A small interfering RNA-gold nanorod complex that can cross the blood-brain barrier and turn off a gene that controls addiction might form the basis of a novel drug addiction treatment (Proc. Natl. Acad. Sci. USA, DOI: 10.1073/pnas.0901715106). The DARPP-32 gene triggers dopaminergic signals that lead to drug addiction, and using siRNAs to suppress it could help prevent addiction. But unprotected siRNAs degrade quickly in the body. To bypass that problem, Paras N. Prasad and coworkers at the State University of New York, Buffalo, electrostatically bound siRNA to gold nanorods and tested the complexes in an in vitro model of the human blood-brain barrier. "Within the cytoplasm of the cells, the siRNA freed itself and blocked the expression of the DARPP-32 gene by interacting with its messenger RNA before it could translate into the DARPP-32 protein," Prasad explains. The researchers plan to conduct in vivo studies next. Prasad says the ultimate goal is intravenous delivery of the siRNA-nanorod complex, but the complex could be directly delivered to the brain through a surgical incision. He adds that the nanorod approach may also be useful for treating neurological diseases that require drugs to be delivered to the brain.