Subcellular partitioning kinetics, metallothionein response and oxidative damage in the marine mussel Mytilus galloprovincialis exposed to cadmium-based quantum dots Thiago Lopes Rocha a , Tânia Gomes a,b , Emerson Giuliani Durigon a , Maria João Bebianno a, ⁎ a CIMA, Faculty of Science and Technology, University of Algarve, Campus de Gambelas, 8005-139 Faro, Portugal b Norwegian Institute for Water Research (NIVA), Gaustadalléen 21, NO-0349 Oslo, Norway HIGHLIGHTS • Subcellular partitioning and MT re- sponse are Cd form, tissue and time de- pendent. • Tissue specific metabolism of Cd-based quantum dots (QDs) in marine mussels. • QDs are slower biologically detoxified when compared to dissolved Cd. • Subcellular partitioning and biomarker responses indicate nano-specific effects. • Subcellular partitioning is potential tool to assess nanomaterial ecotoxicity. GRAPHICAL ABSTRACT abstract article info Article history: Received 25 January 2016 Received in revised form 23 February 2016 Accepted 24 February 2016 Available online xxxx Editor: D. Barcelo The environmental health impact of metal-based nanomaterials is of emerging concern, but their metabolism and detoxification pathways in marine bioindicator species remain unclear. This study investigated the role of subcellular partitioning kinetics, metallothioneins (MTs) response and oxidative damage (lipid peroxidation – LPO) in the marine mussel Mytilus galloprovincialis exposed to CdTe quantum dots (QDs) in comparison with its dissolved counterpart. Mussels were exposed to QDs and dissolved Cd for 21 days at 10 μg Cd L -1 followed by a 50 days depuration. Higher Cd concentrations were detected in fractions containing mitochondria, nucleus and lysosomes, suggesting potential subcellular targets of QDs toxicity in mussel tissues. Tissue specific metabo- lism patterns were observed in mussels exposed to both Cd forms. Although MT levels were directly associated with Cd in both forms, QDs subcellular partitioning is linked to biologically active metal (BAM), but no increase in LPO occurred, while in the case of dissolved Cd levels are in the biologically detoxified metal (BDM) form, Keywords: Nanoparticles CdTe quantum dots Science of the Total Environment 554–555 (2016) 130–141 Abbreviations: 4-HNE, 4-hydroxyalkenals; BAM, biologically active metal; BCF, bioconcentration factor; BDM, biologically detoxified metal; C B , Cd concentration in the subcellular fractions; C B0 , initial Cd concentration; Cd-total, total Cd concentration; C W , Cd concentration in seawater; ENP, engineered nanoparticle; GPx, glutathione peroxidase; GST, glutathione-S-transferase; HMW, high molecular weight proteins; Ht, whole tissue homogenate; IF, insoluble fraction; K a , accumulation rate; K l , loss rate; LMS, lysosomal membrane sta- bility; LMW, low molecular weight protein; LPO, lipid peroxidation; MDA, malondialdehyde; MT, metallothionein; NP, nanoparticle; PCA, principal component analysis; QDs, quantum dots; SOD, superoxide dismutase; t 1/2 , half-life time. ⁎ Corresponding author. E-mail address: mbebian@ualg.pt (M.J. Bebianno). http://dx.doi.org/10.1016/j.scitotenv.2016.02.168 0048-9697/© 2016 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv