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

Area of Science:

• Biomedical Engineering
• Materials Science
• Analytical Chemistry

Background:

• Bilirubin (BR) is a heme protein byproduct of hemoglobin breakdown in aged red blood cells.
• Abnormal bilirubin concentrations are linked to various health conditions, including hyperbilirubinemia and coronary disease.

Purpose of the Study:

• To synthesize a cost-effective, highly sensitive, and selective fluorescent sensing platform for bilirubin detection.
• To utilize nitrogen doped carbon dots (NCDs) as the core component of the sensing platform.

Main Methods:

• Nitrogen doped carbon dots (NCDs) were synthesized from citric acid and urea using microwave-assisted synthesis.
• Fluorescence quenching was employed for direct, turn-off detection of bilirubin at specific excitation and emission wavelengths (360 nm and 444 nm, respectively).
• Characterization involved UV-Visible absorption, photoluminescence, SEM, TEM, ATR-FTIR, XPS, and DLS analysis.

Main Results:

• The NCDs demonstrated a sensitive turn-off fluorescence response to bilirubin.
• The sensor achieved a low Limit of Detection (LoD) of 0.32 µM and Limit of Quantification (LoQ) of 1.08 µM for bilirubin.
• The NCD probe exhibited excellent selectivity and sensitivity, even in the presence of interfering biomolecules and ions.

Conclusions:

• The developed fluorescent NCDs provide a selective, sensitive, and low-cost platform for bilirubin detection.
• The sensor's practical feasibility was confirmed through paper-strip-based sensing and analysis of real human samples.