Researchers at Iowa State University recently published the results of a study into whether nanoparticles can be used to deliver DNA into plant cells. The scientists found that porous, DNA coated, 100-200 nm diameter, silica nanoparticles entered into protoplasts (plant cells without cell walls) without causing any toxic effects.  These same nanoparticles, however, would not enter into intact plant tissue cells until the particles’ pores were capped with surface-functionalized gold nanoparticles.   Once capped, the nanoparticles also entered into intact plant cells.  The scientists theorized that the gold nanoparticle caps added extra density allowing the molecules to penetrate the intact cell walls. The scientists further concluded that these these types of nanoparticles could be used to deliver into plant cells(i) DNA via their coating, and (ii) "biogenic moieties" contained inside the hollow spaces of the nanoparticles themselves. The study ended with the observation that this research is a first step in demonstrating that nanoparticles may be of use in the field of plant genomics to improve crop species.

F. Torney, et al., “Mesoporous silica nanoparticles deliver DNA and chemicals into plants,” Nature Nanotechnology, Vol. 2, May 2007.