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Impedimetric Aptasensors Based on Carbon Nanotubes – Poly(methylene blue) Composite
Author(s) -
Porfireva Anna V.,
Evtugyn Gennady A.,
Ivanov Alexey N.,
Hianik Tibor
Publication year - 2010
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.201000174
Subject(s) - aptamer , dielectric spectroscopy , methylene blue , carbon nanotube , detection limit , materials science , capacitance , electrochemistry , electrode , redox , chemical engineering , nanotechnology , chemistry , organic chemistry , chromatography , genetics , photocatalysis , engineering , metallurgy , biology , catalysis
The effect of aptamer structure and immobilization platform on the efficiency of thrombin binding and its detection using electrochemical impedance spectroscopy (EIS) characteristics was investigated with aptasensors based on glassy carbon electrodes covered with multiwalled carbon nanotubes (MWNTs). Aptamers with one or two binding sequences GGTTGGTGTGGTTGG specific for thrombin and poly(dA) and poly(dT) tags able to form dimeric products (aptabodies) were used to establish significance of steric and electrostatic factors in aptasensor performance. We have shown that electropolymerization of methylene blue onto MWNTs significantly improved electrochemical characteristics and sensitivity of thrombin detection against bare MWNTs. Charge transfer resistance and capacitance of the surface layer were measured in the presence of redox probe [Fe(CN) 6 ] 3−/4− . Aptasensors make it possible to detect thrombin in the concentration range 1 nM–1 µM with the limit of detection of 0.7 nM (monitoring resistance changes) and 0.5 nM (capacitance changes), respectively.