The EU Chemicals Strategy for Sustainability is a first step to achieve the Green Deal ambition for a toxic-free environment, and ensure that chemicals are produced and used in a way that maximises... Show moreThe EU Chemicals Strategy for Sustainability is a first step to achieve the Green Deal ambition for a toxic-free environment, and ensure that chemicals are produced and used in a way that maximises their contribution to society while avoiding harm to our planet and to future generations. Advanced materials are predicted to play a pivotal role in achieving this ambition and the underlying sustainability goals, and considerable efforts are invested in designing new classes of materials. Examples of such materials are metamaterials, artificially architectured materials designed to have material properties beyond those of the individual ingredient materials, or active materials at the boundary between materials and devices (e.g., new biomedical soft materials). Such innovative advanced materials raise concern about possible future safety and sustainability issues and would benefit from appropriate risk governance that promotes innovation, while pushing for safety and sustainability. To balance these aspects, a methodology is proposed for the early-stage identification of emerging safety and sustainability issues of advanced materials. As exemplified by two case studies, the methodology aims to be of use for innovators, risk assessors, and regulators. Extension of the methodology is highlighted, as well as implementation in broader initiatives like the EU's industrial policy approach. Show less
Dalen, F.J. van; Bakkum, T.; Leeuwen, T. van; Groenewold, M.; Deu, E.; Koster, A.J.; ... ; Verdoes, M. 2021
Cathepsin S is a lysosomal cysteine protease highly expressed in immune cells such as dendritic cells, B cells and macrophages. Its functions include extracellular matrix breakdown and cleavage of... Show moreCathepsin S is a lysosomal cysteine protease highly expressed in immune cells such as dendritic cells, B cells and macrophages. Its functions include extracellular matrix breakdown and cleavage of cell adhesion molecules to facilitate immune cell motility, as well as cleavage of the invariant chain during maturation of major histocompatibility complex II. The identification of these diverse specific functions has brought the challenge of delineating cathepsin S activity with great spatial precision, relative to related enzymes and substrates. Here, the development of a potent and highly selective two-step activity-based probe for cathepsin S and the application in multicolor bio-orthogonal correlative light-electron microscopy is presented. LHVS, which has been reported as a selective inhibitor of cathepsin S with nanomolar potency, formed the basis for our probe design. However, in competitive activity-based protein profiling experiments LHVS showed significant cross-reactivity toward Cat L. Introduction of an azide group in the P2 position expanded the selectivity window for cathepsin S, but rendered the probe undetectable, as demonstrated in bio-orthogonal competitive activity-based protein profiling. Incorporation of an additional azide handle for click chemistry on the solvent-exposed P1 position allowed for selective labeling of cathepsin S. This highlights the influence of click handle positioning on probe efficacy. This probe was utilized in multicolor bio-orthogonal confocal and correlative light-electron microscopy to investigate the localization of cathepsin S activity at an ultrastructural level in bone marrow-derived dendritic cells. The tools developed in this study will aid the characterization of the variety of functions of cathepsin S throughout biology. Show less
Bakkum, T.; Heemskerk, M.T.; Bos, E.; Groenewold, M.; Oikonomeas-Koppasis, N.; Walburg, K.V.; ... ; Kasteren, S.I. van 2020
Bioorthogonal correlative light-electron microscopy (BCLEM) can give a detailed overview of multicomponent biological systems. It can provide information on the ultrastructural context of... Show moreBioorthogonal correlative light-electron microscopy (BCLEM) can give a detailed overview of multicomponent biological systems. It can provide information on the ultrastructural context of bioorthogonal handles and other fluorescent signals, as well as information about subcellular organization. We have here applied B-CLEM to the study of the intracellular pathogen Mycobacterium tuberculosis (Mtb) by generating a triply labeled Mtb through combined metabolic labeling of the cell wall and the proteome of a DsRed-expressing Mtb strain. Study of this pathogen in a B-CLEM setting was used to provide information about the intracellular distribution of the pathogen, as well as its in situ response to various clinical antibiotics, supported by flow cytometric analysis of the bacteria, after recovery from the host cell (ex cellula). The RNA polymerase-targeting drug rifampicin displayed the most prominent effect on subcellular distribution, suggesting the most direct effect on pathogenicity and/or viability, while the cell wall synthesis-targeting drugs isoniazid and ethambutol effectively rescued bacterial division-induced loss of metabolic labels. The three drugs combined did not give a more pronounced effect but rather an intermediate response, whereas gentamicin displayed a surprisingly strong additive effect on subcellular distribution. Show less
Oomen, A.G.; Bleeker, E.A.J.; Bos, P.M.J.; Broekhuizen, F. van; Gottardo, S.; Groenewold, M.; ... ; Landsiedel, R. 2015
Physicochemical properties of chemicals affect their exposure, toxicokinetics/fateand hazard, and for nanomaterials, the variation of these properties results in a wide variety ofmaterials with... Show morePhysicochemical properties of chemicals affect their exposure, toxicokinetics/fateand hazard, and for nanomaterials, the variation of these properties results in a wide variety ofmaterials with potentially different risks. To limit the amount of testing for risk assessment,the information gathering process for nanomaterials needs to be efficient. At the same time,sufficient information to assess the safety of human health and the environment should beavailable for each nanomaterial. Grouping and read-across approaches can be utilised tomeet these goals. This article presents different possible applications of grouping andread-across for nanomaterials within the broader perspective of the MARINA RiskAssessment Strategy (RAS), as developed in the EU FP7 project MARINA. Firstly,nanomaterials can be grouped based on limited variation in physicochemical properties tosubsequently design an efficient testing strategy that covers the entire group. Secondly,knowledge about exposure, toxicokinetics/fate or hazard, for example via properties suchas dissolution rate, aspect ratio, chemical (non-)activity, can be used to organise similarmaterials in generic groups to frame issues that need further attention, or potentially toread-across. Thirdly, when data related to specific endpoints is required, read-across can beconsidered, using data from a source material for the target nanomaterial. Read-acrosscould be based on a scientifically sound justification that exposure, distribution to thetarget (fate/toxicokinetics) and hazard of the target material are similar to, or less than, thesource material. These grouping and read-across approaches pave the way for better use ofavailable information on nanomaterials and are flexible enough to allow future adaptationsrelated to scientific developments. Show less
