In vitro and in vivo evaluation of degradation, toxicity, biodistribution, and clearance of silica nanoparticles as a function of size, porosity, density, and composition.

Silica nanoparticles (SiO2 NPs) have potential utility in controlled release. Despite significant research in this area, there is a gap in the understanding of the correlation between SiO2 NP physicochemical properties on the one hand and their degradation in solutions, in cells, and in vivo on the other. Here, we fabricated SiO2 NPs with variations in size, porosity, density, and composition: 100 nm Stöber, 100 and 500 nm mesoporous, 100 nm disulfide-based mesoporous, and 100 nm disulfide-based hollow mesoporous. Degradation profiles over 28 days were investigated in simulated biological fluids and deionized water. Results show Meso 100, and 500 nanoparticles degraded faster at higher pH values. Results from macrophages indicate Meso 100 nanoparticles showed the highest degradation amount (~3.8%). Cytotoxicity evaluation of the particles in Human Aortal Endothelial Cells (HAECs) shows concentration-dependent toxicity for the particles. Results from CD-1 mice show ~53% of Meso 100 nanoparticles (25 mg kg-1) degraded and were detected in urine after seven days. It was shown nanoparticle porosity and composition as well as pH and ionic strength of the medium play the predominant roles for degradation of SiO2 NPs. Based on histological evaluations, at the injected doses investigated, the particles did not show toxicity.