Ratiometric fluorescence sensor for point-of-care testing of bilirubin based on tetraphenylethylene functionalized polymer nanoaggregate and rhodamine B

Monitoring of free bilirubin in a point-of-care fashion is urgently needed in particular for newborns and liver dysfunction patients. Herein, a novel hybrid ratiometric fluorescence sensor was designed and fabricated for the rapid, sensitive and selective detection of free bilirubin in water and urine. The sensor was composed of Rhodamine B and polymer nanoaggregate of tetraphenylethylene functionalized hyperbranched polyamido-amine, which exhibited dual emission peaked at 577 nm and 465 nm. The fluorescence peak at 465 nm could be sufficiently suppressed by Fo center dot rster resonance energy transfer between the polymer nanoaggregate and bilirubin, while the peak at 577 nm arising from Rhodamine B was insensitive to bilirubin, which resulted in a visually discernible blue to orange fluorescence color change. The concentrations of bilirubin could be evaluated by the fluorescence intensity ratios and the detection limit was as low as 25 nM. A portable hydrogel-based point-of-care testing device was constructed by integrating the recognition sensor in hydrogel and employed for bilirubin test. This hydrogel-based assay is convenient and affordable, providing a promising tool for at-home bilirubin detection and bilirubin-related disease diagnosis.