A sensitive “turn-off-on” fluorescence platform for bilirubin detection based on conjugated polymer nanoparticles and ferric ions

Abstract

Bilirubin is an important biomarker of jaundice, and the quantitative detection of bilirubin is of great significance in the diagnosis and prevention of early jaundice. In this paper, Fe³⁺ quenched conjugated polymer nanoparticles were used as a "turn-off-on" fluorescence platform to detect bilirubin for the first time. The CPNs_PBMC-COOH were prepared through a nanoprecipitation method based on polystyrene maleic anhydride and PBMC, a conjugated polymer synthesized by our research group. The fluorescence of CPNs_PBMC-COOH can be efficiently quenched closely to 95% by Fe³⁺. The optimized fluorescence platform was obtained (CPNs_PBMC-COOH: 10 μg/mL, Fe³⁺: 4.5 μM). The platform to detect bilirubin has a higher sensitivity with a 5 nM of LOD. The detection range was in the 1.32–26.68 μM, which can cover the concentration of bilirubin in normal adult serum (<25 μM). Moreover, the stoichiometries and binding constants of CPNs_PBMC-COOH, bilirubin, and Fe³⁺ are obtained. The binding ability is better for bilirubin and Fe³⁺. The static quenching mode is found by the absorption spectra and the fluorescence lifetimes. Lastly, this method has obtained satisfactory results in real biological samples (mouse serum and mouse plasma). This work can be used for daily rapid clinical bilirubin detection.

Graphical Abstract

Keywords:

• Fluorescence platform
• detection
• conjugated polymer nanoparticles
• bilirubin
• CPNs_PBMC-COOH

Additional information

Funding

This research was funded by Universities Twenty Foundational Items of Jinan City [Grant No. 2021GXRC097, No. 202228053], the National Natural Science Foundation of China [Grant No. NSFC 51403111] and Shandong Provincial Natural Science Foundation [Grant No. ZR2020MB062]. The Project Supported by the Open Funds from Guangdong Provincial Key Laboratory of Applied Botany [Grant No. AB202105] and the Joint Research Foundation [Grant No. 2019BSHZ0013] for Young Doctorates of Qilu University of Technology (Shandong Academy of Sciences).