title: Electrochemical immunosensor for ethinylestradiol using diazonium salt grafting onto silver nanoparticles-silica-graphene oxide hybrids.
abstract: This work describes the preparation of an electrochemical immunosensor for ethinylestradiol (EE2) based on grafting of diazonium salt of 4-aminobenzoic acid onto a glassy carbon electrode modified with silver nanoparticles/SiO2/graphene oxide hybrid followed by covalent binding of anti-ethinylestradiol (anti-EE2) to activated carboxyl groups. A competitive immunoassay was developed for the determination of the hormone using peroxidase-labeled ethinylestradiol (HRP-EE2) and measurement of the amperometric response at -200mV in the presence of hydroquinone (HQ) as redox mediator. The calibration curve for EE2 exhibited a linear range between 0.1 and 50ng/mL (r(2)=0.996), with a detection limit of 65pg/mL. Interference studies with other hormones related with EE2 revealed the practical specificity of the developed method for the analyte. A good reproducibility, with RSD=4.5% (n=10) was also observed. The operating stability of a single bioelectrode modified with anti-EE2 was maintained at least for 15 days when it was stored at 4°C under humid conditions between measurements. The developed immunosensor was applied to the analysis of spiked urine with good results.
authors.affiliation: Institute of Chemistry, State University of São Paulo, São Carlos, Brazil.
authors.forename: Fernando H
authors.initials: FH
authors.lastname: Cincotto
authors.affiliation: Department of Analytical Chemistry, Faculty of Chemistry, University Complutense of Madrid, Madrid, Spain.
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Martínez-García
authors.affiliation: Department of Analytical Chemistry, Faculty of Chemistry, University Complutense of Madrid, Madrid, Spain.
authors.forename: Paloma
authors.initials: P
authors.lastname: Yáñez-Sedeño
authors.affiliation: Engineering School, Mackenzie Presbiterian University, São Paulo, Brazil.
authors.forename: Thiago C
authors.initials: TC
authors.lastname: Canevari
authors.affiliation: Institute of Chemistry, State University of São Paulo, São Carlos, Brazil.
authors.forename: S A S
authors.initials: SA
authors.lastname: Machado
authors.affiliation: Department of Analytical Chemistry, Faculty of Chemistry, University Complutense of Madrid, Madrid, Spain.
authors.forename: José M
authors.initials: JM
authors.lastname: Pingarrón
mesh_terms: D055910:Antibodies, Immobilized / Q000276:immunology; D015374:Biosensing Techniques / Q000379:methods*; D003979:Diazonium Compounds / Q000737:chemistry*; D004563:Electrochemistry; D004566:Electrodes; D004997:Ethinyl Estradiol / Q000032:analysis* / Q000737:chemistry / Q000276:immunology / Q000652:urine; D006108:Graphite / Q000737:chemistry*; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry; D006873:Hydroquinones / Q000737:chemistry; D007118:Immunoassay / Q000379:methods*; D057230:Limit of Detection; D053768:Metal Nanoparticles / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*
chemical_list: D055910:Antibodies, Immobilized; D003979:Diazonium Compounds; D006873:Hydroquinones; D012834:Silver; D004997:Ethinyl Estradiol; D012822:Silicon Dioxide; D006108:Graphite; D006861:Hydrogen Peroxide; C031927:hydroquinone
keywords: EE2; Electrochemical immunosensor; Ethinylestradiol; Graphene oxide; Silver nanoparticles; Urine