Overview
ISO 29701:2010 - Nanotechnologies - Endotoxin test on nanomaterial samples for in vitro systems - Limulus amebocyte lysate (LAL) test - specifies how to apply the Limulus amebocyte lysate (LAL) reagent to detect and quantify bacterial endotoxin (lipopolysaccharide, LPS) in nanomaterial samples intended for cell‑based in vitro biological tests. The standard covers aqueous dispersions and aqueous extracts (e.g., water, serum or reaction medium incubated with nanomaterials at 37 °C) and provides guidance to reduce confounding endotoxin contamination in nanotoxicology and biocompatibility studies. Methods can also be adapted for nanomaterials intended for parenteral animal administration.
Key technical topics and requirements
- Test scope: Applies to nanomaterials dispersed in aqueous media or to media incubated with nanomaterials; restricted to in vitro test samples (adaptable to parenteral routes).
- Pre-test controls: Recommendations for endotoxin‑free storage, sealable containers (glass or heat‑treated ware), and avoidance of environmental dust and tap water contamination.
- Storage and handling: Heat treatment examples for containers (>250 °C for ≥30 min or validated alternatives); store test samples at 2–8 °C and test promptly.
- Test sample types and preparation:
- Aqueous dispersions (direct testing or dilution).
- Aqueous extracts using endotoxin‑free media; centrifugation to remove particulates; extraction conditions justified and recorded.
- Dispersion techniques include hand grinding, mechanical milling, ultrasonication.
- Test methods: Covers LAL assay formats including gel‑clot, photometric/chromogenic (endpoint), and kinetic/turbidimetric approaches (Annexes B–D). Defines key terms (EU - endotoxin unit, λ - sensitivity).
- Interference and validation: Guidance on inhibition/enhancement (I/EC) controls, validation of extraction and test methods, and checking for matrix or nanoparticle interference (e.g., plastics or surfactants).
- Reporting and interpretation: Includes assessment of results and documentation requirements to support in vitro toxicology conclusions.
Practical applications and users
- Who uses it: Nanotoxicologists, in vitro assay labs, material scientists, regulatory and quality control teams, medical device and nanomaterial manufacturers.
- Why use it:
- Ensure endotoxin levels do not confound cell‑based toxicity and immunological responses.
- Provide validated endotoxin data to support biocompatibility, safety screening, and regulatory submissions.
- Standardize sample preparation and LAL testing for reproducible results across laboratories.
Related standards and references
- ISO 10993‑12:2007 (extraction methods for biological evaluation)
- ISO 14644‑1 (cleanroom air cleanliness classes) - referenced for laboratory environment guidance
- Pharmacopoeial bacterial endotoxin tests and WHO reference standard endotoxin (RSE) for unit definitions
Keywords: ISO 29701:2010, LAL test, endotoxin testing, nanomaterials, in vitro, Limulus amebocyte lysate, nanotechnologies, endotoxin units, gel‑clot, chromogenic, kinetic.
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