Detection Of Phenolic Endocrine Disruptors By Electrochemical Sensors Based On Graphene Oxide

Endocrine disruptors(EDCs)are a class of exogenous chemicals that disrupt the endocrine system,including polychlorinated biphenyls(PCBs),perfluoroalkyl substances(PFOAs),bisphenols,and parabens,etc.They are often found in food,daily necessities or pesticides.Excessive accumulation in the body can interfere with hormonal feedback loops related to development,leading to diseases such as cancer,metabolic disorders,and reproductive disorders,and if released into the environment,it can also affect ecological balance.As a result,regulatory agencies around the world have set exposure limits and maximum allowable concentrations for various EDCs.To date,most detection work requires large-scale experimental equipment,but with the increase in the number of common EDC species,there is an urgent need to improve detection methods to be portable,fast,and inexpensive.Electrochemical sensors are sensing systems that convert the concentration response of target molecules into electrochemical signals for detection.They have the characteristics of high sensitivity and are suitable for low-cost,miniaturized designs,so they can be used for regular field tests and continuous remote monitoring.Therefore,this work adopts an electrochemical method,using the recognition system and conduction system of electrochemical sensors to convert the chemical signal of phenolic endocrine disruptors into electrical signals,so as to detect phenolic endocrine disruptors.Graphene/graphene oxide of a single layer of sp²carbon atoms is an attractive material in many research fields.Due to its high surface to volume ratio,excellent electrical properties,fast electron transfer,and strong mechanical properties,its unique two-dimensional structure often acts as a substrate to support metal or metal oxide nanoparticles as catalysts.Therefore,we conducted electrochemical detection of endocrine disruptors based on graphene for human health and environmental pollution research.However,according to several experiments and relevant literature,it was found that the anodic oxidation of phenolic EDC would form free radical intermediates and electropolymerization film to block the active site on the electrode surface and deactivate the electrode surface.Therefore,in order to avoid and solve this problem,the following three studies were carried out1.Electrochemical sensor based on electrochemical reduction of graphene oxide-nickel/nickel oxide for the detection of methyl parabenIn this work,the reduction of graphene oxide/nickel-nickel oxide was directly synthesized in situ on glassy carbon electrode by electrodeposition reduction method for the detection of methyl paraben(MP).The results show that doping of metal oxide can not only improve the stability of the electrode but also improves the sensitivity of the detection.Under optimized conditions,the sensor has a good linearity in the range of 5-60?mol·L^-1,and the lowest detection limit is 0.467?mol·L^-1.The sensor has good repeatability,high sensitivity,selectivity and stability.The developed sensor has been successfully applied to detect MP in contact lenses solutions with recoveries ranging from 97%to 109%.2.Renewable sensor based on reduced graphene oxide supported titania for the detection of methyl parabenSince the problem that the electrode is easily passivated in high concentration MP solution will seriously affect the reproducibility of the sensor.In order to solve this problem,this work prepared a renewable MP sensor by loading titanium dioxide on graphene oxide with good catalytic capacity and biocompatibility.In the process of analysis and detection,the photocatalytic degradation of organic compounds by titanium dioxide was used to activate and renew the electrode by uv light,which improved the reproducibility of the electrode.Later,the surface structure and electrochemical differences of the electrodes before and after activation were deeply studied.Ultimately,the sensor using this strategy showed a good linear relationship in the range of MP concentration of 5-1000?mol·L^-1,and the LOD was 1.65?mol·L^-1.The developed sensor successfully detected MP in cosmetics(moisturizing water),and the detection of different concentrations was carried out using the standard addition recovery method,and the recovery rate was between 98.6%and 107.1%.It is expected to be used in practical scenarios for rapid and quantitative detection of MP3.A renewable sensor based on palladium/titania-reduced graphene oxide for the detection of bisphenol AThe purpose of this work is to further improve the detection sensitivity of the materials prepared in the second work.Due to its excellent electrocatalytic activity and strong stability,Pd is often used as an ideal material for electrocatalysis.Therefore,Pd was added into the material based on Work 2 to achieve a high sensitivity detection of bisphenol A,with a linear range of 0.5 to 400?mol·L^-1and a LOD value of 0.16?mol·L^-1.The prepared sensor has certain anti-interference ability and repeatability,and finally BPA can be detected in actual samples(plastic bottles)with recoveries ranging from 93.5%to 102.3%.Therefore,a bisphenol A renewable sensor based on palladium/titania-reduced graphene oxide was successfully constructed.