Catalytic Hairpin Assembly-Driven Ratiometric Dual-SignalElectrochemical Biosensor for Ultrasensitive Detection of MicroRNABased on the Ratios of Fe-MOFs and MB-GA-UiO-66-NH2

information:in this work, a novel ratio electrochemical biosensing platform based oncatalytic hairpin assembly target recovery to trigger dual-signal output was developed forultrasensitive detection of microRNA (miRNA). To achieve the ratiometric dual-signalstrategy, methylene blue (MB), an electrochemical indicator, was ingeniously loaded intothe pores of graphene aerogel (GA) and metal-organic framework (MOF) composites withhigh 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 probewas introduced to the electrode surface, producing abundant double-stranded H1-H2@Fe-MOFs-NH2. Then, the measurement and analysis of the prepared ratiometric electro-chemical biosensor by differential pulse voltammetry (DPV) showed that the introductionof 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 currentratio ofIFe-MOFs/IMBcould be employed to accurately reflect the actual concentration of miRNA. Under optimal conditions, thedetection limit of the proposed biosensor was down to 50 aM. It was worth noting that the proposed biosensor exhibited excellentdetection performance in a complex serum environment and tumor cell lysates, showing great potential in biosensing and clinicaldiagnosis.