In
this work, a novel ratio electrochemical biosensing platform
based on catalytic hairpin assembly target recovery to trigger dual-signal
output was developed for ultrasensitive detection of microRNA (miRNA).
To achieve the ratiometric dual-signal strategy, methylene blue (MB),
an electrochemical indicator, was ingeniously loaded into the pores
of graphene aerogel (GA) and metal–organic framework (MOF)
composites with high porosity and large specific surface area, and
another electrochemical indicator Fe-MOFs with distinct separation
of redox potential was selected as a signal probe. Concretely, with
the presence of the target miRNA, the CHA process was initiated and
the signal probe was introduced to the electrode surface, producing
abundant double-stranded H1-H2@Fe-MOFs-NH2. Then, the measurement
and analysis of the prepared ratiometric electrochemical biosensor
by differential pulse voltammetry (DPV) showed that the introduction
of the target miRNA led to an increase in the oxidation peak signal
of Fe-MOFs (+0.8 V) and a decrease in the oxidation peak signal of
MB (−0.23 V). Therefore, the peak current ratio of I
Fe‑MOFs/I
MB could be employed to accurately reflect the actual concentration
of miRNA. Under optimal conditions, the detection limit of the proposed
biosensor was down to 50 aM. It was worth noting that the proposed
biosensor exhibited excellent detection performance in a complex serum
environment and tumor cell lysates, showing great potential in biosensing
and clinical diagnosis.
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