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

Table 1 Particle characterization

Particle description^a	Specific surface area^b [m² g⁻¹]	Hydrodynamic diameter [nm] in H2O^c in CM^d		Shape^e	Endotoxin contamination^f [EU per 250 μg particles]
7-nm SAS	326	147 (105–193)^g	147 ± 5	Irregular	< LOD^h
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 PS^k	Not measured	104(91–114)	Not measured	Spherical	Not measured

^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)
^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
^cDetermined using Nanoparticle Tracking Analysis 2.3 on a NanoSight instrument (Malvern)
^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
^eDetermined by transmission electron microscopy (TEM)
^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
^gNumbers in parenthesis show the 10% and 90% probability range
^hLOD, limit of detection (0.005 EU ml⁻¹)
ⁱThis endotoxin finding obtained with a purchased batch of polystyrene (PS) particles is included to show an example of contaminated commercial material
^kThese 100-nm traceable standard particles from Thermo Scientific served as a size standard for hydrodynamic diameter measurements by Nanoparticle Tracking Analysis

ISSN: 1743-8977