Ultrapure laser-synthesized Si nanoparticles with variable oxidation states for biomedical applications

Area of Science:

• Nanotechnology
• Materials Science
• Biomedical Engineering

Background:

• Chemically synthesized nanoparticles often contain impurities, limiting their biomedical applications.
• Developing high-purity nanoparticles with controlled properties is crucial for advanced nanomedicine.

Purpose of the Study:

• To fabricate ultrapure silicon-based nanoparticles (Si-NPs) using femtosecond laser fragmentation.
• To characterize the synthesized Si-NPs and evaluate their potential for biomedical applications.

Main Methods:

• Femtosecond laser fragmentation of water-dispersed microcolloids to produce Si-NPs.
• Z-potential measurements for colloidal stability assessment.
• Structural analysis (including oxide content) and dissolution tests.
• In vitro cell interaction studies (cytotoxicity and internalization) with human cells.

Main Results:

• Spherical Si-NPs with controlled size (few nm to tens of nm) and negative surface charge (-35 mV) were fabricated.
• Si-NPs consist of Si nanocrystals with a SiOₓ shell; oxide content varies with oxygen exposure during synthesis.
• All Si-NPs exhibited good water-solubility, with more oxidized NPs dissolving faster.
• No adverse effects were observed in human cells up to 50 μg mL⁻¹, and good internalization via endocytosis was confirmed.

Conclusions:

• Laser-synthesized Si-NPs offer superior purity compared to chemically synthesized ones.
• The fabricated Si-NPs demonstrate excellent biocompatibility and cellular uptake.
• These ultrapure Si-NPs are promising for safe and effective nanomedicine applications, including imaging and therapeutics.