Electrochemical Biosensor Based On Three-dimensional Nanomaterials And Ionic Liquids

Recently, ionic liquids, nanomaterials and their composite films have been used to fabricate modified electrodes and relevant researches have become a hot topic of modified electrode research. In this thesis, two types of new enzyme (and enzyme-free) modified electrodes based on three-dimensional ordered macroporous (3DOM) gold films and Cu2O nanospheres were fabricated to implement the determination of some small molecules. Details are as following:1. Enzyme sensor based on room temperature ionic liquids and three-dimensional ordered macroporous gold filmsBy casting method, four kinds of materials, room temperature ionic liquids (1-butyl-3-methylimidazolium tetrafluoroborate, [BMIM][BF4]), N, N-dimethylformamide (DMF), films and redox proteins, have been used to fabricate three-dimensional ordered macroporous (3DOM) gold film modified electrodes. The electrodes modified with hemoglobin (Hb), myoglobin (Mb) and Horseradish peroxides (HRP) showed a well-defined redution peak in cyclic voltammogram, which could be attributed to the redox of their similar active center. Lactate Dehydrogenase (LDH) modified electrode was used as an electrochemical sensor for the detection of lactate. The biosensor showed a wide dynamic range from 10～250 nM with a detection limit of 3.3 nM estimated at a signal-to-noise ratio of 3. Also, the effect of four modified materials, sol-gel, chitosan (Chi), Nafion and agarose hydrogel (Aga), on the elecectrochemical behaviors of the modified electrode were investigated. The experimental results indicated that the optimum material was Chi.2. The porous Cu2O nanosphere modified electrode for the detection of NADHPorous Cu2O nanospheres were synthesized via a sonochemical route with large pore size and specific surface area. This new nanomaterial was mixed with Nafion and DMF to drop on the surface of glassy carbon electrode, then a Cu2O/Nafion/DMF-GC electrode was modified. It is found that NADH can effectively accumulate at the electrode and cause a sensitive anodic peak at about 600 mV (vs. SCE) in pH 7.0 phosphate buffer solutions. Different solution pH influencing the response of the electrode, are optimized for NADH determination. Under pH=7.0 condition, the anodic peak current is linear to NADH concentration in the range of 0.01 to 20 mM. The detection limit is 334μM. In addition, a comparison is carried out between Cu2O-GC and Cu2O/Nafion/DMF-GC. Results showed that the Cu2O/Nafion/DMF-GC had better detection ability. This electrode also showed strong anti interference ability and good stability.