Carbon Nanotube-Polyamidoamine Dendrimer Hybrid-Modified
Electrodes for Highly Sensitive Electrochemical Detection of MicroRNA24
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Abstract
A simple
and ultrasensitive microRNA (miRNA) electrochemical biosensor
employing multiwalled carbon nanotube (MWCNT)-polyamidoamine (PAMAM)
dendrimer and methylene blue (MB) redox indicator is reported in this
work. The assay utilizes a glass carbon (GC) electrode modified with
MWCNT-PAMAM, on which the oligonucleotide capture probes are immobilized.
The electrochemical detection of miRNAs is completed by measuring
the reduction signal change of MB before and after the probe hybridization
with target miRNA (miRNA24 is used as a model case). The MWCNT-PAMAM/GC
electrode shows greatly enhanced signal to MB reduction in contrast
to bare GC electrode. The functionalization of MWCNT with PAMAM maintains
the electrochemical property of MWCNT to MB reduction but minimizes
the undesired adsorption of MB on the MWCNT surface. The effect of
experimental variables on the miRNA detection is investigated and
optimized. A detection limit of 0.5 fM and a linear peak current density-concentration
relationship up to 100 nM are obtained following 60 min hybridization.
The proposed assay is successfully used to detect miRNA24 in total
RNA sample extracted from HeLa cells