Levonorgestrel-protected Au₈ and Au₁₀ clusters with different antimicrobial abilities

Area of Science:

• Nanotechnology
• Biochemistry
• Materials Science

Background:

• Gold nanoclusters (AuNCs) show potential for antimicrobial applications due to stability and biocompatibility.
• Lack of atomic-precise structures in previous AuNCs hinders understanding of structure-property relationships.
• Antibacterial efficacy is often linked to AuNC size and composition.

Purpose of the Study:

• To synthesize and characterize structurally defined gold-levonorgestrel nanoclusters (Au8NCs and Au10NCs).
• To investigate the antibacterial activity of Au8NCs and Au10NCs.
• To elucidate the structure-activity relationship in AuNC-based antimicrobial agents.

Main Methods:

• Synthesis of atomically precise gold-levonorgestrel clusters (Au8NCs and Au10NCs).
• Evaluation of antibacterial activity against bacterial strains.
• Analysis of bacterial cell wall/membrane damage and intracellular component leakage.
• Assessment of glutathione reductase inhibition in bacteria.

Main Results:

• Au8NCs exhibited stronger antibacterial activity compared to Au10NCs.
• Au8NCs caused more significant damage to bacterial cell walls and membranes.
• Au8NCs showed stronger inhibition of bacterial glutathione reductase activity.
• Disruption of intracellular antioxidant balance and enzyme inhibition led to bacterial death.

Conclusions:

• The precise atomic structure of gold nanoclusters significantly influences their biological activity.
• Au8NCs are more effective antibacterial agents due to structural differences impacting bacterial integrity and enzyme function.
• Structural control is crucial for designing next-generation antimicrobial gold nanoclusters.