Ultrasensitive
and ultraselective detection of the gene requires
emergency development to meet the medical demands and infectious disease
control. Herein we report a versatile and scalable method based on
electrochemical-chemical-cyclic amplification (EC-CA) and fluorescence
detection for ultrasensitive gene sensing. The EC-CA is achieved by
an electro-Fenton reaction (EFR). The hydroxyl radicals generated
at EFR are trapped by terephthalic acid to form highly fluorescent
2-hydroxyterephthalic acid, which can be sensitively detected by a
fluorescence spectrophotometer. The method is the first to be able
to amplify the signal and reduce the noise simultaneously by using
the conventional analytical methods directly. This described method
can be used for reliable Fe3+ quantification in the range
from 0.1 nM to 0.08 mM. The calculated limit of detection (LOD) is
0.02 nM. Then, hepatitis B virus (HBV) and p53 gene were detected
by this proposed method through introducing the Fe3O4 nanoparticles into the gene hybridization system. The LODs
for HBV and p53 gene even topped out at 2.6 pM and 1.7 fM, respectively.
We demonstrated that the finally recorded signal was triply amplified
through the EC cycle, Fe3O4 nanoparticles, and
sensitive fluorescence detection. At the same time, the background
signal arisen from matrix effects and readout noise was effectively
suppressed. This method shows it is simple, convenient, and operational
through the detection of Fe3+, HBV, and the p53 gene in
blood samples, respectively. We believe our method will make a significant,
near-term impact on the development of high-sensitivity methods that
are versatile and scalable.