title: Electrochemical aptasensor for endocrine disrupting 17β-estradiol based on a poly(3,4-ethylenedioxylthiopene)-gold nanocomposite platform.
abstract: A simple and highly sensitive electrochemical DNA aptasensor with high affinity for endocrine disrupting 17β-estradiol, was developed. Poly(3,4-ethylenedioxylthiophene) (PEDOT) doped with gold nanoparticles (AuNPs) was electrochemically synthesized and employed for the immobilization of biotinylated aptamer towards the detection of the target. The diffusion coefficient of the nanocomposite was 6.50 × 10(-7) cm(2) s(-1), which showed that the nanocomposite was highly conducting. Electrochemical impedance investigation also revealed the catalytic properties of the nanocomposite with an exchange current value of 2.16 × 10(-4) A, compared to 2.14 × 10(-5) A obtained for the bare electrode. Streptavidin was covalently attached to the platform using carbodiimide chemistry and the aptamer immobilized via streptavidin-biotin interaction. The electrochemical signal generated from the aptamer-target molecule interaction was monitored electrochemically using cyclic voltammetry and square wave voltammetry in the presence of [Fe(CN)(6)](-3/-4) as a redox probe. The signal observed shows a current decrease due to interference of the bound 17β-estradiol. The current drop was proportional to the concentration of 17β-estradiol. The PEDOT/AuNP platform exhibited high electroactivity, with increased peak current. The platform was found suitable for the immobilization of the DNAaptamer. The aptasensor was able to distinguish 17β-estradiol from structurally similar endocrine disrupting chemicals denoting its specificity to 17β-estradiol. The detectable concentration range of the 17β-estradiol was 0.1 nM-100 nM, with a detection limit of 0.02 nM.
authors.affiliation: Sensor Lab, Department of Chemistry, University of the Western Cape, Bellville 7535, South Africa. rolowu@uwc.ac.za
authors.forename: Rasaq A
authors.initials: RA
authors.lastname: Olowu
authors.forename: Omotayo
authors.initials: O
authors.lastname: Arotiba
authors.forename: Stephen N
authors.initials: SN
authors.lastname: Mailu
authors.forename: Tesfaye T
authors.initials: TT
authors.lastname: Waryo
authors.forename: Priscilla
authors.initials: P
authors.lastname: Baker
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Iwuoha
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000737:chemistry*; D004563:Electrochemistry / Q000379:methods*; D004958:Estradiol / Q000032:analysis*; D053768:Metal Nanoparticles / Q000737:chemistry*; D053761:Nanocomposites / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*
chemical_list: D019086:Bridged Bicyclo Compounds, Heterocyclic; D011108:Polymers; C121383:poly(3,4-ethylene dioxythiophene); D004958:Estradiol