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Table 1 Particle characterization

From: MyD88-dependent pro-interleukin-1β induction in dendritic cells exposed to food-grade synthetic amorphous silica

Particle descriptiona Specific surface areab [m2 g−1] Hydrodynamic diameter [nm] in H2Oc in CMd Shapee Endotoxin contaminationf [EU per 250 μg particles]
7-nm SAS 326 147 (105–193)g 147 ± 5 Irregular < LODh
13-nm SAS 175 182 (130–241) 127 ± 1 Irregular < LOD
11-nm FePO4 188 183 (124–267) 255 ± 35 Irregular < LOD
21-nm FePO4 98 178 (110–258) 230 ± 40 Irregular 0.006
33-nm TiO2 47 205 (91–335) 67 ± 18 Almost spherical < LOD
140-nm TiO2 11 Not measured 352 ± 6 Almost spherical < LOD
50-nm PS-NH2 i Not measured Not measured Not measured Spherical 0.043
100-nm PSk Not measured 104(91–114) Not measured Spherical Not measured
  1. aThe primary particle diameter was calculated from specific surface area and weight (2.6 kg m−3 for SAS, 2.9 kg m−3 for FePO4 and 3.9 kg m−3 for TiO2)
  2. bCalculated from nitrogen adsorption (Micromeritics Tristar 3000) at 77 K and relative pressure range p/p0 = 0.05–0.25 using the Brunauer-Emmett-Teller (BET) theory
  3. cDetermined using Nanoparticle Tracking Analysis 2.3 on a NanoSight instrument (Malvern)
  4. dDetermined by dynamic light scattering using a Zetasizer Nano ZS (Malvern). CM, complete cell culture medium; values are reported as mean ± standard deviation (n = 3) and remained stable during 24 h
  5. eDetermined by transmission electron microscopy (TEM)
  6. fDetermined in the Endosafe PTS endotoxin test (Charles River). A control with Escherichia coli LPS at the concentration of 10 pg ml−1 yielded 0.037 EU ml−1; EU, endotoxin units
  7. gNumbers in parenthesis show the 10% and 90% probability range
  8. hLOD, limit of detection (0.005 EU ml−1)
  9. iThis endotoxin finding obtained with a purchased batch of polystyrene (PS) particles is included to show an example of contaminated commercial material
  10. kThese 100-nm traceable standard particles from Thermo Scientific served as a size standard for hydrodynamic diameter measurements by Nanoparticle Tracking Analysis