Electrochemical Study Of Novel Ionic Liquid And Its Application In Biosensor

Five novel 1-butyl-2,3-dimethylimidazolium bis(tri(?)uoromethanesulfonyl)imide [butyl- DMimTFSI], 1-amyl-2,3-dimethylimidazolium bis(tri(?)uoromethanesulfonyl)imide [amyl- DMimTFSI], 1-octyl-2,3-dimethylimidazolium bis(tri(?)uoromethanesulfonyl)imide [octyl- DMimTFSI], 1-isooctyl-2,3-dimethylimidazolium bis(tri(?)uoromethanesulfonyl)imide [isooct yl-DMimTFSI] and 1-decyl-2,3-dimethylimidazolium bis(tri(?)uoromethanesulfonyl)imide [decyl-DMimTFSI] ionic liquids were synthesized successfully based on 1,2- dimethyl imidazole and toluene as a solvent using a similar temperature programming procedure. Then, chemical structure characteristics and physical properties were investigated after purified. The results were well coincide with their chemical structures characterized by FTIR and 1HNMR spectrum. They can dissolve in acetone, methanol and acetonitrile, but difficult to dissolve in water, toluene and carbon tetrachloride. The densities and viscosities of these five ionic liquids were 1.68,1.62,1.53,1.59,1.48 g/cm3 and 100.6,116.2,134.6,207.8,189.1 cP respectively at 25℃. It was found that densities were decreased and viscosities increased with increasing the carbon chain of the substitute group which disclosed that ionic liquids with bis(tri(?)uoromethanesulfonyl)imide as anion own lower viscoty and higer thermal stability than that of hexafluorophosphate.Conductivity and electrochemical window tests were done via conductivity meter with platinum electrode and Linear sweeep voltage method. It demonstrated that these five ionic liquids all have a higher conductivity 3320μs/cm,2380μs/cm,1400μs/cm,880μs/cm and 940μs/cm respectively and a wider electrochemistry window which are all above 5 V at 25℃than traditional 1-butyl-3-methylimidazole hexafluorophosphate ionic liquid. Otherwise, it also indicated that the conductivity increased with viscosity decreased.The actual work environment of ionic liquid in immunbiosensor was simulated by a battery model, and the cyclic stability and electronic conduction of ionic liquids were studied through dynamic cycles, cyclic voltammetry and ac impendance spectroscopy. The initial cycling test demonstrated that the cyclic stabilities of buyl-DMimTFSI and amyl-DMimTFSI whose charge/discharge capacities attained 145 and 152.6 mAh/g were better than three other ionic liquids, the cyclic voltammetry after 120 cycles further indicated the cyclic stability of amyl-DMimTFSI. Ac impendance values of butyl-DMimTFSI, amyl-DMimTFSI, octyl-DMimTFSI, isooctyl-DMimTFSI and decyl-DMimTFSI after 1 cycle and 120 cycles were 1510 (?), 1223 (?), 2775 (?), 12300 (?), 3127 (?) and 2020 (?), 1890 (?), 4380 (?), 12258 (?), 4258 (?) respectively, the result disclosed that amyl-DMimTFSI has the fastest electron transport. So amyl-DMimTFSI has the best electrochemical performance. Moreover, the hermetical environment can ensure the veracity of tests.An ingenious approach for the fabrication of a promising deoxynivalenol immunbiosensor, Ab/IL-CS-G-Fc-GCE, that exploits the synergistic beneficial characteristics of ionic liquid amyl-DMimTFSI (IL), chitosan (CS), Graphene (G) and ferrocene (Fc) for deoxynivalenol Antidody. Cyclic voltammetry, impedance spectroscopy and were used to evaluate performance of the biosensor, respectively. Since efficient electron transfer between Antidody and the electrode was achieved, the biosensor exhibits a low detection limit (0.0003 ng/ mL, S/N=3), excellent long-termstability (5 weeks) and good repeatability (n=10, RSD=3.5%). When the concentration of deoxynivalenol is between 0.001ng/mL and 0.3ng/mL, the electron transfer increase resistance(△Ret) of the sensor and the concentration of deoxynivalenol (C) linear equation is△Ret (K?) = 1.0061+66.127C (ng/mL) with a correlation coefficient of 0.9909. The proposed method is very high sensitivity, selectivity and stability, it has been successfully applied to determination of trace deoxynivalenol in beer with a spiked recovery between 97.8 % and 101.5 %, which laid a good foundation for biosensors in food safety testing field.