Comet-like Heterodimers "Gold Nanoflower @Graphene Quantum Dots" Probe with FRET "Off" to DNA Circuit Signal "On" for Sensing and Imaging MicroRNA In Vitro and In Vivo.

Cardiovascular diseases have recently become the number one cause of death worldwide and the risk of getting cardiovascular diseases is doubled as the age increases. MicroRNA-34a (miRNA-34a) as an important potential sensor of aging and cellular senescence could be used in early diagnostics. Herein, a new ultrasensitive platform on the basis of the fluorescence resonance energy transfer (FRET) "off" to DNA circuit signal "on" principle was established, termed comet-like heterodimers gold nanoflower (AuNF) @ graphene quantum dots (GQDs) probe. We discussed that the distance of 4 nm between AuNF and GQDs would increase fluorescence quenching efficiency, and light up sensitivity after the probe combined with a target miRNA initiating DNA circuit strategy. The target miRNA-34a can be quantified down to 0.1 fM, which is about 2 orders of magnitude lower than the existing sensing protocols. Furthermore, we constructed the aging myocardial cell and animal model, and the nanoprobe presented low cytotoxicity and satisfied signal imaging in vitro and in vivo. Significantly, this platform herein is envisioned to provide a reliable guidance for early diagnosing cardiovascular diseases and proposing therapeutic protocols.