Luminescent nanoparticles leave a glowing fingerprint

Nanoparticles with long-lived luminescence have been shown to provide sharp images of otherwise invisible fingerprints, offering better resolution than does standard fingerprinting for forensic investigation, the researchers say (Anal. Chem. 2017, DOI: 10.1021/acs.analchem.7b03003). Quan Yuan of Wuhan University and colleagues synthesized Zn₂GeO₄ nanorods containing 1.0% gallium and 0.5% manganese that are similar to persistently luminescent nanoparticles they have used for biomedical imaging. The researchers modified the nanoparticle surface with activated esters that can bond to amino acids left behind in the ridges of fingerprints. Fingerprints developed with the glowing nanoparticles show more defined ridges than ones dusted with conventional black fingerprint powder. The particles also reveal clear fingerprints even 60 days after the prints are deposited—a potential benefit of this approach since the proteins, oils, and perspiration that form invisible fingerprints decompose over time, making the detection of aged prints with traditional techniques challenging. Yuan says a forensic research institute in Beijing is interested in further testing the nanoparticles.