Synthesis and Characterization of 3?4 nm Sized Fe-Containing Silicon Nanoparticles

JUAN J. ROMERO; MARC WEGMANN; HERNÁN B. RODRÍGUEZ; CRISTIAN LILLO; ALDO RUBERT; SABRINA C. GARCIA; STEFANIE KLEIN; CAROLA KRYSCHI; MONICA L. KOTLER; MÓNICA C. GONZALEZ

Córdoba

Congreso; 16th International Congress on Photobiology; 2014

International Union of Photobiology

Silicon nanoparticles of 1?5 nm size (SiNPs) are biocompatible and produce reactive oxygen species upon UV-visible or X-ray excitation, making them potential candidates for photodynamic therapy and radiotherapy of cancer. Moreover, they exhibit photoluminescence and represent an alternative for fluorescence imaging. Combination of SiNPs with magnetic nanomaterials may allow the combination of fluorescence and magnetic resonance imaging. An approach to design bimodal imaging agents of low toxicity consists on iron-doped silicon nanoparticles (Fe-SiNPs) [1]. In the present work, we synthesized Fe-SiNPs from a modified procedure of the iron-doped sodium silicide precursor reported in the literature [1] and investigated the effect of iron on the photoluminescence and singlet oxygen generation, in an attempt to further understand its potential technological uses. Surface-oxidized (SiOx-Fe-SiNPs) and propylaminederivatized nanoparticles (PA-Fe-SiNPs) were characterized by high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy, inductively coupled plasma mass spectrometry, time-resolved and steady-state photoluminescence, and singlet oxygen production upon UV-visible excitation. Cytotoxicity in rat glioma C6 cells (24 hours exposure) was evaluated using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Blue-emitting crystalline nanoparticles of 3-4 nm size were obtained. Emission and singlet oxygen production were substantially quenched on iron incorporation, emission arriving mainly from iron-free nanoparticles. Exposure to 10 µg/ml of SiOx-Fe-SiNPs and PA-Fe-SiNPs resulted in 5% and 15% decrease in cell viability, respectively, while at higher concentrations (100 µg/ml) SiOx-FeSiNPs induced a 65% of cell death, being 85% for PA-Fe-SiNPs.