Spectroelectrochemical Dynamics of Dendritic Poly (Propylene imine)- Polythiophene Star Copolymer Aptameric 1713-Estradiol Biosensor
Date
2011Author
Iwuoha', Emmanuel
Baker, Priscilla
Njomo, Njagi
Ikpo, Chinwe O.
Baleg, Abd Almonam
Ndangili, Peter M
Olowu, Rasaq A.
Type
ArticleLanguage
enMetadata
Show full item recordAbstract
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 B-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 B-estradiol.
Citation
Int. .J Electrochem. Sci., 6 (2011) 1686 - 1708Publisher
Department of Chemistry, University of the Western Cape, Bellville,