Assessment of metals bound to marine plankton proteins and to dissolved proteins in seawater

Studies based on laser ablation–inductively coupled plasma-mass spectrometry (LA–ICP-MS) have been performed to assess metal bound to dissolved proteins and proteins from marine plankton after two-dimensional polyacrylamide gel electrophoresis (2D PAGE). Dissolved proteins were pre-concentrated from surface seawater (60 L) by tangential ultrafiltration with 10 kDa molecular weight cut-off (MWCO) membranes and further centrifugal ultrafiltration (10 kDa) before proteins isolation by methanol/chloroform/water precipitation. Proteins isolation from plankton was assessed after different trichloroacetic acid (TCA)/acetone and methanol washing stages, and further proteins extraction with a phenol solution. LA–ICP-MS analysis of the electrophoretic profiles obtained for dissolved proteins shows the presence of Cd, Cr, Cu, and Zn in five spots analyzed. These proteins exhibit quite similar molecular weights (within the 10–14 kDa range) and pIs (from 5.8 to 7.3). Cd, Cr, Cu, and Zn have also been found to be associated to proteins isolated from plankton samples. In this case, Cd has been found to be bound to proteins of quite different molecular weight (9, 13 and 22 kDa) and pIs (4.5, 5.2, 5.5, and 10). However, trace elements such as Cr, Cu and Zn appear to be mainly bound to plankton proteins of low molecular weight and variable pI

Effects of Zinc Oxide Nanoparticle Exposure on Human Glial Cells and Zebrafish Embryos

Zinc oxide nanoparticles (ZnO NPs) are among the most widely used nanomaterials. They have multiple applications in cosmetics, textiles, paints, electronics and, recently, also in biomedicine. This extensive use of ZnO NPs notably increases the probability that both humans and wildlife are subjected to undesirable effects. Despite being among the most studied NPs from a toxicological point of view, much remains unknown about their ecotoxicological effects or how they may affect specific cell types, such as cells of the central nervous system. The main objective of this work was to investigate the effects of ZnO NPs on human glial cells and zebrafish embryo development and to explore the role of the released Zn2+ ions in these effects. The effects on cell viability on human A172 glial cells were assessed with an MTT assay and morphological analysis. The potential acute and developmental toxicity was assessed employing zebrafish (Danio rerio) embryos. To determine the role of Zn2+ ions in the in vitro and in vivo observed effects, we measured their release from ZnO NPs with flame atomic absorption spectrometry. Then, cells and zebrafish embryos were treated with a water-soluble salt (zinc sulfate) at concentrations that equal the number of Zn2+ ions released by the tested concentrations of ZnO NPs. Exposure to ZnO NPs induced morphological alterations and a significant decrease in cell viability depending on the concentration and duration of treatment, even after removing the overestimation due to NP interference. Although there were no signs of acute toxicity in zebrafish embryos, a decrease in hatching was detected after exposure to the highest ZnO NP concentrations tested. The ability of ZnO NPs to release Zn2+ ions into the medium in a concentration-dependent manner was confirmed. Zn2+ ions did not seem entirely responsible for the effects observed in the glial cells, but they were likely responsible for the decrease in zebrafish hatching rate. The results obtained in this work contribute to the knowledge of the toxicological potential of ZnO NPs.This research was funded by the Ministry of Science and Innovation: MCIN/AEI/10.13039/501100011033 (grant PID2020-114908GA-I00), Xunta de Galicia (ED431B 2022/16 and ED481A 2019/003 to A.A-G.), CICA-Disrupting Project 2021SEM-B2, and Ministry of Education, Culture and Sport (BEAGAL18/00142 to V.V.)

Inductively coupled plasma-optical emission spectrometry/mass spectrometry for the determination of Cu, Ni, Pb and Zn in seawater after ionic imprinted polymer based solid phase extraction

The capabilities of a synthesized ionic imprinted polymer (IIP), originally prepared for Ni recognition/pre-concentration from seawater, have been evaluated for other trace elements pre-concentration. The polymer has been synthesized by the precipitation polymerization technique using a ternary pre-polymerization complex formed by the template (Ni), the monomer (2-(diethylamino) ethyl methacrylate, DEM) and a non-vinylated chelating agent (8-hydroxyquinoline, 8-HQ). Since the complexing agent (8-HQ) is trapped into the polymeric matrix, but is not linked to the polymer chains, specific interactions between the functional groups (present in the monomer and the complexing agent) and other trace elements rather than Ni may occur. Results have shown that the IIP offers imprinting properties for the template (Ni(II)) and also for Cu(II), Pb(II), Zn(II), As(V) and Cd(II), with analytical recoveries close to 100% for all elements except for As(V) and Cd(II) (around 70%), whereas the non-imprinted polymer (NIP) did not show affinity for any trace element. In addition, the polymer does not interact with alkaline or alkaline-earth metals, so Na, K, Mg and Ca from the seawater salt matrix could be effectively removed. Variables affecting the IIP-solid phase extraction (SPE) process (pH, load flow rate and concentration and volume of the eluting solution) were completely studied. Inductively coupled plasma-optical emission spectrometry (ICP-OES) and inductively coupled plasma-mass spectrometry (ICP-MS) have been used as multi-element detectors. Acidified seawater samples must only be treated to fix an alkaline pH (8.5 ± 0.5) and passed through IIP-SPE cartridges. After seawater sample loading (250 mL), analytes were eluted with 2.5 mL of 2.0 M nitric acid, offering a pre-concentration factor of 100. Therefore, the limits of detection (LODs) of the method were 0.14, 0.15, 0.18 and 0.03 μg L-1, for Ni, Cu, Pb and Zn, respectively, when using ICP-OES detection and 0.0022, 0.0065, 0.0040 and 0.009 μg L-1, for Ni, Cu, Pb and Zn, respectively, for ICP-MS detection. Accuracy of the method was assessed by analyzing SLEW-3 (estuarine water), and TM-23.3 and TM-24 (lake water) certified reference materials. © 2009 Elsevier B.V. All rights reserved

Ionic imprinted polymer for nickel recognition by using the bi-functionalized 5-vinyl-8-hydroxyquinoline as a monomer Application as a new solid phase extraction support

A new ionic imprinted polymer (IIP) for Ni(II) recognition/pre-concentration was prepared via precipitation polymerization using 2-(diethylamino) ethyl methacrylate (DEM) and divinylbenzene (DVB) as a crosslinking agent in the presence of nickel(II) and 5-vynil-8-hydroxyquinoline (5-VHQ) as a bi-functionalized ligand. An important increase on the selectivity of the synthesised IIP for nickel(II) ions was obtained when comparing to the use of 8-hydroxyquinoline (8-HQ) as a ligand. The synthesised IIP was used as a new support for solid phase extraction (SPE) of nickel(II) from seawater before inductively coupled plasma optical emission spectrometry (ICP-OES) detection. Variables affecting the SPE process, such as pH, load and elution flow rates, and concentration and volume of the eluting solution, were fully evaluated. The optimised procedure consists of a sample loading (100 mL of seawater at a pH of 9.0 ± 0.1) through IIP-SPE cartridges containing 300 mg of the synthesised IIP at a flow rate of 3.0 mL min- 1. Elution was performed by passing 2.5 mL of 2.0 M nitric acid at a flow rate of 1.5 mL min- 1, which gave a pre-concentration factor of 40. The limit of detection (LOD) of the method was 0.26 μg L- 1, while the relative standard deviation (RSD) for eleven replicated measurements was 3%. Accuracy of the method was assessed by analyzing SLEW-3 (estuarine water) and TM-23.3 (lake water) certified reference materials. In addition to the selectivity of the synthesised material for nickel(II) ions against other transition metal ions and major alkaline and alkaline-earth metals (Na+, K+, Mg2+ and Ca2+) in seawater, it can be stated that the salt matrix is efficiently removed by using the proposed IIP-SPE procedure. © 2009 Elsevier B.V. All rights reserved

Synthesis, characterization and evaluation of ionic-imprinted polymers for solid-phase extraction of nickel from seawater

Several nickel ion imprinted polymers were prepared via precipitation polymerization using 4-vinylpyridine or 2-(diethylamino) ethyl methacrylate as monomers (vinylated reagents) and a cross-linking agent divinylbenzene in the presence of nickel(II) alone or nickel(II) and 8-hydroxyquinoline (non-vinylated reagent). For all cases, 2,2′-azobisisobutyronitrile (AIBN) was used as an initiator and an acetonitrile/toluene (31) mixture was chosen as a porogen. After packing the polymer particles into empty SPE cartridges, nickel(II) ions were removed by washing with 50 mL of 2.0 M nitric acid. Characterization of the polymer particles has been carried out by scanning electron microscopy, energy dispersive X-ray fluorescence and elemental analysis. The best nickel imprinting properties were given by polymers synthesized in the presence of 8-hydroxyquinoline and 2-(diethylamino) ethyl methacrylate as a monomer. The optimum pH for quantitative nickel retention was 8.5 ± 0.5, while elution was completed with 2.5 mL of 2.0 M nitric acid. When using polymer masses of 300 mg, sample volumes until 250 mL can be passed through the cartridges without reaching the breakthrough volume. Therefore, a pre-concentration factor of 100 has been reached when eluting with 2.5 mL of the elution solution. Electrothermal atomic absorption spectrometry has been used as a detector for nickel determination. The limit of detection of the method was 0.050 μg L-1 (pre-concentration factor of 100), while the relative standard deviation for eleven replicates was 6%. Accuracy of the method was assessed by analyzing different certified reference materials SLEW-3 (estuarine water) and TM-23.3 and TM-24 (lake water). © 2008 Elsevier B.V. All rights reserved