An electrochemical biosensor (denoted as AChE/Au/MWNT/GCE) was prepared based on immobilizing acetylcholinesterase(AChE)on the surface of gold nanoparticle and multiwall carbon nanotube (MWNT) modified glassy carbon electrode (GCE). Gold nanoparticles were dispersed on the surface of GCE coated with 0.8�g MWNT by cyclic voltammetry scanning between -0.2V to +1.0V(vs. SCE) at a scan rate of 50mV/s for 30 cycles from a fresh 0.1 M H2SO4 solution containing 5�10-3 M HAuCl4. The diameter of the gold nanoparticles was about 80�100 nm.Thiocholine was produced by the enzymatic reaction of acetylthiocholine used as substrate. The experimental results of cyclic voltammetry indicated that thiocholine can be electrocatalytically oxidized at the electrodes to produce a sensitive anodic peak at about +0.85V. The response sensitivity of thiocholine at AChE/Au/MWNT/GCE was obviously higher than those at AChE/Au/GCE or AChE/MWNT/GCE, which demonstrate that gold nanoparticles and multiwall carbon nanotubes possess synergetic effect in electrocatalytic oxidation of thiocholine.The biosensor was used to determine organophosphorus pesticides by square wave voltammetry. The detection limits of methyl parathion, ethyl parathion and omethoate were 8.0�10-7 M, 3.2�10-6 M and 1.4�10-5 M, respectively. The good stability and high sensitivity that the biosensors possessed means the method could be a promising way for the determination of organophosphorus pesticides in real samples.The authors thank the financial support from the Beijing Natural Science Foundation (No. 8102009), the Key Program of Science of and Technology of Beijing Municipal Education Commission (No. KZ201110005006).

Biosensors for organophosphorus pesticides based on gold nanoparticle and carbon nanotube modified electrodes

243rd National Meeting (2012)

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