Construction And Application Of Electrochemical Sensing Interfaces For Endocrine Disrupting Chemicals

The environmental problems caused by endocrine disrupting chemicals（EDCs）have received widespread attention,and it is quite important to establish highly sensitive methods for the detection of EDCs.Electrochemical/photoelectrochemical sensors have obtained increasing applications in environmental analysis due to their advantages,such as high sensitivity,fast analysis,low cost,simple operation,easy miniaturization and intelligence.Researches on the preparation of new sensing materials and construction of novel sensing interfaces are crucial fordeveloping high-performance electrochemical/photoelectrochemical sensors.In this thesis,four sensing materials have been successfully prepared,namely molecularly imprinted polydopamine,gold nanopartilces functionalized poly（sulfosalicylic acid）,PVP-functionalized black phosphorus nanosheets and graphene@two-dimensional black phosphorus nanocomposites.Then,three kinds of electrochemical sensing interfaces and one kind of photoelectrochemical sensing interface have been contructed.Their sensing performance and catalytic sensitization mechanisms have been investigated in detail.As a result,highly-sensitive and specific new methods have been developed for three kinds of EDCs,which successfully applied in the analsyis of environmental samples.The main studies are as follows.（1）3,3′,5,5′-Tetrabromobisphenol A（TBBPA）is one of the most widely used brominated flame retardants with significant endocrine disrupting effects.In this chapter,using dopamine as monomer and TBBPA as template,electropolymerized molecularly imprinted polydopamine film（e PDA-MIP）were prepared in situ on the electrode surface by cyclic voltammetry scanning（-0.50–0.50 V）.The influences of the concentration of template molecule,cyclic scan cycles and scan rate on the electrochemical enhancement effects of e PDA-MIP were investigated,and the optimal preparation conditions were obtained.Based on the specific recognition effect of e PDA-MIP,a new electrochemical method for the selective detection of TBBPA has been established.The linear range is from1.0 to 50.0 n M(10^-9 mol/L),and the detection limit is 0.27 n M.This method was applied in the analysis of plastic e-waste samples,and the relative error was less than±5.0%compared with results that obtained by high-performance liquid chromatography（HPLC）.（2）Constructing a TBBPA sensing interface with higher sensitivity and on-site analysis capability is more challenging.In this chapter,a gold nanoparticles funcationzliaed poly（sulfosalicylic acid）polymer（Au NPs-PSSA）was prepared in one step by cyclic voltammetry scanning（-1.00–1.60 V）in mixed solution of sulfosalicylic acid and chloroauric acid.The Au NPs-PSSA composite film provides larger response area,lower charge transfer resistance and higher enrichment efficiency for TBBPA oxidation,exhibiting remarkable synergistic enhancement effect.The effects of cyclic scan cycles,scan rate,p H value and enrichment time on the performance of Au NPs-PSSA were investigated.As a result,a sensitive,selective,simple and fast electrochemical sensing interface for TBBPA has been constructed,with a linear range of 0.10–10.0 n M and a detection limit of 25.0 p M(10^-12 mol/L).The method was applied to the analysis of wastewater samples,and the results were consistent with the values that obtained by HPLC.The preparation and renewing of this sensing interface can be conducted automatically by electrochemical methods,showing a good potential for online and automatic monitoring.This work further simplifies the electrode preparation process and improves the detection performance and the on-site analysis capabilityr for TBBPA.This electrochemical sensing interface is easy to prepare and more sensitive,thus showing better potential for on-site analysis of trace amounts of TBBPA.（3）The low exfoliation efficiency and poor stability of two-dimensional（2D）black phosphorus heavily limit its application in electrochemical sensing.In this chapter,the liquid-phase ultrasonic exfoliation preparation,stabilization and electrochemical sensing applications of 2D black phosphorus have been investigated.In the presence of polyvinylpyrrolidone（PVP）,the exfoliation efficiency of bulk black phosphorus in isopropanol is higher than that in ethanol,N-methyl pyrrolidone and N,N-dimethylformamide.The introduction of PVP significantly enhances the exfoliating efficiency and the stability of black phosphorus nanosheets（BPNS）.The black phosphorus nanosheets that exfoliated in the system of PVP and isopropanol（PVP@BPNS）exhibit larger electrochemical response area,faster electron exchange rate and stronger enhancement effect toward 4-nitrophenol oxidation.A highly-sensitive electrochemical sensing interface has been constructed for 4-nitrophenol using PVP@BPNS,with a linear range of 0.10 to 5.0μM and the detection limit of 28.0 n M.This sensing system was used for the analysis of wastewater samples,and the results were in good agreement with the values that obtained by HPLC.（4）The excellent semiconductor photoelectric properties of 2D black phosphorus（BP）indicates that it has promising application in photoelectrochemical sensing.Using cheap and accessible red phosphorus as the raw material,a nanocomposite of graphene and black phosphorus（Gr@BP）was prepared by in situ growing 2D BP on the surface of graphene（Gr）through a wet chemical method.The effects of reaction conditions on the morphology,crystal structure and photoelectrochemical properties of Gr@BP were investigated.Due to the formation of C-P and C-O-P covalent bonds between Gr and 2D black phosphorus,the stability,electrical conductivity and photoelectrochemical properties of 2D black phosphorus are significantly improved.In addition,an aptamer of bisphenol A was immobilized on the surface of Gr@BP to construct a specific and highly-sensitive photoelectrochemical sensing interface for bisphenol A.The linear range for bisphenol A was from 0.010 to 1000 n M,and the detection limit was 3.1 p M.It was used for the analysis of wastewater samples,and the results consisted with the values that obtained by HPLC.