Gold nanoparticles have important diagnostic and therapeutic uses. Furthermore, they have recently been found to act as potent antimicrobial agents. Soft X-ray tomography (SXT) was
used alongside light fluorescence and electron microscopy to elucidate the mechanism of gold nanoclusters’ antibacterial action by mapping their distribution and visualizing their
interactions with Gram-negative Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus bacteria.
Observation of the nanoclusters within the bacterial cell linked their toxicity to accumulation in the bacterial cytoplasm rather than incurring damage at the bacterial membrane. SXT strengthened this hypothesis by revealing the formation of hollow non-membrane-bound intracellular vesicles in bacteria as early as 15 minutes after the introduction of the nanoclusters. This microscopy study led the authors to propose that the nanoclusters do not damage the bacterial membrane as they freely transit into the bacterial cell interior. Instead, they cause devastating internal damage to the bacterial cell, most likely by binding to the cytoskeletal network and other proteins necessary for cell function without compromising the nucleoid.
Denver P. Linklater, Xavier Le Guével, Gary Bryant, Vladimir A. Baulin, Eva Pereiro, Palalle G. Tharushi Perera, Jason V. Wandiyanto, Saulius Juodkazis, and Elena P. Ivanova, ACS Appl. Mater. Interfaces 2022, 14,32634-32645
