On p. 893 Luo and Saltzman test the idea that DNA transfection efficiency is limited by a simple physical barrier, getting DNA to the cell surface. Using dense silica nanoparticles, they were able to increase the concentration of DNA–transfection reagent complexes on cell surfaces by associating them with the nanoparticles, which settle under gravity on cells. This resulted in up to an 8.5-fold enhancement in vitro over the best commercially available transfection reagents. Such a simple approach to overcoming the physical limitations of transfection will most likely be used by many laboratories.