Overview
ISO 19337:2023 - Nanotechnologies: Characteristics of working suspensions of nano-objects for in vitro assays to evaluate inherent nano-object toxicity - defines the essential characterization and measurement requirements for working suspensions used in cell‑based (in vitro) toxicity testing. Applicable to nano‑objects and their aggregates/agglomerates greater than 100 nm, the standard helps distinguish true nano‑object toxicity from artefacts caused by suspension instability, ionic dissolution, corona formation or contamination.
Key Topics and Requirements
- Scope and purpose
- Characterize working suspensions prepared for in vitro assays and identify applicable measurement methods.
- Enable clear interpretation of whether observed effects arise from the nano‑objects themselves or uncontrolled sources.
- Essential characteristics to measure
- Stability of working suspensions - representative size change of secondary particles (aggregation/agglomeration) and concentration change (sedimentation/gravitational settling). Results should be expressed as percent change over the assay timescale.
- Concentration of metal ions - measure ionic dissolution after separating particulates (U/F, centrifugation, C‑U/F, TFF).
- Concentration of culture medium components - e.g., proteins, calcium, and other medium constituents that affect corona formation and assay outcomes.
- Contamination - trace extrinsic substances (including biological contaminants) that can affect cellular responses.
- Measurement methods (examples listed in the standard)
- Size and stability: DLS (dynamic light scattering), LD (laser diffraction), SLS (static light scattering).
- Concentration and composition: ICP‑MS, ICP‑AES, AAS, UV‑Vis, X‑ray transmission, TOC analysis.
- Separation techniques: ultrafiltration (U/F), centrifugation, tangential flow filtration (TFF).
- Procedural expectations
- Prepare separate aliquots for toxicity assays and characterization.
- Perform measurements for each dose and report results (units: molarity, mass/mass, or mass/volume for ions).
- Follow the flow of measurements (Annex A is normative in the 2023 edition); Annexes B–E provide informative measurement guidance.
Applications and Who Uses It
- Research laboratories and toxicologists conducting reliable in vitro nano‑toxicity screening.
- Nanomaterial manufacturers and quality assurance teams validating product safety and batch consistency.
- Regulators and risk assessors evaluating submitted toxicity data for decision‑making.
- Contract research organizations (CROs) that perform standardized in vitro testing for clients.
ISO 19337:2023 supports reproducible, interpretable in vitro results by standardizing suspension characterization - critical for safe product development, regulatory compliance, and scientific communication.
Related Standards
- ISO/TS 80004‑2 - Nanotechnologies - Vocabulary - Part 2: Nano‑objects (referenced for terminology).
- ISO/TR 13097 - Recommended guidance for suspension stability (cited as a practical reference).
- Note: ISO 19337:2023 is the second edition, replacing ISO/TS 19337:2016; Annex A’s status was updated to normative.