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Dialdehyde cellulose nanofibrils (CNF) and nanocrystals (CNC) were prepared via periodate oxidation (CNF/CNC-ox) and subsequently functionalized with hexamethylenediamine (HMDA) via a Schiff-base reaction, resulting in partially crosslinked micro-sized (0.5-10 μm) particles (CNF/CNC-ox-HMDA) with an aggregation and sedimentation tendency in an aqueous media, as assessed by Dynamic Light Scattering and Scanning Electron Microscopy. The antibacterial efficacy, aquatic in vivo (to Daphnia magna) and human in vitro (to A594 lung cells) toxicities, and degradation profiles in composting soil of all forms of CNF/CNC were assessed to define their safety profile. CNF/CNC-ox-HMDA exhibited higher antibacterial activity than CNF/CNC-ox and higher against Gram-positive S. aureus than Gram-negative E. coli, yielding a bacteria reduction of >90 % after 24 h of exposure at the minimum (≤2 mg/mL), but potentially moderately/aquatic and low/human toxic concentrations (≥50 mg/L). The presence of anionic, un/protonated amino-hydrophobized groups in addition to unconjugated aldehydes of hydrodynamically smaller (<1 μm) CNC-ox-HMDA increased the reduction of both bacteria to log 9 at ≥4 mg/mL and their bactericidal activity. While only CNF/CNC-ox can be considered as biosafe and up to >80 % biodegradable within 24 weeks, this process was inhibited for the CNF/CNC-ox-HMDA. This indicated their different stability, application and disposal after use (composting vs. recycling)., Competing Interests: Declaration of competing interest The authors declare that they have no conflicts of interest to reveal., (Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Brine shrimp Artemia sp. has been recognised as an important ecotoxicity and nanotoxicity test model organism for salt-rich aquatic environments, but currently there is still no harmonised testing protocol which would ensure the comparable results for hazard identification. In this paper we aimed to design the harmonised protocol for nanomaterial toxicity testing using Artemia franciscana and present a case study to validate the protocol with silver nanoparticles (AgNPs). We (i) revised the existing nanotoxicity test protocols with Artemia sp. (ii) optimised certain methodological steps based on the experiments with AgNPs and potassium dichromate (K2Cr2O7) as a soluble reference chemical and (iii) tested the optimised protocol in an international inter-laboratory exercise conducted within the EU FP7 NanoValid project. The intra- and inter-laboratory reproducibility of the proposed protocol with a soluble reference chemical K2Cr2O7 was good, which confirms the suitability of this assay for conventional chemicals. However, the variability of AgNPs toxicity results was very high showing again that nanomaterials are inherently challenging for toxicity studies, especially those which toxic effect is linked to shed metal ions. Among the identified sources for this variability were: the hatching conditions, the type of test plate incubation and the illumination regime. The latter induced variations assumingly due to the changes in bioavailable silver species concentrations. Up to our knowledge this is the first inter-laboratory comparison of the Artemia sp. toxicity study involving nanomaterials. Although the inter-laboratory exercise revealed poor repeatability of AgNPs toxicity results, this study provides valuable information regarding the importance of harmonisation of all steps in the test procedure. Also, the presented AgNPs toxicity case study may serve as a platform for further validation steps with other types of NMs., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Biomolecular profiling with Fourier-Transform InfraRed Microscopy was performed to distinguish the Zn(2+)-mediated effects on the crustacean (Porcellio scaber) digestive glands from the ones elicited by the ZnO nanoparticles (NPs). The exposure to ZnO NPs or ZnCl2 (1500 and 4000 µg Zn/g of dry food) activated different types of metabolic pathways: some were found in the case of both substances, some only in the case of ZnCl2, and some only upon exposure to ZnO NPs. Both the ZnO NPs and the ZnCl2 increased the protein (∼1312 cm(-1); 1720-1485 cm(-1)/3000-2830 cm(-1)) and RNA concentration (∼1115 cm(-1)). At the highest exposure concentration of ZnCl2, where the effects occurred also at the organismal level, some additional changes were found that were not detected upon the ZnO NP exposure. These included changed carbohydrate (most likely glycogen) concentrations (∼1043 cm(-1)) and the desaturation of cell membrane lipids (∼3014 cm(-1)). The activation of novel metabolic pathways, as evidenced by changed proteins' structure (at 1274 cm(-1)), was found only in the case of ZnO NPs. This proves that Zn(2+) are not the only inducers of the response to ZnO NPs. Low bioavailable fraction of Zn(2+) in the digestive glands exposed to ZnO NPs further supports the role of particles in the ZnO NP-generated effects. This study provides the evidence that ZnO NPs induce their own metabolic responses in the subtoxic range.