The abnormally high level of bilirubin (BR) in biofluids
(human
serum and urine) indicates a high probability of jaundice and liver
dysfunction. However, quantification of BR as the Jaundice biomarker
is difficult due to the interference of various biomolecules in serum
and urine. To address this issue, we developed a fluorescence-based
detection strategy, for which yellow emissive carbon dots (YCDs) were
produced from a one-step solvothermal process using phloroglucinol
and thionin acetate as chemical precursors. The as-fabricated YCDs
exhibited a strong fluorescence peak at the wavelength of 542 nm upon
excitation at 390 nm. We used YCDs for detecting BR through the fluorescence
turn-off mechanism, unveiling the excellent sensitivity in the linear
range of 0.5–12.5 μM with a limit of detection (LOD)
of 9.62 nM, which was far below the clinically relevant range. The
analytical nanoprobe also offered excellent detection specificity
for quantifying BR in real samples. Moreover, the biocompatible fluorescent
nanoprobe was successfully employed to target mitochondria in live
cancer cells. A colocalization study confirmed that YCDs possessed
the ability to target mitochondria and overlapped completely with
MitoTracker Red. The developed nanoprobe of YCDs turned out to be
straightforward in their synthesis, noninvasive, and can be utilized
for biomedical sensors to diagnose the onset of jaundice as well as
for mitochondria targeting.