Construction of mitochondria targeted and FRET based ratiometric sensing nanoplatform for sulfur dioxide accurate detection in vitro and in vivo

Sulfur dioxide (SO 2 ) is a key molecule in organisms that is involved in the regulation of different physiological procedures. Aberrant SO 2 causes a variety of diseases, such as cancer and neurodegeneration. Thus, sensitive and selective detection of SO 2 is of great importance. Based on the Förster resonance energy transfer (FRET) between green fluorescence carbon dots (GCDs) donor and amide-linked near-infrared fluorescence emissive organic small molecular dye (CDDBT) acceptor, one ratiometric fluorescent nano platform, Mito-GCDs-CDDBT for mitochondria SO 2 sensing was constructed. In this FRET sensing system, CDDBT served as the receptor for SO 2 , and the presence of SO 2 enhanced GCDs green fluorescence signal and quenched CDDBT near-infrared fluorescence signal due to the disruption of FRET. Mito-GCDs-CDDBT could sensitively detect SO 2 with a detection limit of as low as 0.701 μM. Meanwhile, Mito-GCDs-CDDBT achieved fluorescence imaging to measure the response of cellular exogenous and endogenous SO 2 with remarkable mitochondrial targeting. Moreover, Mito-GCDs-CDDBT also realized SO 2 sensing in vivo including zebrafish and mice. The as-prepared versatile nanoplatform displayed several advantages, such as mitochondria targeting, FRET-based sensitive detection, and sensing capabilities in biological milieu. Potentially, it could be applied in the diagnostics of SO 2 involved diseases.