RESUMO
An ultra-sensitive electrochemical biosensor was successfully developed for rapid detection of pirimiphos-methyl in olive oil, based of genetically-engineered acetylcholinesterase (AChE) immobilization into electrospun chitosan/poly (vinyl alcohol) blend nanofibers. Due to their unique properties such as spatial structure, high porosity, and large surface area, the use of nanofibers allowed improving the biosensor response by two folds. The developed biosensor showed a good performance for detecting pirimiphos-methyl, with a limit of detection of 0.2nM, a concentration much lower than the maximum residue limit allowed set by international regulations (164nM). The biosensor was used for the detection of pirimiphos-methyl in olive oil samples after a simple liquid-liquid extraction, and the recovery rates were close to 100%.
Assuntos
Acetilcolinesterase/química , Técnicas Biossensoriais/métodos , Quitosana/química , Membranas Artificiais , Azeite de Oliva/química , Compostos Organotiofosforados/análise , Álcool de Polivinil/química , Acetilcolinesterase/metabolismo , Acetiltiocolina/química , Animais , Eletricidade , Electrophorus , Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo , Contaminação de Alimentos/análise , Nanofibras/químicaRESUMO
An ultra-sensitive screen-printed biosensor was successfully developed for phosmet detection in olive oil, based on a genetically-engineered acetylcholinesterase (AChE) immobilized in a azide-unit water-pendant polyvinyl alcohol (PVA-AWP)/Fe-Ni alloy nanocomposite. Fe-Ni not only allowed amplifying the response current but also lowering the applied potential from 80 mV to 30 mV vs Ag/AgCl. The biosensor showed a very good analytical performance for phosmet detection, with a detection limit of 0.1 nM. This detection limit is lower than the allowable concentrations set by international regulations. In addition to the good reproducibility, operational and storage stability, the developed biosensor was successfully used for the determination of phosmet in olive oil samples without any laborious pre-treatment. The phosmet recovery rate was about 96% after a simple liquid-liquid extraction.
Assuntos
Acetilcolinesterase/química , Técnicas Biossensoriais/métodos , Enzimas Imobilizadas/química , Ferro/química , Nanocompostos/química , Níquel/química , Azeite de Oliva/análise , Fosmet/análise , Álcool de Polivinil/química , Acetilcolinesterase/genética , Ligas/química , Enzimas Imobilizadas/genética , Limite de Detecção , Extração Líquido-Líquido , Reprodutibilidade dos TestesRESUMO
Oxovanadium complexes are presented as new labels for the development of electrochemical immunosensors. The concept was successfully applied to the accurate detection of estradiol, an emerging environmental pollutant, at concentrations ranging from 4 ng L(-1) to 5 µg L(-1).
