Tohoku J. Exp. Med., 2012 Dec, 228(4)

Development of Silica-Coated Silver Iodide Nanoparticles and Their Biodistribution

YU SAKURAI,¹ HIROSHI TADA,¹ KOHSUKE GONDA,² MOTOHIRO TAKEDA,^1,2 LIMAN CONG,² MASAKAZU AMARI,^1,2 YOSHIO KOBAYASHI,³ MIKA WATANABE,⁴ TAKANORI ISHIDA¹ and NORIAKI OHUCHI^1,2

¹Department of Surgical Oncology, Graduate School of Medicine, Tohoku University, Sendai, Japan
²Department of Nano-Medical Science, Graduate School of Medicine, Tohoku University, Sendai, Japan
³Department of Biomolecular Functional Engineering, College of Engineering, Ibaraki University, Hitachi, Ibaraki, Japan
⁴Department of Pathology, Tohoku University Hospital, Sendai, Japan

Nanomaterials have great potential in the field of medicine and have been studied extensively. In a previous study, we addressed the potential of silver iodide (AgI) as X-ray contrast media, because it possessed high imaging ability in the measurement by X-ray computed tomography (X-CT) in vitro, and its surface can be modified with many functional groups. We developed the method of silica coating to make AgI nanoparticles more stable and uniform in size. However, the safety and metabolism of nanoparticles in vivo remains to be determined. The objective of the present study was to evaluate the in vivo biodistribution of silica-coated AgI nanoparticles (SAgINPs). X-CT, transmission electron microscopy (TEM), and inductively coupled plasma atomic emission spectrometry (ICP-AES) were performed prior to and at intervals following the intravenous administration of SAgINPs to rats and rabbits. ICP-AES is a spectral technique that can determine the presence and concentrations of metal samples. The X-CT study showed long-period enhancement in the liver and spleen, but not in the bladder of rats. The TEM study demonstrated that SAgINPs were found in hepatocytes. Using ICP-AES, Ag was detected in the bile juice of rabbits, but not found in the urine of these animals, suggesting that SAgINPs are excreted via the liver. This study shows the quantitative biodistribution of silica-coated nanoparticles for the first time, indicating that our silica coating technique is useful for development of nanoparticles with hepatic excretion. In conclusion, the SAgINPs may provide X-ray contrast media with high imaging ability and biocompatibility.

keywords —— biodistribution; contrast media; hepatic metabolism; nanoparticles; silica coating

© 2012 Tohoku University Medical Press

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Tohoku J. Exp. Med., 2012, 228, 317-323

Correspondence: Kohsuke Gonda, Department of Nano-Medical Science, Graduate School of Medicine, Tohoku University, 1-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8574, Japan.

e-mail: gonda@med.tohoku.ac.jp