Nanomaterials Based Electrochemical Biosensors And Their Application In Pesticide And Thiols Detection

Ultra-sensitive detection of organophosphorous pesticides (OPs) has attracted great attention in the past couple of decades not only because they are widely used in the agricultural industry, but also some of them have very long lifetimes and may find their way in our food and water supplies. In short, for environmental protection and human health safety purposes, it is necessary to restrict the recommend level of OPs and at the same time develop sensitive and fast technology to monitor OPs infield.In this paper, several nanomaterials based electrochemical biosensors are developed for the ultrasensitive detection of OPs. The details are as follows:First, the surface hydrophilicity of the Au-PDDA-PB nanocomposite was finely controlled in the static water contact angle range of25.6-78.1°by adjusting the ratio of gold nanoparticles to PDDA-PB. On an optimized hydrophobic surface, the AChE adopts an orientation with both good activity and stability, which has been proven by electrochemical methods. The biosensor shows significantly improved sensitivity to monocrotophos and ultra-low detection limit of0.8pg/mL.Second, A three-dimensional interpenetrating electrochemically reduced graphene oxide and Nafion network (Er-GRO-Nafion) was prepared to immobilize acetylcholinesterase and for ultra-low potential detection of dichlorvos (+9mV). The Er-GRO-Nafion nanocomposite could effectively promote electron transfer, facilitate the access of substrates to active center, and immobilize AChE stably. The biosensors shows may have great prospective to be used for OPs monitoring.Third, Electrochemical reduced (3-cyclodextrin dispersed graphene was developed as a sorbent for the preconcentration and electrochemical sensing of methyl parathion (MP). Benefited from the ultra-large surface area, large delocalized π-electron system and the superconductivity of β-CD-graphene, large amount of MP could be extracted on P-CD-graphene modified electrode via strong π-π interaction and exhibited fast accumulation and electron transfer rate. The method may open up a new possibility for the widespread use of electrochemical sensors for monitoring of ultra-trace OPs.At the end, Selective detection of cysteine in serum samples was achieved on a graphene nanoribbon (GNR) and Nafion nanocomposite modified electrode with high precision. The electrochemical sensor showed strong antifouling ability, good stability and selectivity. It could effectively exclude the interferences from other kinds of biothiols and the biological relevant species, thus had great perspective for in vivo analysis of biological samples.