxidase(GOx),then glucose oxidase can make fluorescein fade and fluorescence quenched under the the catalytic action of horseradish peroxidase (HRP).Based on the phenomenona,selective fluorescence method is invented to determine the glucose content . Effect of different ionic liquid on catalysis performance and molecular conformation of GOx were investigated by fluorescence spectra .An ingenious approach for the fabrication of a promising glucose sensor, GOx/C₆₀/Fc/CS-IL was development, that exploits the synergistic beneficial characteristics of fullerene (C₆₀),ferrocene (Fc),chitosan (CS) and ionic liquid (IL). Cyclic voltammetry, impedance spectroscopy and chronoamperometry were used to evaluate the performance of biosensor. Because direct electron transfer between GOx and the electrode was achieved, the biosensor exhibits a high sensitivity (237.26 nA/nmol·L^-1cm^-2), low detection limit (S/N=3) (3×10^-9 mol·L·1),and wide calibration range (1×10^-8～1×10^-5 mol·L·1).The apparent Michaelis-Menten constant of GOx on the composite medium, 0.03 mmol·L·1, shows excellent bioelectrocatalytic activity of immobilized enzyme toward glucose oxidation. The modified biosensor is relatively insensitive to electroactive interfering species such as ascorbic acid, and uric acid which are commonly found in blood samples.Developed an approach for the fabrication of a promising label-free electrochemical impedance immunosensor for detection of paraquat, Ab/C₆₀-FC-CS-IL, that exploits the synergistic beneficial characteristics of fullerene (C₆₀),ferrocene (FC),chitosan (CS) and ionic liquid (IL) for the antibody of paraquat (Ab). Cyclic voltammetry and electrochemical impedance spectroscopy were used to investigate electrochemical characteristics of the sensor, respectively. Since synergistic contributions of fullerene, ferrocene, chitosan and the ionic liquid towards improved performance for a paraquat sensor, the sensor exhibits a good repeatability (RSD=1.5%), selectivity and good long-term stability (6 months). When the concentration of paraquat is between 3.89×10^-11 and 4.0×10^-8 mol·L^-1, the electron transfer resistance of the sensor will increase linearly with a correlation coefficients of 0.999.it was satisfactorily applied to determination of paraquat in meconium samples.