US Patent 7228094 - Nanopowder on substrate

http://www.freepatentsonline.com/7228094.html

Yipes! This patent claim from Xerox is directed to a donor used in electrophotography processes but some of the claims appear quite broad.

1. A donor member comprising a substrate and having thereover a coating comprising a nano-size powder having a particle size of from about 25 to about 500 nanometers.

Although the specification of "donor member" may limit the breadth somewhat, many publications to metallic, magnetic, carbon-based, or other nanoparticle films formed on a substrate that would be in the cited range can be found by doing a quick survey of GoogleScholar prior to the priority date of this patent. See for example:
http://www.springerlink.com/content/g554625k1707l80h/