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Novel Nano-Biosensor for Rapid Detection of Environmental Hormones

Author: JiangChunHuan
Tutor: DaiZhiFei
School: Harbin Institute of Technology
Course: Biomedical Engineering
Keywords: Acetylcholinesterase Biosensor Organophosphorus pesticides Multi-walled carbon nanotubes
CLC: TP212.3
Type: Master's thesis
Year: 2011
Downloads: 60
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Organophosphorus pesticides (OPs) is a very wide range of applications in the agricultural pests killing agent, which has a strong inhibitory effect on the nervous system of the organism. Prolonged human exposure to organophosphate pesticides vivo acetylcholinesterase (AChE) cause irreversible loss of activity, a lot of accumulation of its substrate acetylcholine (a neurotransmitter), which led to a series of nerve-like illness. Rapid and sensitive detection the organophosphorus pesticide content in the environment is particularly important for food safety and human health. Acetylcholinesterase-based electrochemical biosensor has good selectivity, sensitivity, low cost, and the advantages of miniaturization, etc., and is widely used in the detection of organophosphorus pesticide residues (based on the principle of enzyme inhibition). However, such sensors generally require a higher potential ( 7 00 mV) the oxidized enzymatic product - thiocholine detected current is generated at a high potential, many substances are prone to oxidation reaction, if some impurities in the selective oxidation will generate noise signal, the impact sensor. Therefore, in recent years, a large number of studies dedicated to reduce the working potential of the biosensor in order to improve its selectivity. Of this study was to construct an acetylcholinesterase biosensor based on Nafion-multi-walled carbon nanotubes (MWNTs) composites. This composite material has excellent electrical catalytic and enzyme immobilization performance, therefore, the working potential of the bio-sensor can be effectively lower, and thus effectively increase the selectivity of the biosensor. The biosensor also has good sensitivity, stability and detection limits. In addition to methods for their preparation is very simple, requires only twice dried dispenser can. Polyelectrolyte Nafion as the MWNTs dispersion medium prepared having a good dispersibility of the Nafion-MWNTs composite. Nafion as fixed matrix AChE fixed on Nafion-MWNTs/GCE surface to build one kind of AChE / nafion-MWNTs / GCE biosensor, and the experimental conditions were optimized. AC impedance results show Nafion-MWNTs composite membrane can significantly reduce the electron transfer resistance of the electrode (RCT), and can efficiently catalyze the electrochemical probe. Catalytic performance due to its excellent electrical, Nafion-MWNTs/GCE mercapto choline oxidation potential fell to about 300mV, and significantly improve its oxidation current. The chronoamperometry characterization results demonstrate AChE / Nafion-MWNTs / GCE able the 0.02mM 1 .1 mM range of linear response of the substrate - acetylthiocholine sensitivity 10.303nA · μM -1 . Calculated in this experiment the immobilized acetylcholinesterase Michaelis constant 0.57mM. The optimized sensor preparation conditions and experimental conditions, the use of the AChE / nafion-MWNTs / GCE sensor detects organophosphate pesticides - paraoxon content. Linear detection range of 10 -11 of 1 0 -8 g / mL, the detection limit of 3 × 10 -12 g / mL, the relative recoveries of 95% 1 07%.

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