Luminescent Marker for GSR: Evaluation of the Acute Oral and Inhalation Toxicity of the MOF [Eu(DPA)(HDPA)]

Abstract

The metal–organic framework (MOF) [Eu­(DPA)­(HDPA)] (where DPA is dipicolinic acid) has been previously reported as an efficient marker for gunshot residues (GSRs). Since this marker will be in contact with various shooters, industrial workers, and the environment, however, it is important to identify its toxicity. In this work, the oral and the inhalation acute toxicities of the MOF [Eu­(DPA)­(HDPA)] (also called R-Marker) were evaluated in young Wistar rats using Guidelines 423 (oral) and 436 (inhalation) from the Organisation for Economic Co-operation and Development (OECD). Animal behavior; body weight, water, and food intake; and organ weight, as well as biochemical parameters were evaluated in both evaluations. For the inhalation test, a concentration of 1 mg·Lair –1·(4 h–1) was reached in a whole-body inhalation chamber. When the respiratory tract was analyzed, it was observed that part of the marker had been swallowed instead of inhaled by the animal. For the oral test, the highest administrated dose was 2000 mg/kg with no sign of toxicity. This marker has been classified in the least toxic category of the Globally Harmonized System (GHS; category 5), with an oral median lethal dose (LD50) of 5000 mg/kg. After the oral administration, the feces of the animals were collected using a metabolic cage. Luminescent feces were present up to 24 h after administration, indicating that the marker had been excreted by the organism without causing intoxication. This study has opened perspectives for drug delivery and toxicity studies, since it enables visual detection of the marker.

Toxicity of metal–organic framework nanoparticles: from essential analyses to potential applications

“…In 2020, Weber et al conducted acute oral and inhalation tests in rats with the luminescent MOF Eu(DPA)(HDPA), which had previously been found as efficient marker for gunshot residues. 39 The authors could not detect any clinical or pathological signs of toxicity, signs of irritation or inflammation. Also in 2020, Horcajada et al were the first to investigate the toxic effect caused by the dermal exposure of patches of two different MOFs, namely MIL-100 (Fe) and MIL-127 (Fe), to human volunteers.…”

“…The 'Top 10 MOFs' analysed in toxicity studies, namely MIL-100, UiO-66, ZIF-8, MIL-88B, MIL-101, MIL-88A, MOF-74, HKUST-1, MOF-5, and UiO-67 (Figure 6), contain nine different metals Mg, Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, and Zr, but also various other MOF nanoparticles with metals such as Ca, 57 Ti, 33 Bi, 58 Eu, 39 Gd, 38 and Tb 23 have been studied. Based on their reported toxicity data, these MOFs can roughly be ranked in terms of their cytotoxic effect (Figure 11).…”

Interpol Review of Gunshot Residue 2019 to 2021

“…The toxicity of this type of product (luminescent markers) has already been the subject of several studies, in most cases by assessing their toxicity directly on mice or rats. In this respect, Talhari et al [ 63 ] examined the toxicity of a europium-based compound previously presented as a compound of interest among luminescent markers. Their study concludes that this compound ranks among the least toxic of the compounds studied to date.…”

Virtual Issue on Multifunctional Nanoporous Materials in Latin America

“…Highly stable MOFs with robust emission signals can be used for solid-state lighting, thermal-sensing, 8 or markers of gunshot residues in forensics, 9 with low toxicity. 10 Interestingly, new models that predict the optical properties of ligands in the presence of ions have been developed, opening the way to pretailored optically active MOFs. 11 MOF thin films that combine size-dependent properties with functionalized substrates lead to nanotechnological devices.…”

“…An adequate choice is luminescent lanthanide ions presenting well-defined optical transitions with antenna-like linkers that permit color tuning and improve photoluminescence. Highly stable MOFs with robust emission signals can be used for solid-state lighting, thermal-sensing, or markers of gunshot residues in forensics, with low toxicity . Interestingly, new models that predict the optical properties of ligands in the presence of ions have been developed, opening the way to pretailored optically active MOFs …”