22 February 2017 Influence of oxidation state on water solubility of Si nanoparticles prepared by laser ablation in water
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Femtosecond laser fragmentation from preliminarily prepared water-dispersed Si microcolloids was used to synthesize bare (ligand-free) spherical silicon nanoparticles (Si-NPs) with low size dispersion and controllable mean size from a few nm to several tens of nm. In order to control the oxidation state of Si-NPs, the fragmentation was performed in normal oxygen-saturated water (oxygen-rich conditions) or in water disoxygenated by pumping with noble gases (Ag, He) before and during the experiment (oxygen-free conditions). XPS and TEM studies revealed that Si-NPs were composed of Si nanocrystals with inclusions of silicon oxide species, covered by SiOx (1 < x < 2) shell, while the total oxide content depended whether Si-NPs were prepared in oxygen-rich or oxygen-free conditions. When placed into a dialysis box, waterdispersed Si-NPs rapidly dissolved, which was evidenced by TEM data. In this case, NPs prepared under oxygen-rich conditions demonstrated much faster dissolution kinetics and their complete disappearance after 7-10 days, while the dissolution process of less oxidized counterparts could last much longer (25-30 days). Much fast dissolution kinetics of more oxidized Si-NPs was attributed to more friable structure of nanoparticle core due to the presence of numerous oxidation-induced defects. Laser-synthesized Si-NPs are of paramount importance for biomedical applications.
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Yu. V. Ryabchikov, Yu. V. Ryabchikov, A. Al-Kattan, A. Al-Kattan, V. Chirvony, V. Chirvony, J. F. Sanchez-Royo, J. F. Sanchez-Royo, M. Sentis, M. Sentis, V. Yu. Timoshenko, V. Yu. Timoshenko, A. V. Kabashin, A. V. Kabashin, } "Influence of oxidation state on water solubility of Si nanoparticles prepared by laser ablation in water", Proc. SPIE 10078, Colloidal Nanoparticles for Biomedical Applications XII, 100780C (22 February 2017); doi: 10.1117/12.2257404; https://doi.org/10.1117/12.2257404

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