Preparation and characterization of new photoluminescent nano-powder based on Eu 3+ :La 2 Ti 2 O 7 and dispersed into silica matrix for latent fingerprint detection

Cation Crosslinking-Induced Stable Copper Nanoclusters Powder as Latent Fingerprints Marker

Luminescent copper nanoclusters (Cu NCs) have shown great potential in light-emitting devices (LEDs), chemical sensing, catalysis and biological fields. However, their practical use has been restricted by poor stability, and study on the stability of Cu NCs solid powder along with the mechanism is absent. In this study, stablized Cu NCs powder was first obtained by cation crosslinking method. Compared with the powder synthesized by solvent precipitation method, the stability of Cu NCs powder crosslinked by ionic inducer Ce3+ was enhanced around 100-fold. The storage time when the fluorescence intensity decreased to 85% (T85) was improved from 2 h to 216 h, which is the longest so far. The results of characterizations indicated that the aggregation structure was formed by the binding of Ce3+ with the capping ligands of Cu NCs, which helped in obtaining Ce-Cu NCs powder from aggregate precipitation in solution. Furthermore, this compact structure could avoid the destruction of ambient moisture resulting in long-lasting fluorescence and almost unchanged physical form. This demonstrated that phosphor, with excellent characteristics of unsophisticated synthesis, easy preservation and stable fluorescence, showed great potential in light sources, display technology and especially in latent fingerprints visualization on different substrates for forensic science.

Novel fluorescent nano-sensor based on amino-functionalization of Eu3+:SrSnO3 for copper ion detection in food and real drink water samples

Lanthanide-doped nanoparticles exhibit unique optical properties and have been widely utilized for different sensing applications. Herein, the Eu3+:SrSnO3@APTS nanosensor was synthesized and its optical properties were analyzed using UV-Vis and photoluminescence spectroscopy. The TEM images of the synthesized nanophosphor Eu3+:SrSnO3@APTS exhibited peanut-like morphology, composed of two or more spherical nanoparticles with an average diameter ∼33 nm. Effects of environmental pH values and doping concentrations as well as amino functionalization on the structure of Eu3+:SrSnO3 were investigated. The as-synthesized optical nanosensor was used for determination of copper ions based on a fluorescence quenching approach. Red emission with a long lifetime was obtained in the case of the 0.06 mol Eu3+:SrSnO3@APTS sample. Under the optimal experimental conditions, a Stern-Volmer plot exhibited a good linearity for copper ions over the concentration (0.00-10.8) × 10-11 mol L-1 with a correlation efficient of 0.996 and a limit of detection 3.4 × 10-12 mol L-1. The fluorescent sensor was dynamically quenched via a coulombic interaction mechanism between the Eu3+ (5L6) and Cu2+. The Eu3+:SrSnO3@APTS nanosensor with the optimal Eu3+ dopant concentration of 0.06 mol was applied for copper determination in food and real drink water samples with high recovery values. We believe that the developed nanosensor probe can also be used for the detection of other toxic compounds, with high selectivity and sensitivity.

Barium tungstate doped with terbium ion green nanophosphor: Low temperature preparation, characterization and potential applications

Production of Nano-Terbium doped barium tungstate and its potential applications as a phosphor in forensic science and anti-counterfeiting ink applications have not been reported in the literature to now. Herein, simple, sensitive and bi-functional green Nanophosphor based on BaWO₄: xTb³⁺ was prepared and characterized for latent prints and anti-counterfeiting ink applications. High crystalline tetragonal BaWO₄ phase was obtained with nano-spherical morphology. BWO: xTb³⁺ Nanophosphors emits a strong and dual green and bluish green colors which appear to the human eye upon UVC and UVA excitation resources, respectively. The lifetime values were increased with rising Tb³⁺ ion concentrations from 0.01 to 0.07 mol. BWO: xTb³⁺ Nanophosphor has successfully visualized latent print from various forensic non-porous and porous surfaces. Moreover, BWO: xTb³⁺ Nanophosphor was used to develop luminescent ink for anti-counterfeiting application.