Unveiling the Antibacterial Mechanism of Gold Nanoclusters via In Situ Transmission Electron Microscopy

Abstract

Metal nanoclusters (NCs) with unique chemical and physical properties have been extensively demonstrated to be emerging nanoantibiotics for fighting bacterial infections. Understanding the antibacterial mechanisms of metal nanoclusters is important for evaluating their clinical applications as nanoantibiotics. To understand the antibacterial mechanism, gold nanoclusters (AuNCs) were applied as an antibacterial agent for real-time observations of their interactions with bacteria by in situ transmission electron microscopy (TEM). In this work, a surface ligand of glutathione-conjugated (GSH)-AuNCs was prepared via a simple hydrothermal method. Optical and structural characterizations validated the successful preparation of GSH-AuNCs. Bacterial growth curves of Acetobacter aceti revealed that the antibacterial activity of GSH-AuNCs increased with the weight concentration. The antibacterial activity of GSH-AuNCs was confirmed by the intracellular reactive oxygen species (ROS) generation induced by GSH-AuNCs in A. aceti. Furthermore, real-time observations of interactions between GSH-AuNCs and A. aceti were made using in situ liquid cell TEM. Based on the results of real-time observations, GSH-AuNCs first attached onto the bacterial membranes of A. aceti by physical adsorption and then penetrated into A. aceti by internalization. Eventually, the production of intracellular ROS induced by GSH-AuNCs caused destruction of the bacterial membranes, which led to the death of A. aceti. After the bacterial membranes had been destroyed, A. aceti eventually died.

Phase-Dependent 1T/2H-MoS2 Nanosheets for Effective Photothermal Killing of Bacteria

“…Nanomaterials have emerged as viable options in antibacterial investigations, given the growing global threat of antimicrobial resistance. − Organic, metal, and metal oxide nanomaterials have all been recognized as extremely promising antimicrobial materials. − These various nanomaterials exhibit a wide range of intrinsic chemical composition features, which may explain their various mechanisms of action. − The antibacterial efficiencies of these nanomaterials have been linked to their physicochemical properties, such as chemical modifications, shape, size, nanomaterial coating, synthesis solvent, and NP ratio within a nanocomposite. − Furthermore, the crystallographic facet of a nanomaterial has also been identified as a determinant of its antibacterial activity . Although numerous parameters influencing a nanomaterial’s antibacterial activity have been identified, there is still a dearth of detailed knowledge as to how some intrinsic factors of specific nanomaterials affect their antibacterial potency.…”

Inhibition of cancer cells using target-specific 2A3 antibody-conjugated gold nanoclusters

“…AgNCs and CuNCs have been validated the antibacterial activities because of the destruction of the bacterial cell wall and the increase of intracellular ROS generation [28]. Real-time observation has demonstrated the antibacterial mechanism between the surface ligand of glutathione conjugated AuNCs and bacteria by in situ liquid cell transmission electron microscopy (TEM) [29]. Although the intensive achievements studies have proven the antibacterial activity of metal NCs, there are only very few studies to demonstrate the cancer therapy using metal NCs.…”

Calcium Phosphate Nanoclusters for the Repair of Tooth Enamel Erosion

“…Nanomaterials synthesized by metals, semiconductors, and oxides with distinctive chemical and physical characteristics have been extensively explored for applications in biomedicine, energy transformation, and electronics [24][25][26][27][28][29][30][31][32][33][34][35][36][37][38]. In various nanomaterials, nanoclusters (NCs) with sizes ranging from several atoms to a few hundred atoms have garnered great attention because of their superior structural and optical behaviors [39][40][41][42][43][44]. For example, cysteine-conjugated gold NCs were applied for bacterial detection and inhibition due to their unique size and fluorescence [39].…”