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Silicon-containing nanoparticles (NPs) are considered promising drug carriers for targeted drug delivery. In this study, we investigated the physical and chemical properties of silicon-containing NPs, including silica and organomodified silica NPs (SiO2NPs and OrSiO2NPs, respectively), with different surface modifications, with the aim of increasing drug-loading efficiency. In addition, we described the original synthesis methods of different sizes of OrSiO2NPs, as well as new hybrid OrSiO2NPs with a silica core (SiO2 + OrSiO2NPs). Animal experiments revealed that the silicon-containing NPs investigated were non-toxic, as evidenced by a lack of hemodynamic response after intravenous administration. Bioelimination studies showed rapid renal excretion of OrSiO2NPs. In drug release kinetics studies, adenosine was immobilized on SiO2NPs using three different approaches: physical adsorption, ionic, and covalent bonding. We observed that the rate of adenosine desorption critically depended on the type of immobilization; therefore, adenosine release kinetics can be adjusted by SiO2NP surface modification technique. Adsorption of adenosine on SiO2 + OrSiO2NPs resulted in a significant attenuation of adenosine-induced hypotension and bradycardia. [ABSTRACT FROM PUBLISHER]

Over the last decade, magnetic iron oxide nanoparticles (IONPs) have drawn much attention for their potential biomedical applications. However, serious in vitro and in vivo safety concerns continue to exist. In this study, the effects of uncoated, Fe m O n -SiO 2 composite flake-like, and SiO 2 -Fe m O n core-shell IONPs on cell viability, function, and morphology were tested 48 h postincubation in human umbilical vein endothelial cell culture. Cell viability and apoptosis/necrosis rate were determined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and annexin V-phycoerythrin kit, respectively. Cell morphology was evaluated using bright-field microscopy and forward and lateral light scattering profiles obtained with flow cytometry analysis. All tested IONP types were used at three different doses, that is, 0.7, 7.0, and 70.0 μg. Dose-dependent changes in cell morphology, viability, and apoptosis rate were shown. At higher doses, all types of IONPs caused formation of binucleated cells suggesting impaired cytokinesis. Fe m O n -SiO 2 composite flake-like and SiO 2 -Fe m O n core-shell IONPs were characterized by similar profile of cytotoxicity, whereas bare IONPs were shown to be less toxic. The presence of either silica core or silica nanoflakes in composite IONPs can promote cytotoxic effects., Competing Interests: The authors report no conflicts of interest in this work.