Femtosecond Spectroscopy of Au Hot-Electron Injection into TiO<sub>2</sub>: Evidence for Au/TiO<sub>2</sub> Plasmon Photocatalysis by Bactericidal Au Ions and Related Phenomena
Marina Radzig,
Olga Koksharova,
Inessa Khmel,
Vladimir Ivanov,
Khursand Yorov,
John Kiwi,
Sami Rtimi,
Elina Tastekova,
Arseny Aybush,
Victor Nadtochenko
Affiliations
Marina Radzig
Institute of Molecular Genetics, Russian Academy of Sciences, Kurchatov Sq. 2, 123182 Moscow, Russia
Olga Koksharova
Institute of Molecular Genetics, Russian Academy of Sciences, Kurchatov Sq. 2, 123182 Moscow, Russia
Inessa Khmel
Institute of Molecular Genetics, Russian Academy of Sciences, Kurchatov Sq. 2, 123182 Moscow, Russia
Vladimir Ivanov
Kurnakov Institute of General and Inorganic Chemistry of the Russian Academy of Sciences, Leninskiy Av 31, 119991 Moscow, Russia
Khursand Yorov
A. N. Belozersky Institute of Physico Chemical Biology and Chemical Department of Lomonosov Moscow State University, 119992 Moscow, Russia
John Kiwi
Ecole Polytechnique Fédérale de Lausanne, EPFL-SB-ISIC-GPAO, Station 6, CH-1015 Lausanne, Switzerland
Sami Rtimi
Ecole Polytechnique Fédérale de Lausanne, EPFL-SB-ISIC-GPAO, Station 6, CH-1015 Lausanne, Switzerland
Elina Tastekova
N. N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, Kosigin str. 4, 119991 Moscow, Russia
Arseny Aybush
N. N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, Kosigin str. 4, 119991 Moscow, Russia
Victor Nadtochenko
A. N. Belozersky Institute of Physico Chemical Biology and Chemical Department of Lomonosov Moscow State University, 119992 Moscow, Russia
In the present work, we provide evidence for visible light irradiation of the Au/TiO2 nanoparticles’ surface plasmon resonance band (SPR) leading to electron injection from the Au nanoparticles to the conduction band of TiO2. The Au/TiO2 SPR band is shown to greatly enhance the light absorption of TiO2 in the visible region. Evidence is presented for the light absorption by the Au/TiO2 plasmon bands leading to the dissolution of Au nanoparticles. This dissolution occurs concomitantly with the injection of the hot electrons generated by the Au plasmon into the conduction band of TiO2. The electron injection from the Au nanoparticles into TiO2 was followed by femtosecond spectroscopy. The formation of Au ions was further confirmed by the spectral shift of the transient absorption spectra of Au/TiO2. The spectral changes of the SPR band of Au/TiO2 nanoparticles induced by visible light were detected by spectrophotometer, and the morphological transformation of Au/TiO2 was revealed by electron microscopy techniques as well. Subsequently, the fate of the Au ions was sorted out during the growth and biofilm formation for some selected Gram-negative bacteria. This study compares the bactericidal mechanism of Au ions and Ag ions, which were found to be substantially different depending on the selected cell used as a probe.
