| With the rapid development of nanotechnology, nanomaterials have increasingly wide rang of applications in biomedical field; at the same time, the biological safety of nanomaterials gradually become the hot issue of global concern. Silica nanoparticles have been applied extensively in biomedical field due to its highly hydrophilic, easy to prepare and modified, and its biological effects have also received great attentions. In spite of what has been achieved so far, the relationship between the physicochemical properties and their biological effects of silica nanoparticles has no unified conclusion yet. Here we use fluorescently labelled silica particles(SP) to investigate the impact of particle size and surface modification on their in vivo and in vitro biological effects, with the expectation of providing suitable metrics to the biological effects of nanomaterials for reference, mainly involving the following two aspects:(1) A study on the toxicological mechanism of SP with different particle sizes and surface modifications in RAW264.7cells was conducted using flow cytometry to detect the intracellular reactive oxygen species, cell cycle, cell apoptosis, and western blot to analyze the expression level of related proteins, thus elucidating the effected cell signal pathways integratedly. Combined with the pre metabolomics and transcriptomics studies of SP of our group, we found that SP can induce oxidative stress in RAW264.7cells and SP30/70/300-plain induce cell cycle arrest in G0/G1, activate p53signal pathway and further caspase-3dependent apoptosis, resulting in nanotoxicity finally.(2) A study combined in vivo imaging, flow cytometry and confocal microscopy was conducted to investigate the distribution in mice and uptake in RAW264.7cells of fluorescently labelled SP70of different surface modifications. The results suggested that SP70with surface modification have an increasing distribution in the liver of mice and more uptake in RAW264.7cells than those not modified particles, along with the fact that-COOH modified SP are more prone to enter RAW264.7cells than-NH2modified ones. The endocytic mechanism study showed that SP70enter cells through energy-dependent manner, and the endocytosis of SP70-plain may be microfilament-dependent pinocytosis. The intracellular localization of SP70showed that SP70enter RAW264.7cells and localize in lysosomes and mitochondria, and SP70-COOH can also be found in the nucleus. |
