The fate of nano-ZnO and its bulk counterpart in the body of microscopic nematodes: An X-ray spectrometric study Zoltán Sávoly a, ⁎, Günter Buzanich b , Giancarlo Pepponi c , Christina Streli d , Krisztina Hrács e , Péter I. Nagy e , Gyula Záray f a Institute of Enzimology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok körútja 2, Budapest H-1117, Hungary b Federal Institute for Materials Research and Testing, Unter den Eichen 87, Berlin D-12205, Germany c MiNALab, Centre for Materials and Microsystems, Fondazione Bruno Kessler, Via Sommarive 18, Trento I-38123, Italy d Atominstitut, Vienna University of Technology, Stadionallee 2, Vienna A-1020, Austria e Department of Zoology and Animal Ecology, Szent István University, Páter Károly utca 1, Gödöllő H-2100, Hungary f Department of Analytical Chemistry, Eötvös Loránd University, Pázmány Péter sétány 1/A, Budapest H-1117, Hungary abstract article info Article history: Received 10 August 2014 Accepted 14 August 2014 Available online 30 August 2014 Keywords: Nematode Elemental distribution X-ray absorption near edge structure (XANES) ZnO nanoparticles Zinc detoxification The distribution and speciation of zinc were studied in the body of female specimens of the soil-inhabiting, plant-feeding nematode, Xiphinema vuittenezi treated with nano-ZnO and its bulk counterpart. Lyophilized nematodes were studied by X-ray absorption near edge structure spectrometry (XANES) in order to characterize the zinc speciation. Furthermore, in the cross-sections prepared by focused ion beam technique, elemental maps were obtained using the electron probe microanalysis (EPMA) technique. XANES spectra were collected from three different regions (head, midbody and tail region) of nematodes in case of two different treatments (50 mg/L bulk and nano-ZnO suspension, 24 h long treatment). The sample spectra were fitted by the spectra of several reference compounds, the main components of the fitted spectra are the following in all cases: bulk/ nano-ZnO; Zn–His and Zn 3 (PO 4 ) 2 * xH 2 O. Consequently, partial biotransformation takes place for both treatments, histidine- and phosphate-rich ligands play dominant role in the binding of zinc. According to the result of the EPMA analysis, it can be established that the distribution of zinc correlates with the calcium and phosphorus distribution for both treatments. Considering the results of the investigations performed by the two microanalytical techniques, it is likely that calcium phosphate granules were formed in order to bind zinc and hereby to take part in zinc detoxification. Apparent difference in the behavior of bulk and nano-sized ZnO in the body of the investigated nematodes was not found. © 2014 Elsevier B.V. All rights reserved. 1. Introduction Due to their unique physical and chemical properties, nanoparticles (NPs) are applied in several fields of our life. However, their increasing production poses a significant risk, and our knowledge on their uptake by organisms and toxicity is relatively poor. NPs may have deleterious effect on the human health as well as the environment. The new scientific areas studying the risk and effect of NPs on biota and habitats, such as nanotoxicology and nanoecotoxicology are obviously at their infancy [1]. NPs affect biological systems for at least three different reasons: i.) They can be toxic due to their chemical composition, if the given NP is soluble and contains toxic element. Brunner et al. found that solubility influences strongly the cytotoxicity of oxide nanoparti- cles [2]. ii.) The shape of the NPs also affects their toxicity. iii.) Finally, NPs generate reactive oxygen species (ROS). The significant ROS production is caused by the considerably high surface to volume ratio of the NPs comparing them with their bulk counterparts. ROS genera- tion results in protein, DNA and membrane injury on the cell level, and it causes several health problems, such as airway inflammation and interstitial fibrosis [3]. Other properties of the NPs can also affect their toxicity, such as rate of aggregation, presence and type of surface coating. ZnO nanoparticles have unique optoelectronic properties, which make them attractive for application as electronic devices. Recently, ZnO nanopowder is applied in plenty of products, for instance glass, ceramics, cement, lubricants, plastics, rubber, and pigments, moreover foods can contain it as zinc nutrient [4]. Bulk ZnO has been used in sunscreens for a long time, this compound is even more effective if applied in nanoparticulate form. This is a good example for the advantage of NPs against their bulk counterparts [5]. The effect of ZnO NPs on human cells [6] is being currently investigated as well as their ecotoxicity [4]. For the latter purpose, several plants and animals were applied, such as the ryegrass, Lolium perenne [7] and the collembola, Folsomia candida [8]. Microchemical Journal 118 (2015) 80–87 ⁎ Corresponding author. Tel.: +36 304203456. E-mail address: zoltan.savoly@gmail.com (Z. Sávoly). http://dx.doi.org/10.1016/j.microc.2014.08.011 0026-265X/© 2014 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Microchemical Journal journal homepage: www.elsevier.com/locate/microc