Abstract
Carbon nano-onions are emerging electrode materials in biosensing due to their high conductivity and biocompatibility. Phenoxy-based herbicides are a source of environmental contamination that can be detected using their property to inhibit the activity of some enzymes. Here we report a biosensor based on peroxidase immobilized on carbon nano-onions in a cyclodextrin polymer matrix for the amperometric detection of 2,4-D and 2,4,5-T. The inhibition mechanism of 2,4-D and 2,4,5-T on peroxidase activity was first elucidated by activity measurements and molecular docking. The biosensor was characterized by electrochemical and microscopy methods and applied to the amperometric detection of these herbicides. The incorporation of carbon nano-onions enhanced the sensitivity of the biosensor and improved its stability and repeatability. The application of the developed biosensor to the detection of 2,4-D in soil and 2,4,5-T in river water samples is also reported.
Highlights
Carbon nano-onions are emerging electrode materials in biosensing due to their high conductivity and biocompatibility
2,4-D and 2,4,5-T on peroxidase activity was first elucidated by activity measurements and molecular docking
Oxidized carbon nano-onions (CNOs) were prepared by oxidation of CNOs (100 mg) with 10 mL of HNO3 /H2 SO4 (1:3 v/v) for one hour at room temperature [21]. 2,4-D, 2,4,5-T, phosphate-buffered saline (PBS), maleimide activated peroxidase from horseradish (M-HRP, 200 units mg−1 ) and 3,30,5,50 -tetramethylbenzidine (TMB) Liquid Substrate System for ELISA were purchased from Merck
Summary
Carbon nanomaterials emerged as one of the most suitable materials in biosensing due to a combination of chemical versatility and electronic properties [1]. CNOs are formed by concentric graphitic layers with increasing diameters and possess a distinctive combination of high conductivity and biocompatibility, among other interesting properties [6] They can be modified by a wide range of functional groups and incorporated in composite materials with organic or inorganic polymers for a wide range of applications, including energy storage [7] and biomedicine [8], among others. Phenoxy herbicides, such as 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5trichlorophenoxyacetic acid (2,4,5-T), are synthetic analogs of auxin plant growth hormones derived from phenoxyacetic acid [9]. The effect of the CNOs on the analytical parameters and biosensor stability was studied
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