Easy diagnosis of jaundice: A smartphone-based sensing bioplatform using carbon dots embedded in bacterial nanopaper for Point-of-Care hyperbilirubinemia diagnosis

Nearly 386,000 babies have been born every day all over the world and about 60 percent of them getting jaundice within the several days of birth. Neonatal jaundice, is a condition that the skin has got a yellow tint and the whites of eyes are turned yellow, due to the accumulation of excess Bilirubin (BL) in blood1. Herein we report a green, low cost and disposable microfluidic nanopaper-based sensor or “lab-on-nanopaper” device for visual determination of BL in human serum samples that monitors Hyperbilirubinemia. Modified bacterial cellulose (BC) nanopapers can be utilized as novel sensing platforms, due to their excellent stability, sustainability and optical transparency2,3. The highly photoluminescence (PL) carbon dots (CDs) embedded on BC nanopapers were used as sensing elements. In the presence of BL, quenching of CDs that were excited by an UV-LED (λ=365 nm), happened4. When BL was exposed to blue light (λ=470 nm) a natural photoisomerization happened, therefore the unconjugated BL converted to the conjugated form5 and the PL of CDs increased. The changes of CDs PL intensity during photoisomerization were used as signal, which can be monitored visually by smartphone camera or fluorometer. The changes were linearly proportional to the concentration of BL in the range of 3-18 mg dL-1. The developed sensor was also used for the determination of BL in human blood serum samples with satisfying results. Building upon the use of BC nanopaper as a new platform with unique properties, we believe the lab on nanopaper devices could be considered as a new generation of optical sensors for analysis of (bio)chemical samples.