Intestinal absorption and biological effects of orally administered amorphous silica particles

Tokuyuki Yoshida,Shin-Ichi Tsunoda,Yohei Mukai,Hideki Takahashi,Yasuo Yoshioka,Kazuki Misato,Haruhiko Kamada,Kazuma Higashisaka,Takahide Mori,Toshiro Hirai,Yasuo Tsutsumi,Kazuya Nagano,Yasuhiro Abe,Hiromi Nabeshi,Tomoaki Yoshikawa

doi:10.1186/1556-276x-9-532

Abstract

Although amorphous silica nanoparticles are widely used in the production of food products (e.g., as anticaking agents), there is little information available about their absorption and biological effects after oral exposure. Here, we examined the in vitro intestinal absorption and in vivo biological effects in mice of orally administered amorphous silica particles with diameters of 70, 300, and 1,000 nm (nSP70, mSP300, and mSP1000, respectively) and of nSP70 that had been surface-modified with carboxyl or amine groups (nSP70-C and nSP70-N, respectively). Analysis of intestinal absorption by means of the everted gut sac method combined with an inductively coupled plasma optical emission spectrometer showed that the intestinal absorption of nSP70-C was significantly greater than that of nSP70. The absorption of nSP70-N tended to be greater than that of nSP70; however, the results were not statistically significant. Our results indicate that silica nanoparticles can be absorbed through the intestine and that particle diameter and surface properties are major determinants of the degree of absorption. We also examined the biological effects of the silica particles after 28-day oral exposure in mice. Hematological, histopathological, and biochemical analyses showed no significant differences between control mice and mice treated with the silica particles, suggesting that the silica nanoparticles evaluated in this study are safe for use in food production.

Highlights

Nanomaterials are currently used in a variety of applications, including the production of food products
56-nm silver nanoparticles have been found to be distributed in rat liver, kidney, brain, lung, and blood after 90 days of oral exposure at doses of 30, 125, or 500 mg/kg, and a no-observed-adverse-effect level (NOAEL) of 30 mg/kg and a lowest-observed-adverse-effect level (LOAEL) of 125 mg/kg have been suggested for these nanoparticles [4]
Silica particles We evaluated the following particles purchased from Micromod Partikeltechnologie, Rostock/Warnemünde, Germany: amorphous silica nanoparticles with a diameter of 70 nm, microsilica particles with diameters of 300 or 1,000 nm, and nSP70 that had been surface-modified with carboxyl or amine groups

Summary

Introduction

Nanomaterials are currently used in a variety of applications, including the production of food products. Assessments of the absorption and biological effects of nanomaterials after oral exposure are urgently needed. The information currently available about the biological effects and absorption of nanomaterials after oral exposure is limited. There is little information about the intestinal absorption and biological effects of silica nanoparticles after oral exposure. An efficient method to determine the absorption of silica particles in the human body is yet to be established. To evaluate the safety of silica nanoparticles after oral exposure, practical in vitro methods that allow prediction of the in vivo intestinal absorption and biological effects of silica nanoparticles after long-term oral exposure are urgently needed

Methods

Results

Discussion

Conclusion