Forensic Summary by Gina Gallucci
Porous silicon microparticles (pSi MPs) coupled with fluorescent dyes as well as intrinsically luminescent pSi MPs have emerged as a new technique for fingerprint dusting and development. These MPs have been widely used across the sciences for various uses including in vivo drug delivery due to biocompatibility. Luminescent pSi offers a higher photostability than the usual fluorescent powders. In addition, while fluorescent powders have lifetimes in the nanosecond range, these possess lifetime if microseconds. It also has a long, near-IR wavelength that can enhance fingerprint development as it allows the removal of background interference.
A depletion series of fingerprints was used. The pSi MPs were conjugated with fluorescent dyes, either carboxy-5-fluorescin or lissamine. A control was done to confirm fluorescence from the covalent attachment of these molecules. It was shown that the pSI MPs follow the ridge patterns of the latent prints. These intrinsically luminescent pSi MPs also give a large Stokes shift that yields a high contrast between the print and the substrate. Coupled with the long lifetime, these fluorescently conjugated pSi MPs showed good results for the dusting of latent fingerprints.
Guinan, Taryn M., Hilton Kobus, Yiqing Lu, Martin Sweetman, Steven J. P. Mcinnes, K. Paul Kirkbride, and Nicolas H. Voelcker. “Nanostructured Silicon-Based Fingerprint Dusting Powders for Enhanced Visualization and Detection by Mass Spectrometry.” ChemPlusChem 81.3 (2016): 258-61. Web.