<p>Nano-SiO<sub>2</sub> particles were incubated with fetal bovine serum under the same conditions as those used to treat A549 cells. The nanoparticles were recovered and bound proteins identified by proteomics as described in Materials and Methods. The table lists the main proteins identified in each row (the 4 with the highest Sf scores; minimum score of 3.0) and the rows in which they were present. Underlined symbols indicate the row where the highest protein coverage was found. The MW equivalent to the centre of each row is indicated. The experiment was performed twice and also repeated in the presence of A549 cells. A similar result was found on each occasion, i.e. all proteins identified were bovine in origin and none could be attributed to a human source (i.e. A549 cells). MS details supporting the identification of the proteins are provided in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0072363#pone.0072363.s003" target="_blank">Table S2</a>.</p
