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The genotoxic potential of citrate-stabilized gold nanoparticles, micellar encapsulated iron oxide nanoparticles, and cadmium-based semiconductor quantum dots with different shell compositions was tested using the automated microscope system AKLIDES.

Iron-containing silicon nanoparticles were synthesized in an attempt to understand the effect of iron on the silicon nanoparticle (SiNP) photoluminescence and singletoxygen generation capacity. A wet chemical oxidation procedure of the sodium silicide precursor, obtained from the thermal treatment in anaerobic conditions of a mixture of sodium, silicon, and an iron (III) organic salt under anaerobic conditions, was employed. Surface-oxidized and propylamine-terminated SiNPs were characterized using high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, time-resolved and steady-state photoluminescence, and time-correlated fluorescence anisotropy. Based on differences in the morphology, crystal structure, density, and photoluminescence spectrum, two distinct types of SiNPs were identified in a given synthesis batch: iron-free and iron-containing SiNPs. The results show that iron is inhomogeneously incorporated in the SiNPs leading to an efficient photoluminescence quenching. Emission arrives mainly from 2 nm size iron-free SiNPs.The nanoparticles were shown to generate singlet oxygen ( 1 O 2 ) upon 355 nm irradiation, though they were able to quench 1 O 2 . Analysis of cytotoxicity using MTT assay on rat glioma C6 cells showed a strong dependence on the nature of the surface groups, as 100 g/ml of propylamine-terminated iron-containing SiNPs leads to 85% decrease in cell viability while equal amounts of surface oxidized particles induced a 35% of cell death.

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Our research objective is to develop superparamagnetic iron oxide nanoparticles and silicon nanoparticles as radiosensitizers for cancer therapy. After internalization by breast tumor cells and irradiation with X-rays, the nanoparticles were observed to enhance the oxidative stress in tumor cells. While silicon nanoparticles increase the reactive oxygen species production under X-ray treatment due to their incompletely oxidized surface, positively charged amino-functionalized silicon nanoparticles enhance the formation of mitochondrial reactive oxygen species formation because of their direct interaction with the mitochondrial membrane. On the other hand, uncoated and citrate-coated superparamagnetic iron oxide nanoparticles were found to increase the reactive oxygen species formation in X-ray treated tumor cells via two particular surface features, being, first, the leakage of iron ions and second, the catalytic activity of nanoparticle surfaces. Both may initiate the Haber-Weiss and Fenton reaction.On the other hand, incompletely coated or uncoated superparamagnetic iron oxide nanoparticles (SPIONs) may promote the generation of ROS via different pathways. One occurs through the release of iron ions into the cytosol where immediate chelation by citrate or adenosine phosphate will take place [16][17][18][19]. Chelated iron ions can participate in the Haber-Weiss chemistry and thus, will catalyze the formation of the highly reactive hydroxyl radical that