Dual-mode fluorescence and colorimetric detection of bilirubin using a curcumin-methylene blue metal-organic framework composite.

Neonatal jaundice requires rapid and reliable bilirubin monitoring to prevent severe complications. Here, a dual-mode (fluorescence-colorimetric) sensing platform is developed by encapsulation of curcumin within an amine-functionalized zirconium metal-organic framework (UiO-66-NH₂) in the presence of methylene blue. The MOF scaffold provides aqueous stability and adsorption sites for bilirubin, while curcumin serves as the fluorescence reporter and methylene blue enables complementary optical modulation. Bilirubin induces concentration-dependent fluorescence quenching. The sensor exhibits reproducible behavior with multiple linear regions in buffer solution. In diluted human serum, a linear calibration response was obtained over 25-130 nM with a limit of detection of 8.14 nM, and acceptable spike recoveries of 97-104% were obtained over the validated 55-95 nM recovery range. High selectivity is observed against common salts, biomolecules, and proteins tested at large excess. This dual-readout MOF-based system provides a robust strategy for bilirubin analysis in serum and establishes a practical framework for future extension toward minimally-invasive bilirubin monitoring in clinical settings.