Spectroelectrochemical Dynamics of Dendritic Poly (Propylene imine)- Polythiophene Star Copolymer Aptameric 1713-Estradiol Biosensor
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Date
2011-02-20
Authors
Ndangili, Peter M
Olowu, Rasaq A.
Baleg, Abd Almonam
Ikpo, Chinwe 0.
Njomo, Njagi
Baker, Priscilla
Iwuoha, Emmanuel
Journal Title
Journal ISSN
Volume Title
Publisher
International Journal of ELECTROCHEMICAL SCIENCE
Abstract
Aptamers, which are in vitro-selected functional oligonucleotides, have been employed to design novel aptasensor due to their inherent high selectivity and affinity compared to traditional biorecognition elements. This report presents a novel aptamer biosensor for determining the endocrine disrupting compound (EDC), 17~-estradiol (E2), which was constructed from a SELEX-synthesized 76-mer biotinylated aptamer for 17~-estradiol incorporated in a dendritic generation 1 poly(propylene imine)-
poly thiophene (G 1PPT-co-PEDOT) star copolymer-functionalised Au electrode via biotin-avidin interaction. The sensor platform and aptasensor were interrogated with scanning electron microscopy (SEM), FTIR, electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and square wave voltammetry (SWV). The kinetic parameters of the sensor platform were determined by
modelling the [Fe(CN)6r3/ - 4 (redox probe) Nyquist and Bode impedimetric spectra to the appropriate equivalent electrical circuit. The EIS spectra shows that at low frequencies (100 mHz) when the electronics of the electrode systems are only minimally perturb.ed.. the AuIG1PPT-co-PEDOT nanoelectrode exhibited greater semi-conductor behaviour (higher phase angle value) than AulG IPPT due to the incorporation of charged functionalized dendrimer. However, the Bode plot also shows that
the charge transfer dynamics of the nanoelectrode can be frequency modulated. The biosensor response to 17~-estradiol was based on the decrease in the SWV current as the EDC binds to the ssDNA aptamer on the biosensor. The dynamic linear range of the sensor was 0.1 - 100 nM. These initial studies also showed that the aptamer used in this study was very selective to, and reproducible for, 17-~-estradiol.
Description
Keywords
Functionalized dendrimer, conducting polymer, 17~-estradiol (E2),, star copolymer, SELEX,, endocrine disrupting compound, DNA aptamer, electrochemical impedance spectroscopy
Citation
Int. .J Electrochem. Sci., 6 (2011) 1686 - 1708