The project aims at three objectives:
- Identification of structure-activity relationships between specific characteristics of nanoparticles and their biological activity
- Analysis of fate, behaviour and effects of silver species originating from consumer products
- Hazard and risk assessment of nanomaterials
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1.1 Manufacture and chemical characterization of Ag-NP
This task comprises the synthesis of silver based reference materials for elucidating basic mechanisms and modes of action. Two basically different kinds of Ag-NPs which are already in use will be included:
Composite particles with silver doted on a supporting matrix of metal oxide (Ag/TiO 2 -NP) and pure silver nanoparticles (Ag-NP). The characterization will be performed with respect to structural aspects of powdered Ag-NP and on dissolved Ag-NP with regard to their colloidal stability.
The behaviour of silver based NP is mainly determined by surface modifications (lipophilic, hydrophilic).
Therefore, Ag-NP with fluorescent surface marker molecules will be synthesized to study their characteristics after surface modifications by functional groups. This allows for monitoring the cellular uptake by fluorescence microscopy.
Continuous analytical monitoring will ensure stable particle suspensions in reproducible quality.
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1.2 Behaviour and effects of Ag-NPs with specific characteristic
The prerequisite for the studies on the behaviour and effects of Ag-NP with specific characteristics is the development of a standard operation procedure (SOP) for the production and handling of defined suspensions. The SOP focuses on the dispersion and stabilisation of the Ag-NPs in different aqueous phases. The SOP will be transferred to all partner laboratories to provide standardised assays and hence comparable conditions.
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The accompanying analytics focuses on the following problems:
- Characterisation of the NP in the test medium before application on biological test system
- Characterisation of the NP after contact with biological systems
- Development of appropriate methods to detect and characterise NPs from complex environmental compartments (i.e. sewage sludge, waste water, soil)
These aspects are of central interest, because only the precise characterisation of the different species of NPs allows for the interpretation of results from screening tests as well as the behaviour in waste water and the effects on aquatic and terrestrial systems.
A further main focus includes the elucidation of basic mechanisms of the effects of Ag-NPs at the sub-cellular and cellular level. This work package combines different biochemical and biological in vitro test systems as well as fluorescent NPs in order to get more information on the biological states (morphological, physiological or biochemical) which lead to high or low sensitivity towards Ag-NPs.
One further aim is to get basic information which specific characteristics of AG-NPs influence their behaviour in pore water and in waste water.
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2.1 Simulation of relevant scenarios: fate and behaviour of Ag-NPs
Fundamental differences of Ag-NPs containing consumer products can be attributed to the influence of the bulk textile material, auxiliary materials and the use of the textiles. Thus, in this work package textiles will be studied in terms of:
- The antimicrobial activity
- The abrasion of Ag-NPs and their further dispersion into air and airborne dust
- The abrasion and discharge into waste water streams and sewage treatment plants
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2.2 Characterisation of exposure
The data about the fate and behaviour of Ag-NPs from textiles will be assessed qualitatively. Airborne dust and waste water will be studied to determine the accumulation of different fractions or size distributions and higher aggregates of Ag-NPs.
Furthermore,
Ag+ incorporation into sewage sludge and soil will be characterised with regard to its short-, middle- and long-term mobility. The experimental data will result in the configuration of an integrated mathematical model of the behaviour of Ag-NP for a generalised risk assessment. |
2.3 Characterisation of biological effects
The effects of Ag-NPs on terrestrial organisms at different tropical levels will be studied as well as the bioaccumulation potential of the nanomaterials. Standard operation procedures and their modifications will be developed and applied. The participating project partners will coordinate their tasks in order to cover a wide range of soil characteristics.
The effects of Ag-NPs on aquatic organisms of varying tropic levels will be studied using standard test protocols for the testing of chemicals, OECD test guidelines, OECD draft guidelines and ISO-norms. Modifications of the test systems may be reasonable for the application and exposure of Ag-NPs. All tests will be accompanied by a sound continuous analytical setup. This work package will provide information on the applicability and/or the need for modifications of standard operation procedures for the study of nanomaterials as well as on the influence of different growth media on effects, aggregation and bioavailability of Ag-NPs.
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3.1 Life cycle analysis
In this topic, the potential exposure of man and the environment to different silver species (Ag-NP, silver particles >100nm; dissolved Ag+; bound silver particles) will be identified along the textile chain as an examplary technological application of silver nanomaterials. All stations of the textile chain from the initial production of textile fibres to abrasion of particles during use and discharge into waste and washing water up to the final disposal will be considered. Particular attention will be payed to:
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3.2 Hazard and risk assessment
The final hazard and risk assessment will be based on the life cycle analysis and the experimentally established data according to the “Guidance for the Implementation of REACh”. Actual information concerning nanomaterials within REACh (results from the “CASG Subgroup on Nanomaterials”) as well as the expertise of the UBA will be taken into account.
The results will provide essential knowledge for the regulatory handling of nanomaterials. New methodologically sound approaches will be incorporated into the European (EC and ECHA) and into international (OECD- WPMN, -WNT, CEN und ISO) guidelines.
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