Fluorescent carbon dots for highly sensitive bilirubin sensing with excellent selectivity

Abstract

We reported the fluorescence sensor of carbon dots (CDs) synthesized for the highly sensitive and selective detection of bilirubin in human urine. High-resolution transmission electron microscopy (HRTEM) images showed that the CDs have a spherical shape with a mean particle size of 2.6 nm. The CDs showed the fluorescent emission, which peaked at the wavelength of 511 nm under the excitation wavelength of 435 nm. The CDs’ emission intensity reduced with increasing the bilirubin concentration, which was ascribed to the strong inner filter effect (IFE). The excellent spectral match between the bilirubin absorbance and the CDs excitation allowed the fluorescence sensor to be markedly specific only to the presence of bilirubin, permitting the identification of bilirubin even in the presence of other potentially interfering elements. The fluorescence sensor displayed a good linear response to the bilirubin concentration in the wide range of 3.5–45.5 μM with a limit of detection (LOD) of 34 nM, being the remarkably low level even though CDs were synthesized in a facile way without doping. Moreover, this sensing strategy permitted us to quantify bilirubin in the clinical (real) specimen with a good recovery of 95.3–96.8%, indicating a great potential candidate for a cost-effective bilirubin sensing platform in a biomedical application.

Keywords

• Bilirubin
• Biosensor
• Carbon dots
• Facile synthesis
• Fluorescence quenching
• Inner filter effect