Use of quantum dots in aqueous solution to detect blood fingermarks on non-porous surfaces

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.forsciint.2009.06.005 Byline: Andy Becue, Sebastien Moret, Christophe Champod, Pierre Margot Keywords: Detection; Latent fingermarks; Blood; Nanoparticles; Quantum dots; Luminescence; Acid Yellow 7 Abstract: A new and original reagent based on the use of highly fluorescent cadmium telluride (CdTe) quantum dots (QDs) in aqueous solution is proposed to detect weak fingermarks in blood on non-porous surfaces. To assess the efficiency of this approach, comparisons were performed with one of the most efficient blood reagents on non-porous surfaces, Acid Yellow 7 (AY7). To this end, four non-porous surfaces were studied, i.e. glass, transparent polypropylene, black polyethylene, and aluminium foil. To evaluate the sensitivity of both reagents, sets of depleted fingermarks were prepared, using the same finger, initially soaked with blood, which was then successively applied on the same surface without recharging it with blood or latent secretions. The successive marks were then cut in halves and the halves treated separately with each reagent. The results showed that QDs were equally efficient to AY7 on glass, polyethylene and polypropylene surfaces, and were superior to AY7 on aluminium. The use of QDs in new, sensitive and highly efficient latent and blood mark detection techniques appears highly promising. Health and safety issues related to the use of cadmium are also discussed. It is suggested that applying QDs in aqueous solution (and not as a dry dusting powder) considerably lowers the toxicity risks. Author Affiliation: Institut de Police Scientifique, School of Criminal Sciences, Batochime, University of Lausanne, CH-1015 Lausanne, Switzerland Article History: Received 30 March 2009; Revised 29 May 2009; Accepted 5 June 2009