Exploration of functionalized CdTe nanoparticles for latent fingerprint detection.

The potential of using water-soluble photoluminescent nanoparticles of different sizes for latent fingerprint detection has been explored. In this pilot study, green (582 nm) and red (755 nm) CdTe nanocrystals coated with thioglycolic acid were used. Latent fingerprints on aluminum and glass surfaces were successfully labeled with these nanoparticles for time periods ranging from 30 min to 24 h. The labeling is probably due to the amidation reaction between the surface carboxylic groups of the nanoparticles with the amine groups of the biomaterials present in the fingerprint residues. The 582 nm emitting nanoparticles appeared to better label the fingerprint ridges than did the 755 nm emitting ones for both surfaces. However, the 755 nm emitting nanoparticles were able to target the sweat pores within the ridges of the fingerprints. Other than high quantum yield and photostability, the tunable emission wavelength, the narrow bandwidth, the customizable surface characteristics, and the relatively long fluorescence decay lifetime of these nanoparticles are useful and necessary features for the future development of ultra-sensitive, target-specific, background suppressed latent fingerprint detection for forensic applications.