Processing Pathway Dependence of Amorphous Silica Nanoparticle Toxicity: Colloidal vs Pyrolytic

详细信息    查看全文

• 作者：Haiyuan Zhang ; Darren R. Dunphy ; Xingmao Jiang ; Huan Meng ; Bingbing Sun ; Derrick Tarn ; Min Xue ; Xiang Wang ; Sijie Lin ; Zhaoxia Ji ; Ruibin Li ; Fred L. Garcia ; Jing Yang ; Martin L. Kirk ; Tian Xia ; Jeffrey I. Zink ; Andre Nel ; C. Jeffrey Brinker
• 刊名：The Journal of the American Chemical Society
• 出版年：2012
• 出版时间：September 26, 2012
• 年：2012
• 卷：134
• 期：38
• 页码：15790-15804
• 全文大小：863K
• 年卷期：v.134,no.38(September 26, 2012)
• ISSN：1520-5126

文摘

We have developed structure/toxicity relationships for amorphous silica nanoparticles (NPs) synthesized through low-temperature colloidal (e.g., St枚ber silica) or high-temperature pyrolysis (e.g., fumed silica) routes. Through combined spectroscopic and physical analyses, we have determined the state of aggregation, hydroxyl concentration, relative proportion of strained and unstrained siloxane rings, and potential to generate hydroxyl radicals for St枚ber and fumed silica NPs with comparable primary particle sizes (16 nm in diameter). On the basis of erythrocyte hemolytic assays and assessment of the viability and ATP levels in epithelial and macrophage cells, we discovered for fumed silica an important toxicity relationship to postsynthesis thermal annealing or environmental exposure, whereas colloidal silicas were essentially nontoxic under identical treatment conditions. Specifically, we find for fumed silica a positive correlation of toxicity with hydroxyl concentration and its potential to generate reactive oxygen species (ROS) and cause red blood cell hemolysis. We propose fumed silica toxicity stems from its intrinsic population of strained three-membered rings (3MRs) along with its chainlike aggregation and hydroxyl content. Hydrogen-bonding and electrostatic interactions of the silanol surfaces of fumed silica aggregates with the extracellular plasma membrane cause membrane perturbations sensed by the Nalp3 inflammasome, whose subsequent activation leads to secretion of the cytokine IL-1尾. Hydroxyl radicals generated by the strained 3MRs in fumed silica, but largely absent in colloidal silicas, may contribute to the inflammasome activation. Formation of colloidal silica into aggregates mimicking those of fumed silica had no effect on cell viability or hemolysis. This study emphasizes that not all amorphous silicas are created equal and that the unusual toxicity of fumed silica compared to that of colloidal silica derives from its framework and surface chemistry along with its fused chainlike morphology established by high-temperature synthesis (>1300 掳C) and rapid thermal quenching.