An
effective dual-mode microfluidic paper-based analysis device
(μPAD) was proposed via Bi2S3@MoS2 nanoflowers combined with octahedral CeO2 for
ultrasensitive miRNA-141 bioassay. To obtain the amplified electrochemical
signal, Bi2S3@MoS2 nanoflowers were
first in situ grown onto the surface of cellulose fibers to promote
the reduction of H2O2. The prism-anchored octahedral
CeO2 nanoparticles with a great catalytic function on the
reduction of H2O2 were linked up to the functionalized
cellulose fibers through the hybridization chain reaction to further
enhance the electrochemical signal. By means of the catalysis effect
of Bi2S3@MoS2 nanoflowers and octahedral
CeO2 nanoparticles, the obtained signal was amplified,
thereby achieving ultrasensitive electrochemical detection of the
target. With the help of duplex specific nuclease, the octahedral
CeO2 could be released from the electrochemical detection
area and flow to the color channel through capillary action, which
could initiate the oxidation reaction of 3,3′,5,5′-tetramethylbenzidine
in the existence of H2O2 to generate a blue
visual band, avoiding the error of distinguishing color depth caused
by the naked eye and thus improving the accuracy of the visual method.
Under the optimal conditions, satisfactory prediction and accurate
detection performance were achieved in the range of 10 fM–1
nM and 0.5 fM–1 nM, respectively, by measuring the length of
the blue product and the electrochemical signal intensity. The electrochemical/visual
detection limits of the proposed μPAD for miRNA-141 were as
low as 0.12 and 2.65 fM (S/N = 3). This work provides great potential
for the construction of low-cost and high-performance dual-mode biosensors
for the detection of biomarkers.