NIR-responsive NaYF4:Yb,Er,Gd fluorescent upconversion nanorods for the highly sensitive detection of blood fingerprints

In this paper, the NaYF4:Yb,Er,Gd fluorescent upconversion nanorods (UCNRs) were successfully employed as a promising fluorescent label for the detection of blood fingerprints with high sensitivity, low background, high efficiency, and low toxicity on a range of substrates including non-infiltrating materials (glass, ceramic tile, aluminium foil, stainless steel sheet, coin and marble), and infiltrating materials (magazine cover and train ticket). To assess the efficiency of this approach, comparisons were performed with Acid Yellow 7 (AY7, an effective blood reagent) on above-mentioned eight substrates. The fingerprints were cut in halves and the halves treated separately with UCNRs and AY7. The results manifested that UCNRs were superior to AY7 on all test substrates. This work shows that UCNRs are a versatile fluorescent label for the detection of blood fingerprints in criminal science for individual identification. (C) 2016 Elsevier Ltd. All rights reserved.