Fabrication Of Novel Graphene-based Composites Modified Enzymeless Electrochemistry Sensors For Pesticide Determination

In modern agriculture, extensive use of organophosphates pesticides (OPs) for pest control has raised serious public concern regarding the healthiness, environment and food safety. They disrupt the cholinesterase enzyme that regulates acetylcholine (AChE), which often causes respiratory paralysis and death. Therefore, rapid determination and reliable quantification of trace level of OPs have become increasingly important for homeland and health protection.Traditional analysis of OPs is routinely carried out by gas/liquid chromatography or mass spectroscopy. These methods often require complicated pre-treatment steps, extensive labor resources, and are not applicable for on-site determination. Over the past few years, enzyme-based inhibition/noninhibition biosensors, especially based on various electrochemical transducers, have emerged as a promising alter-native to detect pesticides. Nevertheless, the operational conditions are mostly limited by the denaturation of enzymes.To overcome this problem, a nonenzymatic sensor, stripping voltammetric analysis combined with solid phase extraction (SPE) of OPs appears to be an ideal and highly sensitive technology. As well known, solid phase extraction (SPE) is a most popular method for sample preparation and separation. For strip-ping analysis, the design of solid-phase extractor is a considerably critical issue, directly related with the stripping peak signal.Based on the above knowledge, we fabricated three novel graphene-based composites modified enzymeless electrochemistry sensors for ogranophorus pesticide determination:1. We described an enzymeless OPs sensor using Au nanoparticle-decorated graphene hybrid nanosheets. The resulting nanocomposite combines the advantages of AuNPs (extraordinarily catalytic activity, good conductivity) together with the graphene nanosheets (high surface areas, high electrical conductivity). It is expected to dramatically facilitate the enrichment of OPs and realize their rapid, stable and sensitive stripping voltammetric detection.2. We developed a facile approach to prepare a novel composite of zirconia nanoparticles-decorated graphene hybrid nanosheets for an enzymeless methyl parathion sensor. The nanocomposite matrix, combining the advantages of ZrO2NPs (a strong affinity to phosphoric moieties, high surface areas) with the graphene nanosheets (high surface areas, high electrical conductivity), greatly facilitated the preconcentration of MP with the peak current response greatly enhanced. The resulting sensor showed both good reproducibility and ideal stability. 3. We described an enzymeless methyl parathion (MP) sensor based on MP-imprinted porous silicate film coated with graphene. The composite, combining the advantages of MP-imprinted silicate film (due to its high specificity) with the graphene nanosheets (high electrical conductivity), exhibits high degree of selectivity and sensitivity towards the detection of MP.