US Patent 7907809 - Ultra-low refractive index nanoparticle films

http://www.freepatentsonline.com/7907809.html

This patent from the University of Missouri includes some basic claims to a transparent nanoporous films useful to bioassays and optical applications. Claim 1 reads:

1. A nanoporous film comprising:

organosilica nanoparticles having a particle size from about 2 to about 5 nm and having a mean particle size of less than about 25 nanometers and a mean pore size of less than 10 nanometers;

wherein the film has a surface area of at least 500 m2/g and a porosity of at least about 50% by volume.