Nanoparticle-Sensitized Photodegradation of Bilirubin and Potential Therapeutic Application

Bilirubin (BR) is a protective antioxidant; however, when its conjugation and excretion are impaired, as in neonatal and hereditary jaundice, BR accumulates and may cause severe neurotoxicity. Here, we report a novel mechanism for ZnO nanoparticle (NP)-sensitized BR degradation via defect-mediated nonradiative energy transfer pathway. Among different sizes and shapes, ZnO particles with diameter of 5 nm having very high concentration of defect states are found to be the most effective catalyst, which particularly follows a pseudofirst-order kinetics validating the Langmuir-Hinshelwood model of surface catalysis. The nontoxic wide band gap ZnO NPs essentially transmit defect-mediated visible optical radiation, which is not supposed to interfere with the conventional phototherapy process. Therefore, the recyclable ZnO nanocatalysts essentially invite an added advantage in potential therapeutic applications and/or in a flow-device that has been explored in the present study.