Biosensor Based On Gold Nanoparticles Composite For Detection Of Organophosphorous

Organophosphorous pesticides (OPs) are extensively used in the agricultural industry,but it is caused serious pollution to the environment and harmful for human health. Thetraditional techniques for OPs monitoring such as chromatography has advantages ofqualitative, quantitative, accurate and high sensitivity, but these methods require professionaloperators, expensive instrumentation and complicated pretreatment steps, and are not suitablefor field inspection. Electrochemical detection are fast response, simple operation, highsensitivity and make it is possible for on-site pesticide detection，so the method have beenextensively studied in field of OPs detection. Since gold nanocomposite material have themany advantages, such as good electrical conductivity, large specific surface area, strongadsorption and good biological compatibility. On the one hand, the electrode modified withgold nanoparticles composite can detect directly OPs with electrochemical characteristics. Onthe other hand, we study the AChE biosensor preparation using gold nanoparticles compositeas carriers for the immobilization of enzymes. The enzyme biosensor has strong stability andhigh sensitivity. The results are as follows:1.In order to improve the electrode sensitivity, gold nanoparticles–polyaniline-multi-walled carbon nanotubes (AuNPs-PANI-MWCNTs) are prepared andstudy the electrochemical behavior of parathion on the modified electrode which has theproperties of oxidation reaction on the surface of the electrode. The current of parathion wasproportional to its concentration ranging from30to200μmol/L with a detection limit of6.04μmol/L.2.A amperometric acetylcholinesterase (AChE) biosensor for quantitative determinationof parathion is developed based on Au nanoparticles-polyaniline-multiwalled carbonnanotubes (AuNPs-PANI-MWCNTs) nanomaterial modified electrode. In this experiment,using glutaraldehyde as crosslinking agent,1%bovine serum albumin (BSA) as a protectiveprotein, from0.2to2n mol/L and8to100n mol/L, the enzyme inhibition rate is proportionalto parathion concentration, with a detection limit of0.062n mol/L. 3.The AuNPs-CS nanocomposites are prepared, according to St ber synthesis of carbonspheres (CS) and growth of gold on the surface of CS by chemical reduction method. TheAChE/AuNPs-CS/NBDD electrochemical biosensor is developed based on the AuNPs-CSnanocomposites used as carriers for the immobilization of enzyme. Under the optimizedconditions, from10-11to10-7mol/L, the enzyme inhibition rate is proportional to the negativelogarithm of chlorpyrifosconcentration, with a detection limit of1.29×10-13mol/L. In therange of10-12-10-6mol/L, the inhibition rate of enzyme and the negative logarithm of methylparathion concentration showed a good linear relationship, with a detection limit of4.9×10-13mol/L. The recoveries for cucumber juice samples obtained from theAChE/AuNPs-CS/NBDD sensor were calculated and found to be between86.6%and90%respectively for the detection of chlorpyrifos and methyl parathion.