Ultrafine palladium based nanozyme exhibiting photothermal and chemodynamic responses with O2 bubble driven motion and glutathione depletion ability

Abstract

For the first time, ultrafine Pd nanoparticles (Pd NPs), 8.7 nm in size, were synthesized using the ‘universal viscosity-mediated assembly strategy’ (UVMAS). An aqueous dispersion containing ultrafine, well-dispersed nanoparticles with a mode hydrodynamic size of 10.1 nm was obtained without any significant agglomeration. Pd NPs synthesized with UVMAS contained Pd (0) (57.2 %) and PdO (42.8 %) phases. A self-propelled motion of Pd NPs was observed, attributed to the generation of O₂ bubbles through the decomposition of H₂O₂ by their strong catalase (CAT)-like activity. Pd NPs also exhibited peroxidase (POD)-like activity. Toxic hydroxyl (●OH) and superoxide anion (O₂^−●) radical generation with Pd NPs was demonstrated by ESR spectroscopy. Their glutathione (GSH) depletion ability was explained by chemisorption of GSH onto Pd NPs via thiol functionality. Pd NPs also exhibited an excellent NIR light absorption, which in turn a photothermal conversion ability with a photothermal conversion efficiency of 43.2 % and a band gap energy of 1.5 eV. The usability of Pd NPs as a promising nanozyme with photothermal and chemodynamic functions was exemplified by the interaction with T98G glioblastoma cells under in-vitro conditions. In-vitro cell deaths up to 85 % were achieved by simultaneous use of photothermal and chemodynamic modalities.