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Tumor necrosis factor (TNF) is a key component of the innate immune response. Upon binding to its receptor, TNFR1, it promotes production of other cytokines via a membrane-bound complex 1 or induces cell death via a cytosolic complex 2. To understand how TNF-induced cell death is regulated, we performed mass spectrometry of complex 2 and identified tankyrase-1 as a native component that, upon a death stimulus, mediates complex 2 poly–ADP-ribosylation (PARylation). PARylation promotes recruitment of the E3 ligase RNF146, resulting in proteasomal degradation of complex 2, thereby limiting cell death. Expression of the ADP-ribose–binding/hydrolyzing severe acute respiratory syndrome coronavirus 2 macrodomain sensitizes cells to TNF-induced death via abolishing complex 2 PARylation. This suggests that disruption of ADP-ribosylation during an infection can prime a cell to retaliate with an inflammatory cell death.

This study first investigates the preparation and characterization of titanium dioxide/reduced graphene oxide (TiO2/rGO) and then proposes the fabrication of photoanode in dye-sensitized solar cell (DSSC) from synthesized materials. Herein, the TiO2/rGO nanocomposites were prepared by the incorporation of hydrothermal approach and co-precipitation method from the precursors of titanium (IV) isopropoxide and graphene oxide. The fabrication of photoanode from the as-prepared TiO2/rGO nanocomposite paste was carried out using screen-printing technique. The performance of fabricated DSSCs was evaluated by current density-voltage curves and electrochemical impedance spectroscopy. The characterizations of TiO2 nanoparticles, TiO2/rGO nanocomposites, and their precursors were confirmed by ultraviolet-visible spectroscopy, Fourier-transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction, and transmission electron microscopy. Experimental data showed that the optimal rGO weight percentage of 0.6% in the TiO2/rGO nanocomposite material fabricated DSSC successfully with the highest values of short-circuit current density (17.65 mA/cm2) and energy conversion efficiency (7.46%), approximately increasing 24% and 25%, respectively, in comparison with the pristine TiO2 material. Characterization results indicated that the incorporated hydrothermal co-precipitation method was efficient in producing well-defined spherical TiO2 nanoparticles decorated on the rGO sheets with an average diameter of 20–25 nm. Therefore, the TiO2/rGO nanocomposites with the eco-friendly and efficient synthesis method are highly promising for manufacturing and commercializing DSSCs widely.