Selective and sensitive detection of bilirubin by Fe3+-mediated porphyrin red fluorescence "on-off-on" sensing platform

Bilirubin (BR) serves as a crucial clinical marker for jaundice and liver dysfunction, making its quantitative detection amidst numerous biomolecular interferences of paramount importance. In this work, 5, 10, 15, 20-tetrakis(4-methoxycarbonylphenyl)porphyrin (TPPCOOMe) was utilized as the fluorophore, and Fe3+ was used as the mediator to achieve quantitative detection of BR in human serum through the "on-off-on" fluorescence signal change. The non-fluorescent metalloporphyrin complex TPPCOOMe@Fe3+ generated by the interaction between Fe3+ and TPPCOOMe served as the fluorescence sensing platform. With the addition of BR, the good binding ability between BR and Fe3+ released TPPCOOMe into the sensing medium and restored red fluorescence, while creating conditions for the redox reaction between BR and Fe3+. The fluorescence probe exhibited a good linear relationship with BR in the concentration range of 0–8 μM, the detection limit was as low as 14 nM and the response time was 2 min. Furthermore, a test paper strip-based sensor coupled with a smartphone color-read App was employed to test the fluorescence color changes of TPPCOOMe@Fe3+ for BR sensing, and this intelligent sensing platform had been successfully achieved for the actual detection of BR in human serum without the influence of other metal ions and important biomolecules. [Display omitted] •A near-infrared molecule (TPPCOOMe) based on Fe3+ mediation for detecting bilirubin was reported.•Rapid and sensitive detection of bilirubin was achieved based on an "on-off-on" fluorescent signal response.•A portable smartphone system with test strips had been applied to detect bilirubin in real samples.