Yellow Emissive Carbon\nDots – A Robust Nanoprobe\nfor Highly Sensitive Quantification of Jaundice Biomarker and Mitochondria\nTargeting in Cancer Cells

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