Nanoparticles appear in several areas of forensic science including security documents, paints, inks, and reagents that
develop latent prints. One reagent (known as the silver physical developer) that visualizes the water insoluble
components of latent print residue is based on the formation of highly charged silver nanoparticles. These attach to and
grow on the residue and generate a silver image. Another such reagent involves highly charged gold nanoparticles.
These attach to the residue forming a weak gold image which can be amplified with a silver physical developer.
Nanoparaticles are also used in items such as paints, printing inks, and writing inks. Paints and most printing inks
consist of nano-sized pigments in a vehicle. However, certain modern ink jet printing inks now contain nano-sized
pigments to improve their light fastness and most gel inks are also based on nano scale pigments. These nanoparticlecontaining
materials often appear as evidence and are thus subject to forensic characterization. Both luminescent
(quantum dots), up-converting nano scale phosphors, and non luminescent nanoparticles are used as security tags to label
product, add security to documents, and as anti counterfeiting measures. These assist in determining if an item is