As a kind of important potential
biomarkers, the expression level of some
microRNAs (
miRNAs) is closely related to
cancer development and progression. Herein, a reusable ultra-sensitive "fuel-loadings" bioluminescent sensor was constructed to detect the trace
miRNA based on the cascading signal amplification, which combined the target-introducing "fuel-loading" mechanism and cyclic bioluminescence assay. In this sensor, magnetic beads labeled with hairpin
DNA probes (hDNA) could specifically hybridize with the target
miRNA and isolate these targets from samples. Then, the target-introducing "fuel loading" mechanism worked because the
poly(A) polymerase can catalyze the template-independent sequential addition of
adenosine monophosphate (
AMP) to the 3' ends of the
miRNA targets to produce long
poly(A) tails. The long
poly(A) tails provided lots of 5'AMPs (cleaved by
Exonuclease T), which further as fuels were converted into
adenosine-triphosphate (
ATP) to generate an enhanced bioluminescent signal by
cyclic AMP pyrophosphorylation-
ATP dephosphorylation. The "fuel-loadings" bioluminescent sensor realized a high sensitivity with a limit-of-detection of about 22.6 aM for
miRNA 21. Moreover, this "fuel-loadings" bioluminescent sensor not only achieved regenerable and reusable measurement in the same microwell to decrease the analysis costs, but also could directly detect
miRNA 21 in the serum without complicated extraction procedures. It showed excellent coherence with quantitative reverse transcription polymerase chain reaction for
miRNA 21 detection of
cancer patients' samples, indicating clinical translation potential for
miRNA detection.