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. 2025 May;35(5):3565-3576.
doi: 10.1007/s10895-024-03771-0. Epub 2024 Jun 12.

Fluorescent Nitrogen-doped Carbon Dots-based Turn-off Sensor for Bilirubin

Aswathy A O  1 , B A Akhila  1 , Sony George  2
Affiliations

Fluorescent Nitrogen-doped Carbon Dots-based Turn-off Sensor for Bilirubin

Aswathy A O et al. J Fluoresc. 2025 May.

Abstract

Bilirubin (BR), a heme protein produced from breakdown of haemoglobin is present in aged red blood cells; whose abnormal concentration is associated with diseases like hyperbilirubinemia, coronary disease, iron deficiency, and so on. Herein, we have synthesized a selective, sensitive, and low-cost sensing platform using fluorescent nitrogen doped carbon dots (NCDs), prepared from precursors; citric acid and urea via a simple microwave-assisted method. The emission at 444 nm on excitation with 360 nm was well quenched in presence of BR suggesting a direct turn-off detection for BR. Characterization of developed probe was done by UV-Visible absorption studies, photoluminescence studies, SEM, TEM, ATR-FTIR, XPS, and DLS analysis. BR was detected with a Limit of Detection (LoD) and Limit of Quantification (LoQ) of 0.32 µM and 1.08 µM respectively. NCDs exhibited excellent selectivity and sensitivity towards BR in the presence of co-existing biomolecules and ions. Practical feasibility was checked by paper-strip-based sensing of BR and spiked real human samples were used for conducting real sample analysis.

Keywords: Bilirubin; Fluorescence sensing; Hyperbilirubinemia; Inner filter effect; Jaundice.

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Conflict of interest statement

Declarations. Ethical Approval: The experiments were done following the Indian Council of Medical Research (ICMR) ethical standards and were approved by the University level Human Ethical Committee order no (ULECRIHS/UOK/2019/48, University of Kerala, Thiruvananthapuram). All the healthy volunteers who donated the blood samples were provided consent to participate and publish the result. Competing Interests: The authors declare no competing interests. Supporting Information: Additional supporting information can be found online in the supporting information section at the end of this article.

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