Hemin Functionalized Graphene-Based Sensor Applied For Phthalic Acid Ester Detection

Phthalic acid ester（PAEs）is a commonly used plasticizer,which is mainly applied in plastic products,children’s toys,cosmetics,pesticides and other products.The existence of PAEs has brought many benefits to human.Meanwhile,it has brought severe pollution to the environment.Because of there is no chemical combination between PAEs and products,it’s easy to escape from the products and enter into air,soil,water.Then coming into the human body through breath,diet,skin contact and other ways,which will cause risks to human reproduction and immune systems,affect the growth of children,and also give rise to serious harm to aquatic animals.Therefore,it’s urgent to develop a fast and sensitive method for detection of PAEs.The colorimetric and electrochemical sensors have been widely used for detecting various target molecules due to their advantages such as simple operation,high sensitivity,fast analysis,easy miniaturization and so on.In this paper,different colorimetric and electrochemical sensors were constructed based on hemin-graphene（H-Gr）for detection of PAEs.The main achievements are as follows:（1）Colorimetric and electrochemical assay for dual-mode detection of di-2-ethylhexyl phthalate based on hemin-graphene nanocomposites.Di-2-ethylhexyl phthalate（DEHP）is a common PAEs,which can affects human health and increases the risk of cancer.This study reported a dual-mode method for DEHP detection based on H-Gr nanosheets and DEHP aptamer.The H-Gr nanocomposites,possessing inherent peroxidase-like activity,can catalyze the chromogenic substrate3,3′,5,5′-tetramethylbenzidine（TMB）to blue oxidized product（TMBox）.Meanwhile,H-Gr could be used as in situ probe for electrochemical detection.And DEHP aptamer is added as the biological recognition element.Owing to the specific recognition property of DEHP aptamer,the DEHP-aptamer complexes formed,which could inhibit the enzymatic activity and reduce the electrochemical signal of H-Gr.Thus,the colorimetric and electrochemical methods were developed for detection of DEHP with a linear relationship from 2.00×10^-10-1.00×10^-7 g/L and 1.00×10^-10-1.00×10^-7 g/L,respectively.We offer a sensitive,rapid and simple dual-mode strategy for the detection of DEHP.It showed promising practicability for detection of DEHP in water samples.（2）Construction of electrochemical sensor based on Pd@UIO-66-NH₂/H-Gr and detection of PAEs.In this study,we synthesized Pd@UIO-66-NH₂/H-Gr nanocomposites.Based on the good conductivity of graphene,the large surface area of UIO-66-NH₂ and the excellent catalytic ability of Pd nanoparticles,Pd@UIO-66-NH₂/H-Gr possessed good electrochemical performance.As electrode material,the Pd@UIO-66-NH₂/H-Gr was applied to construct electrochemical sensor,which was used for detection of three kinds of PAEs and their total amounts.When DEHP,dibutyl phthalate（DBP）or butyl benzyl phthalate（BBP）was added,the target molecules would adsorb on the surface of Pd@UIO-66-NH₂/H-Gr,which led to the impedance increased and the electrical signal decreased.The limit of detection（LOD）of DEHP,DBP and BBP is 1.00×10^-9 g/L,3.33×10^-9 g/L and 1.00×10^-9 g/L,respectively.The sensor is easy to operate and stable,which can be used for detection of PAEs in milk samples.It provides a new idea for the subsequent detection of PAEs.