Cysteine-induced hormesis effect of silver nanoparticles

Area of Science:

• Nanotechnology
• Toxicology
• Microbiology

Background:

• Silver nanoparticles (AgNPs) toxicity is well-documented.
• The hormesis effect of AgNPs, particularly at low concentrations, remains under-explored.
• Understanding hormesis is crucial for applications involving nanomaterials.

Purpose of the Study:

• To investigate the hormesis effect of silver nanoparticles (AgNPs) at low concentrations.
• To explore the role of cysteine in modulating AgNP-induced hormesis.
• To determine the concentration-dependent relationship between cysteine, AgNPs, and cellular response.

Main Methods:

• Exposure of bacterial cultures to varying concentrations of AgNPs.
• Administration of cysteine at different concentrations alongside AgNPs.
• Quantification of bacterial viability and sulfuration rates (n_s/n_Ag).

Main Results:

• A significant hormesis effect was observed at low AgNP concentrations (0.34 mg L^-1), increasing bacterial viability by 29.9%.
• Cysteine induced a hormesis effect within AgNP concentrations of 1.7–5.1 mg L^-1 at a cysteine concentration of 12.5 mg L^-1.
• The cysteine-induced hormesis effect demonstrated a concentration-dependent relationship, with a sulfuration rate (n_s/n_Ag) of 6.15 showing strong cellular excitation.

Conclusions:

• Low concentrations of AgNPs can exert a beneficial hormesis effect on bacterial viability.
• Cysteine can modulate AgNP toxicity, inducing hormesis in a concentration-dependent manner.
• The sulfuration rate is a key factor in the cysteine-mediated hormesis of AgNPs, highlighting potential mechanisms for nanoparticle-cell interactions.