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A glassy carbon electrode modified with graphene and tyrosinase immobilized on platinum nanoparticles for sensing organophosphorus pesticides |
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| Authors: | Tao Liu Minrong Xu Huanshun Yin Shiyun Ai Xiangjin Qu Shanshan Zong |
| Institution: | 1. College of Chemistry and Material Science, Shandong Agricultural University, Taian, Shandong, 271018, China |
| Abstract: | An amperometric biosensor is described for the detection of organophosphorus pesticides. It is based on the enzyme tyrosinase immobilized on platinum nanoparticles and the use of a glassy carbon electrode modified with graphene. Tyrosinase was immobilized on the electrode surface via electrostatic interaction between a monolayer of cysteamine and the enzyme. In the presence of catechol as a substrate, the pesticides chlorpyrifos, profenofos and malathion can be determined as a result of their inhibition of the enzyme which catalyzes the oxidation of catechol to o-quinone. Platinum nanoparticles and graphene effectively enhance the efficiency of the electrochemical reduction of o-quinone, thus improving sensitivity. Under optimum experimental conditions, the inhibition effect of the pesticides investigated is proportional to their concentrations in the lower ppb-range. The detection limits are 0.2, 0.8 and 3?ppb for chlorpyrifos, profenofos and malathion, respectively. The biosensor displays good repeatability and acceptable stability. A tyrosinase-based biosensor was developed for determining organophosphorus pesticides. The biosensor owned high sensitivity by combining platinum nanoparticles and graphene, and the immobilized tyrosinase had a great affinity to catechol. Low detection limits and reasonable liner ranges were obtained. The biosensor also displayed good repeatability and acceptable stability. |
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