[Synthesis of LaPO4∶Ce, Tb Fluorescent Nanopowders and Their Applications in Nondestructive Development of Latent Fingerprints].

LaPO4∶Ce, Tb fluorescent nanopowders with high quality were synthesized via a hydrothermal method. The size, phase, and fluorescent property of as-prepared fluorescent nanopowders were then characterized by transmission electron microscopy (TEM), powder X-ray diffraction (XRD) measurements, and fluorescence spectroscopy (FS). The fluorescent nanopowders were well-dispersed and rod-like in shape, with an average diameter of about 20 nm and an average length of about 700 nm. The fluorescent nanopowders were of pure monoclinic LaPO4 structure. They could emit strong green fluorescence under the 254 nm ultraviolet excitation. The LaPO4∶Ce, Tb fluorescent nanopowders were finally used as novel fluorescent labels for the nondestructive development of latent fingerprints on various smooth substrates, and the developing contrast, sensitivity, selectivity, as well as the background interference were also discussed in detail. The experimental results showed that the latent fingerprints labeled by LaPO4∶Ce, Tb fluorescent nanopowders could give strong green emissions under 254 nm ultraviolet lights, and thus well-defined friction ridges with sharp edges and some detailed features could be clearly observed, with high contrast, high sensitivity, high selectivity, and low background interference. It was shown that our development procedure was facile, effective and well applicable with outstanding performance. More importantly, the extraction and detection of DNA in fingerprint residues could also be achieved after fingerprint development, which was almost impossible to achieve by using the traditional used developing powders including metal powder, metallic powder, and fluorescent powder. Therefore, our work provides beneficial references for the full utilization of both fingerprints and DNA evidences.