Evidence of Translocation of Oral Zn Doped Magnetite Nanoparticles Across the Small Intestinal Wall of Mice and Deposition in Spleen: Unique Advantage in Biomedical Applications.

Nanomaterials have been widely applied in oral drug delivery. A number of indirect evidences suggest that nanoparticles can pass across gastrointestinal walls to enter the blood circulation system. However, there is still no direct evidence to prove that the intact nanoparticles can pass across gastrointestinal walls and the nanoparticles can retain their original structure after translocation across gastrointestinal walls. In the present study, the potential toxicity of dimercaptosuccinic acid coated Zn doped magnetite nanoparticles (DMSA-ZnFeO) in the spleen, stomach, and small intestine of mice has been investigated after 30 days of repeated intragastric administration. We provide first direct evidence that intact DMSA-ZnFeO can pass across the small intestinal barriers to enter blood circulation system and arrive in the spleen. In addition, our findings provide direct evidence that although the biotransformation of DMSA-ZnFeO occurs in vivo, some DMSA-ZnFeO retain their original structure after translocation across the small intestinal wall and deposition in the spleen. The results indicate the safety of DMSA-ZnFeO in the applications in mice at a 50 mg/kg dose and highlight the unique advantage of DMSA-ZnFeO in biomedical applications.