title: Size-dependent in vivo toxicity of PEG-coated gold nanoparticles.
abstract: BACKGROUND
  Gold nanoparticle toxicity research is currently leading towards the in vivo experiment. Most toxicology data show that the surface chemistry and physical dimensions of gold nanoparticles play an important role in toxicity. Here, we present the in vivo toxicity of 5, 10, 30, and 60 nm PEG-coated gold nanoparticles in mice.
  
  
  METHODS
  Animal survival, weight, hematology, morphology, organ index, and biochemistry were characterized at a concentration of 4000 μg/kg over 28 days.
  
  
  RESULTS
  The PEG-coated gold particles did not cause an obvious decrease in body weight or appreciable toxicity even after their breakdown in vivo. Biodistribution results show that 5 nm and 10 nm particles accumulated in the liver and that 30 nm particles accumulated in the spleen, while the 60 nm particles did not accumulate to an appreciable extent in either organ. Transmission electron microscopic observations showed that the 5, 10, 30, and 60 nm particles located in the blood and bone marrow cells, and that the 5 and 60 nm particles aggregated preferentially in the blood cells. The increase in spleen index and thymus index shows that the immune system can be affected by these small nanoparticles. The 10 nm gold particles induced an increase in white blood cells, while the 5 nm and 30 nm particles induced a decrease in white blood cells and red blood cells. The biochemistry results show that the 10 nm and 60 nm PEG-coated gold nanoparticles caused a significant increase in alanine transaminase and aspartate transaminase levels, indicating slight damage to the liver.
  
  
  CONCLUSIONS
  The toxicity of PEG-coated gold particles is complex, and it cannot be concluded that the smaller particles have greater toxicity. The toxicity of the 10 nm and 60 nm particles was obviously higher than that of the 5 nm and 30 nm particles. The metabolism of these particles and protection of the liver will be more important issues for medical applications of gold-based nanomaterials in future.
authors: Institute of Radiation Medicine, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin Key Laboratory of Molecular Nuclear Medicine, Tianjin, People's Republic of China.
authors: Xiao-Dong
authors: XD
authors: Zhang
authors: Di
authors: D
authors: Wu
authors: Xiu
authors: X
authors: Shen
authors: Pei-Xun
authors: PX
authors: Liu
authors: Na
authors: N
authors: Yang
authors: Bin
authors: B
authors: Zhao
authors: Hao
authors: H
authors: Zhang
authors: Yuan-Ming
authors: YM
authors: Sun
authors: Liang-An
authors: LA
authors: Zhang
authors: Fei-Yue
authors: FY
authors: Fan
mesh_terms: D000818:Animals; D001773:Blood Cells / Q000187:drug effects / Q000378:metabolism; D001835:Body Weight / Q000187:drug effects; D006046:Gold / Q000008:administration & dosage / Q000633:toxicity; D006400:Hematocrit; D007275:Injections, Intravenous; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D053768:Metal Nanoparticles / Q000008:administration & dosage / Q000633:toxicity; D051379:Mice; D008807:Mice, Inbred BALB C; D050997:Nanomedicine; D009929:Organ Size / Q000187:drug effects; D010316:Particle Size; D011092:Polyethylene Glycols / Q000008:administration & dosage / Q000633:toxicity; D013154:Spleen / Q000187:drug effects / Q000378:metabolism; D014018:Tissue Distribution
chemical_list: D011092:Polyethylene Glycols; D006046:Gold