Nanoparticles are used increasingly in consumer products and biomedical applications. Yet the cellular interaction mechanism at the molecular level is not well understood for nanomaterials of different size, shape and surface chemistry. Gold nanoparticles (Au-NPs), which have been explored extensively for various applications in recent years, are used as the model system to help understand the size-dependent biological effects of nanoparticles. Jurkat cells treated with Au-NPs ranging from 2 nm to 200 nm were studied. Whole genome expression measurements indicate size-dependent effects, including linear scaling and threshold effects. In addition, a non-linear pattern of gene responses that persisted over time were observed in 20-40 nm Au-NP treated cells. Gene function, promoter, and pathway analyses reveal differential signaling processes that are correlated with nanoparticle sizes. The size may play a role in cellular sorting of naturally occurring particulates, particle interaction with the receptors, intracellular transportation, signaling and stress responses.
STATEMENT OF GOVERNMENT SUPPORT
 This invention was made during work supported by NASA JRI grant, CSF Prostate Cancer SPORE award (NIH Grant P50 CA89520), NIH grant R21CA95393-01, DOD grant BC045345, and DARPA grant F1ATA05252M001, and the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. The government of the United States of America has certain rights in this invention.