Molecularly Imprinted Sensors For Electrochemical Recognition Of Proteins Based On Functional Ionic Liquids

Ionic liquid is supposed to be of great potential in multitudinous of applicationdue to the facile modulation on its cations or anions with various functional groups,which endows the ionic liquid with specific functions and properties. While apolymerizable ionic liquid monomer is polymerized, the polymerized ionic liquid notonly inherits the unique properties of ionic liquid but also provides novel propertiesand functions such as improving chemical stability, durability and physical rigidity,minimizing the mass leakage. In the last few years, polymerized ionic liquids or inother words ionic liquid polymers have attracted grate interests of research.In this dissertation, two kinds of amino-functionalized ionic liquids have beensuccessfully synthesized. One is3-(3-aminopropyl)-1-vinylimidazoletetrafluoroborate (APVIMBF4) and the other is3-{3-[(2-aminoethyl)amino]propyl}-1-vinylimidazole bromide (AEAPVIMBr).1H nuclear magnetic resonancespectroscopy, Fourier transform infrared spectroscopy and ultraviolet-visiblespectrophotometer were applied to identify the chemical construction of the ionicliquids. Both of the ionic liquids are able to form hydrophilic gel polymers throughthe polymerization of ionic liquid bearing vinyl.The molecular imprinting technology is a method to fabricate polymers whichpossess high selectivity towards template protein. In the first step, functionalmonomer, cross linker and template protein were mixed thoroughly, and usinginitiator to produce free radical to initiate the polymerization to obtain a polymer. Inthe second step, template protein was completely removed from the polymer to give aimprinted polymer. In order to enhance the combination of ionic liquid and the surfaceof glass carbon electrode (GCE), a carboxylic multi-walled carbon nanotube(MWCNT) membrane was modified on the glass carbon electrode. Adding carbonnanotubes also enhance the mechanical strength. Two electrochemical sensors basedon molecular imprinting materials have been prepared based on the two ionic liquidsalready described in the above.Selectivity of the as-prepared molecularly imprinted sensors was investigated.Sensing performance towards the template protein was also examined. Main contentof the dissertation was presented as following: (1)3-Aminopropyl-1-vinylimidazole tetrafluoroborate ionic liquid and bovineserum albumin (BSA) were thoroughly mixed in the Tris-HCl buffer solution. UsingN,N’-Methylenebisacrylamide as crossing linker and ammonium persulfate asinitiator, a BSA imprinted polymer was formed on the surface of MWCNT modifiedglassy carbon electrode through a radical polymerization.(2)3-{3-[(2-aminoethyl)amino] propyl}-1-vinylimidazole bromide and myoglo-bin from skeletal muscle were thoroughly mixed in phosphate buffer solution. UsingN, N’-Methylenebisacrylamide as crossing linker and ammonium persulfate asinitiator, a myoglobin imprinted polymer was fabricated onto glassy carbon electrodesurface through radical polymerization.Using K3[Fe(CN)6]/K4[Fe(CN)6] as probes, investigations have been conductedby cyclic voltammetry to determine the efficiency and the selectivity of themolecularly imprinted polymers. The results demonstrated that both of themolecularly imprinted polymers showed good selectivity and that ionic liquids can beapplied to the molecular imprinting technology to improve protein sensing. Thecurrent response of the BSA imprinted sensor to BSA is found linearly related with itsconcentration in the range of1.5010-9~1.5010-6mol L-1. The limit of detectionwas estimated to be3.9110-10mol L-1(S/N=3). The linear response of the myoglobinimprinted sensor is in the range of6.0010-8~6.0010-6mol L-1. The detectionlimit was estimated to be9.6810-9mol L-1(S/N=3).