A disposable biofilm-modified amperometric biosensor for the sensitive determination of pesticide biotoxicity in water

In the present study, a disposable biofilm-modified amperometric microbial sensor was developed and employed as an analytical tool for evaluating the biotoxicity of pesticides and real wastewater. The proposed biotoxicity biosensor was fabricated by using a polymeric disposable biofilm, which was prepared by immobilizing the pretreated S. cerevisiae cells (as a highly active biocatalyst) on a combination of polyvinyl alcohol (PVA) hydrogel and sodium alginate crosslinked by CaCl2 as a matrix at the electrode surface. It was found that the S. cerevisiae pretreated with alcohols is needed for increasing the response sensitivity of the microbial sensor; therefore, the effects of the treated reagents, concentration and treating time, etc., on the performance of the biosensor were optimized. Atomic force microscopy (AFM), flow cytometry (FCM), as well as the electrochemical response, were employed to investigate the morphology characteristics, cells viability and electrochemical characteristics, respectively. 3,5-Dichlorophenol (DCP) was taken as the reference toxicant. Pesticide solutions, including Acephate, Ametryn and Thiram were selected as model toxicants. The biotoxicity of four kinds of real wastewater was also determined by this amperometric microbial sensor. The traditional parameter of 50% inhibitory concentration (IC50) was measured within 30 min and the results obtained were better than those of other toxicity bioassays reported. The microbial biosensor prepared is a sensitive, rapid, convenient and cheap alternative to toxicity screening of chemicals and real wastewater.