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Table 2 Summary of the material properties

From: Sub-chronic toxicity study in rats orally exposed to nanostructured silica

  Pristine material characterization
NM-202 SAS
General Hydrophilic pyrogenica Hydrophilic pyrogenica
Specific surface area 200 m2/ga 380 m2/ga
Purity ≥99.9%b ≥99.8%a
Primary particle size 10-25 nma 7 nma
SEM size distribution At least 61% of the material was <100 nm.c (Figure 1E) At least 78% of the material was <100 nm.c (Figure 1E)
XPS Si: 25.0 ± 0.3 at%b Si: 29.8 ± 0.5 at%
O: 72.1 ± 0.4 at% b O: 68.1 ± 0.6 at%
C: 2.9 ± 0.6 at% b C: 2.1 ± 0.6 at%
EDX Presence of carbon on the surface (Figure 1F). Presence of carbon on the surface (Figure 1F).
FTIR Large peak between 1000–1130 cm-1 and a peak at ~800 cm-2 corresponding to Si-O bonds in a pattern characteristic for amorphous fumed silica. Large peak between 1000–1130 cm-1 and a peak at ~800 cm-2 corresponding to Si-O bonds in a pattern characteristic for amorphous fumed silica.
Some C-H stretching vibrations at ~3000 cm-1, indicating the presence of organic material on the surface.  
  Material characterisation in the feed matrix
(HDC)-ICP-MS 79.6 ± 20.7 mg silica/g feed, ~100% between 5–200 nm 80.5 ± 20.9 mg silica/g feed, ~40% between 5–200 nm
SEM-EDX Presence of carbon on the material surface before and after in vitro digestion. Presence of carbon on the material surface before and after in vitro digestion.
Presence of salts (e.g. Ca and P, likely in the form of CaPO4) on the material surface after in vitro digestion. Presence of salts (e.g. Ca and P, likely in the form of CaPO4) on the material surface after in vitro digestion.
(Additional file 1: Figure S1) (Additional file 1: Figure S1)
  Material characterization in intestinal content
(HDC)-ICP-MS 81, 81, 97% (low, medium and high group respectively) of the material has a size between 5–200 nm 55, 106, 54% (low, medium and high group respectively) of the material has a size between 5–200 nm
Dissolution ~15-20 wt% or less dissolves after in vitro digestion. ~15-20 wt% or less dissolves after in vitro digestion.
  1. aAs specified by the manufacturer. bReported in ref [23]. cSize limit of detection at 25 nm.