Gold-linked electrochemical immunoassay on single-walled carbon nanotube for highly sensitive detection of human chorionic gonadotropin hormone
A new sensitive gold-linked electrochemical immunoassay (GLEIA) for the detection of the pregnancy
marker human chorionic gonadotropin (hCG) has been developed using the direct electrochemical
detection of Au nanoparticles. We utilized single-walled carbon nanotube (SWCNT) microelectrodes; 24
SWCNT microelectrodes were arrayed on a single Si substrate 25 30 mm
2
in size, for the development
of a new GLEIA (SWCNT-GLEIA). This SWCNT-GLEIA provided convenient and cost-effective tests with
the required antibody and antigen sample volumes as small as 2.0mL for a group of 4 SWCNT
microelectrodes. In addition, this assay also exhibited properties of high sensitivity and selectivity
benefitting from the intrinsic extraordinary features of SWCNTs. Using scanning electron microscopy,
we also observed Au nanoparticle-labeled antigen–antibody complexes immobilized on the surface of
the SWCNT microelectrodes. The concentration of the pregnancy marker (hCG) showed a linear
relationship with the current intensity obtained from differential pulse voltammetry measurements
with a limit of detection (LOD) of 2.4 pg/mL (0.024 mIU/mL) hCG. This LOD is 15 times more sensitive
than a previous GLEIA, which used screen-printed carbon electrodes.
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