To deliver genes into cells, scientists rely on engineered viruses, but these germs often provoke immune responses and make them potentially lethal. New silica nanoparticles with organic components may prove effective nonviral DNA carriers. Chemists at the University at Buffalo found that the electric charge on these nanoparticles held and compacted the DNA, protecting it from enzymatic digestion in cells. The organic components also render normally rigid silica nanoparticles more flexible and capable of releasing encapsulated biomolecules and might make the nanoparticles safely biodegradable as well. Nanoparticles with the gene for green fluorescent protein penetrated cultured monkey kidney cells, delivered the DNA once inside and successfully modified their genes. The investigators now are using the technique in mice to carry genes into nerve cells. Their report appeared in the January 11 issue of Proceedings of the National Academy of Sciences USA.