Comparison of gene expression profiles in mice liver following intravenous injection of 4 and 100 nm-sized PEG-coated gold nanoparticles

Gold nanoparticles (AuNPs) have been widely used in various biomedical applications for photothermal therapy, imaging and drug delivery. Although AuNPs have been recognized as a biologically safe material, very little is known about their molecular and cellular effects. To evaluate the gene expression profile and mechanism of the molecular level of polyethylene glycol (PEG)-coated AuNPs and the effect of particle size, we applied an expression profiling approach. PEG-coated AuNPs of different particle sizes, 4 and 100 nm, were intravenously administered to BALB/c mice (4.26 mg/kg, body weight). Thirty minutes after injection of AuNPs, the mice were sacrificed and liver tissues were removed. Then, pathological examination and microarray analysis were performed on the liver tissues. Histology of the liver tissues did not indicate any pathological changes in all treatment groups. Only 0.38% (170 genes) and 0.50% (224 genes) of the total genes (45,000 genes) were significantly induced by the treatment of 4 or 100 nm AuNPs, respectively. In addition, the 4 and 100 nm AuNPs treatment groups shared 67.1% and 50.9% of the significantly changed genes, respectively. Commonly expressed genes by a single intravenous injection of 4 or 100 nm AuNPs were categorized as apoptosis, cell cycle, inflammation, and metabolic process. In the specifically expressed genes of 4 or 100 nm AuNPs, although the genes were different each other, 4 and 100 nm AuNPs showed similar gene categories such as cell cycle, response to stress, signal transduction, and metabolic process. Therefore, we can conclude that 4 and 100 nm AuNPs showed similar biological effects on liver tissues of mice.