The Fabrication And Application Of Electrochemical Aptasensor Based On The Carbon Nanocomposites

Kanamycin is an aminoglycoside antibiotic which is produced by the fermentation of streptomyces kanamyceticus. It is used to treat a variety of infections by inducing mistranslation and indirectly inhibiting translocation during protein synthesis. The abuse of kanamycin can cause serious side effects, such as loss of hearing, toxicity to the kidneys, and allergic reactions to the drugs. Therefore, it is critical to detect kanamycin in food products in order to avoid exceeding intake of kanamycin.Electrochemical aptamer-based sensors(aptasensors) based on specific interaction between aptamer and target molecules have attracted considerable interest for the highly sensitive and specificity detection of antibiotics. Meanwhile, the modifying technology of the electrode is the crucial step, which affects the signal intensity of the electrochemical detection and the immobilization amounts of biomolecules. In this paper, nanomaterials, such as multi-walled carbon nanotubes, graphene, nanoporous Pt Ti and hierarchical nanoporous PtCu,were used to modify the electrode and the sensor was prepared for kanamycin detection.Some researches were made as follows:1. A novel electrochemical aptasensor based on MWCNTs-BMIMPF6 and amino functionalized graphene nanocomposites film for determination of kanamycinFirstly, a novel composite film consisted of multi-walled carbon nanotubes(MWCNTs)and room temperature ionic liquid(RTIL) of 1-butyl-3-methylimidazolium hexafluorophosphate(BMIMPF6) was fabricated on the surface of a glass carbon electrode(GCE). The synergy mechanism between MWCNTs and RTIL has been discussed. Secondly,amino functionalized graphene nanocomposite(GR-CO-NH-CH2-CH2-NH2) was modified on the first film, which could greatly improve the conductivity of the electrode. The properties of the aptasensor were characterized by the electrochemical methods. Under the optimum conditions, the electrochemical aptasensor exhibited a wide linear range for kanamycin from5.8×10-4-58.2 ?g/mL with a low limit of detection of 5.1×10-4 ?g/mL(S/N=3). The as-prepared aptasensor showed high sensitivity, reproducibility and stability. Finally, the proposed electrochemical aptasensor was successfully applied for the detection of kanamycin in a real sample.2. A novel electrochemical aptasensor for ultrasensitive detection of kanamycin based on MWCNTs-HMIMPF6 and nanoporous PtTi alloyA novel aptasensor based on a novel composite film consisting of multi-walled carbon nanotubes(MWCNTs), ionic liquid(IL) of 1-hexyl-3-methylimidazolium hexafluorophosphate(HMIMPF6), and nanoporous PtTi(NP-PtTi) alloy was constructed for ultrasensitive detection of kanamycin. The NP-PtTi alloy was successfully fabricated by a simple dealloying of PtTiAl source alloy in HCl solution. A number of factors affecting the activity of the aptasensor have been discussed and optimized. Under the optimized conditions,the proposed aptasensor provided a linear range of 0.05-100 ng/mL with a low detection limit of 3.7 pg/mL. The resulting aptasensor was successfully applied for kanamycin detection in real milk samples. Thus, this aptasensor might provide the potential applications for kanamycin detection in the field of food analysis.3. A novel signal amplification strategy of an electrochemical aptasensor for kanamycin,based on thionine functionalized graphene and hierarchical nanoporous PtCuIn this work, an ultrasensitive electrochemical aptasensor was developed using thionine functionalized graphene(GR-TH) and hierarchical nanoporous(HNP) PtCu alloy as biosensing substrates for the first time. HNP-Pt Cu alloy with controllable bimodal ligament/pore distributions was successfully prepared by two-step dealloying of a well-designed PtCuAl precursor alloy combined with an annealing operation. GR-TH composite was synthesized by one-step reduction of graphene oxide(GO) in TH solution.Under the optimized conditions, the proposed aptasensor exhibited a high sensitivity and a wider linearity to kanamycin in the range 5×10-7-5×10-2 ?g/mL with a low detection limit of0.42 pg/mL. The as-prepared aptasensor also displayed a satisfying electrochemical performance with good stability, selectivity and reproducibility. In addition, this aptasensor was successfully used for the determination of kanamycin in animal derived food.