In situ growth of luminescent d-f MOF nanostructures on bacterial cellulose as an accessible kit for early jaundice diagnosis

During the initial week after birth, a majority of newborns experience hyperbilirubinemia and jaundice as a result of the build-up of unconjugated Bilirubin (BR) in their bloodstream. If elevated BR levels are not adequately addressed, it could result in brain damage. Despite advancements in luminescence-based sensing technology for clinical purposes, there remains a significant demand for diagnostic devices with accurate, specific, portable, and affordable features. We present a luminescent nanopaper-based assay kit for visual recognition of BR. This novel kit comes with a smartphone readout, enabling effortless recognition of BR. To develop the kit, a new d - f heterometallic MOF {[Ce₂Zn(pzdc)₄(H₂O)₆]·2H₂O}_n (pzdc = 2,3-pyrazinedicarboxylic acid) (CeZn-MOF) with advantageous photophysical features was grown on bacterial cellulose (BC) nanofibers to form BC@CeZn-MOF platform. The platform's luminescence quenches in the presence of BR with a turn-off mechanism originating from Inner Filter Energy (IFE). The luminescence quenching was linearly proportional to the concentration of BR in range of 0.1 - 20 mg.dL^{- 1} (LOD = 0.027 mg.dL^{- 1}), and recognition of small amount of BR could be attained with a smartphone camera. Furthermore, the luminescence emission of the sensing platform was recovered upon UV light (470 nm) through photo-isomerizing of BR into lumirubin as a non-PL quencher. The kit's feasibility was confirmed through validating its practicality for detecting BR in human serum samples and its compatibility with clinical procedures. The non-poisonous nature and distinctive photophysical characteristics of platform makes it an excellent choice, easy-to-use BR recognition assay kit.