Engineering highly effective antimicrobial selenium nanoparticles through control of particle size

Area of Science:

• Nanotechnology
• Materials Science
• Microbiology

Background:

• Antibiotic resistance is a major global health threat, necessitating novel antimicrobial agents.
• Selenium nanoparticles (Se NPs) demonstrate antimicrobial potential against Gram-positive bacteria.
• The impact of Se NP size on antibacterial efficacy remains under-investigated.

Purpose of the Study:

• To systematically investigate the effect of Se NP size on antibacterial activity and mammalian cytotoxicity.
• To identify an optimal Se NP size for maximal antimicrobial efficacy against Staphylococcus aureus.
• To elucidate the size-dependent mechanisms of action of Se NPs.

Main Methods:

• Fabrication of spherical Se NPs with diameters ranging from 43 to 205 nm.
• Systematic evaluation of antibacterial activity against methicillin-sensitive and methicillin-resistant Staphylococcus aureus (MSSA and MRSA).
• Assessment of mammalian cell cytotoxicity and determination of minimum inhibitory concentration (MIC).

Main Results:

• Antibacterial activity of Se NPs is strongly dependent on size, with 81 nm Se NPs exhibiting maximal efficacy.
• Se NPs demonstrated multi-modal mechanisms of action, including ATP depletion, ROS induction, and membrane potential disruption, which varied with size.
• All tested Se NPs showed no toxicity to mammalian cells at concentrations up to 25 μg mL-1.
• The 81 nm Se NPs achieved a significantly lower MIC value (16 ± 7 μg mL-1) compared to previously reported values.

Conclusions:

• Se NP size is a critical, tunable parameter for enhancing antimicrobial efficacy.
• 81 nm Se NPs at a concentration of 10 μg mL-1 represent a promising, safe, and effective strategy for combating Staphylococcus aureus infections.
• This study provides a foundation for the development of size-optimized selenium nanoparticles as a new class of antimicrobial agents.