Overview
ISO/TR 22455:2021 - Nanotechnologies: High throughput screening method for nanoparticles toxicity using 3D model cells describes a laboratory method for high-throughput evaluation of cytotoxic responses of three-dimensional (3D) cell models exposed to nanoparticles (NPs) while minimizing optical interference. The technical report targets biological testing laboratories experienced in cell culture and nanoparticle cytotoxicity assessment, and applies to nano-objects including nanoparticles, nanopowders, nanofibres, nanotubes, nanowires, and their aggregates/agglomerates.
Key topics and requirements
- Purpose: Provide a reproducible high-throughput screening (HTS) approach for NP toxicity that reduces false results caused by NP optical properties (absorbance, photoluminescence) and reagent–NP interactions.
- Assay platform: Uses 3D-model cells cultured on a pillar insert / micropillar chip, enabling transfer of cell-containing hydrogel droplets between wells to expose cells to fresh viability reagents without optical interference from suspended NPs.
- Coverage: Applies to a wide range of nano-objects and secondary particles (agglomerates/aggregates).
- Methods and steps included:
- Cell culture and generation of 3D-model cells (encapsulation on micropillar chips).
- Preparation of the pillar insert and handling for automated/miniaturized testing.
- Nanoparticle sample preparation and exposure procedures.
- Cell viability analysis workflows, including WST assays (colorimetric) and live‑cell imaging alternatives.
- Controls and interference considerations: Discusses the effects of NP optical properties on common assays (WST-1, WST-8, XTT, MTS, MTT, luminescence ATP assays) and recommends procedures to reduce assay artefacts.
- Terminology: References ISO/TS 80004-2 for nano-object definitions.
Applications and users
ISO/TR 22455:2021 is practical for:
- Toxicologists and in vitro assay developers validating NP safety.
- Nanomaterials manufacturers and R&D teams performing hazard screening.
- Contract research organizations (CROs) and academic labs conducting high-throughput nanoparticle cytotoxicity screens.
- Regulatory scientists and safety assessors seeking standardized HTS protocols that account for NP-specific assay interference.
Benefits:
- More reliable, reproducible cell viability data for nano-enabled products.
- Reduced false positives/negatives from NP optical absorbance or luminescence quenching.
- Compatibility with automated HTS workflows (e.g., 96‑well plates or microchip formats).
Related standards
- ISO/TS 80004-2 - Nanotechnologies - Vocabulary (Nano-objects): referenced for terms and definitions relevant to nano‑objects and nanoparticles.
Keywords: ISO/TR 22455:2021, nanotechnologies, high throughput screening, 3D model cells, nanoparticles toxicity, cell viability assays, optical interference, pillar insert, WST assay, live-cell imaging, nanopowders, nanofibres, nanotubes, nanotools.