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ISO/TS 27687:2008 — Nanotechnologies — Terminology and definitions for nano-objects — Nanoparticle, nanofibre and nanoplate
ISO/TS 27687:2008 | Nanotechnology Terminology Standard
Introduction to ISO/TS 27687:2008
ISO/TS 27687:2008, “Nanotechnologies — Terminology and definitions for nano-objects — Nanoparticle, nanofibre and nanoplate,” provides the foundational vocabulary for the field of nanotechnology. Published as a Technical Specification, it establishes unambiguous definitions for core nano-object classifications that underpin research, commercialization, and regulatory frameworks worldwide. The document was later revised and incorporated into ISO/TS 80004-2, but its original classification schema remains the de facto reference for nanotechnology terminology in academic publications, patent applications, and regulatory submissions. The standard was developed by ISO/TC 229 (Nanotechnologies) and represents a critical early effort to bring terminological order to a rapidly evolving scientific field where inconsistent language was impeding progress.
When writing scientific manuscripts or patent applications involving nanomaterials, always reference ISO/TS 27687:2008 definitions to ensure your claims are interpreted with the correct size and morphology constraints. Patent examiners increasingly rely on these standardized definitions when evaluating novelty and inventive step.
The specification defines a hierarchical terminology system beginning with the broad term “nano-object” — a material with one, two, or three external dimensions in the size range from approximately 1 nm to 100 nm. Below this umbrella term, the specification systematically classifies nano-objects by their number of nanoscale dimensions: nanoparticles (three external nanoscale dimensions), nanofibers (two external nanoscale dimensions), and nanoplates (one external nanoscale dimension). Each category is further subdivided by morphology, aspect ratio, and internal structure. For instance, nanofibers are divided into nanotubes (hollow),nanorods (solid, aspect ratio 3-20), and nanowires (solid, electrically conductive). This hierarchical approach is essential because the physical properties and biological interactions of nanomaterials are governed as much by their shape as by their chemical composition.
The scope of the specification extends beyond simple definitions to include guidance on how to apply the terminology in different contexts. It provides decision trees for classifying unknown nano-objects based on microscopy or scattering data, rules for naming composite or coated nano-objects, and conventions for reporting size distributions that account for the polydispersity inherent in nanomaterial samples. These practical elements make the standard useful not only for lexicographers but also for laboratory scientists and quality control engineers who need to apply the terminology correctly in their daily work.
Core Terminology and Classification Hierarchy
The classification hierarchy established by ISO/TS 27687:2008 is critical because the physical, chemical, and biological properties of nanomaterials are strongly dependent on their shape and size distribution. For example, the toxicological profile of a nanoparticle differs markedly from that of a nanofiber of the same material composition, due to differences in surface area-to-volume ratio, cellular uptake mechanisms, and clearance pathways. The aspect ratio (length divided by width) is particularly important for nanofibers — materials with aspect ratios above 100:1, such as certain multi-walled carbon nanotubes, behave very differently in biological systems than those with lower aspect ratios.
| Term | Definition | Nanoscale Dimensions | Example Applications |
|---|---|---|---|
| Nano-object | Material with one or more external dimensions in the nanoscale (1 nm to 100 nm) | 1, 2, or 3 | Parent category for all nanoscale entities |
| Nanoparticle | Nano-object with all three external dimensions in the nanoscale | 3 | Drug delivery vehicles, quantum dots for displays, catalytic nanoparticles |
| Nanofibre | Nano-object with two external dimensions in the nanoscale | 2 | Carbon nanotube composites, cellulose nanofibrils for packaging |
| Nanoplate | Nano-object with one external dimension in the nanoscale | 1 | Graphene electronics, clay nanoplates for barrier films |
| Nanotube | Hollow nanofibre with open or closed ends | 2 | Single-wall and multi-wall carbon nanotubes, boron nitride nanotubes |
| Nanowire | Electrically conducting nanofibre | 2 | Silver nanowire transparent electrodes, silicon nanowire sensors |
| Nanopore | Pore with nanoscale dimensions | N/A | DNA sequencing membranes, molecular sieves |
| Nanostructured material | Material with internal or surface nanostructure | Varies | Nanocrystalline metals, photonic crystals |
A common terminological error is using “nanoparticle” as a synonym for all nano-objects. ISO/TS 27687:2008 explicitly restricts “nanoparticle” to objects with three nanoscale dimensions. A graphene sheet is a nanoplate, not a nanoparticle — using the wrong term can lead to regulatory confusion and scientific miscommunication, particularly in safety data sheet preparation.
Impact on Metrology and Regulation
The precise definitions in ISO/TS 27687:2008 have far-reaching implications beyond academic taxonomy. In regulatory contexts — such as the EU’s REACH regulations for chemical registration, the FDA’s guidance on nanomaterial-containing products, and the OECD’s testing guidelines for manufactured nanomaterials — the definitions determine which materials fall under regulatory scrutiny and what testing protocols apply. A material classified as a nanoparticle may require different ecotoxicity testing than one classified as a nanofibre, even if both are composed of the same base substance. The European Commission’s 2011 Recommendation on the definition of nanomaterials explicitly references the ISO/TS 27687 framework, and subsequent regulatory developments in the EU, US, and other jurisdictions continue to build upon its classification principles.
From a metrology perspective, the specification’s requirement that dimensions be measured in the range of 1 nm to 100 nm imposes stringent demands on measurement instrumentation. Techniques such as transmission electron microscopy (TEM), scanning electron microscopy (SEM), dynamic light scattering (DLS), and atomic force microscopy (AFM) must be carefully calibrated and cross-validated to ensure that reported dimensions are accurate and traceable to international measurement standards. The specification also emphasizes that agglomeration and aggregation states must be reported alongside primary particle dimensions, as these dramatically affect the effective size distribution and, consequently, the correct terminological classification. A material that is nanoparticle-grade in its primary form may behave as a microparticle in its agglomerated state — both dimensions should be reported following the standard’s conventions.
The hierarchical terminological framework of ISO/TS 27687:2008 has been adopted by over 40 national standards bodies and serves as the basis for the OECD’s Working Party on Manufactured Nanomaterials (WPMN) testing program, which has published over 100 testing guidelines referencing these definitions.
Ignoring the aspect-ratio-based classification can have safety consequences. High-aspect-ratio nanofibres (such as certain carbon nanotubes with aspect ratios exceeding 250:1) have been shown to exhibit asbestos-like pathogenicity when inhaled, while low-aspect-ratio nanoparticles of the same material may not. The terminology framework directly supports hazard classification and risk communication.
Frequently Asked Questions
Q1: What is the lower size limit for nano-objects under ISO/TS 27687:2008?
A: The specification states “approximately 1 nm” as the lower bound. Below 1 nm, materials are typically considered molecular or atomic clusters rather than nano-objects, though the exact cutoff depends on the property of interest. For example, fullerenes (approximately 0.7 nm diameter) are often considered nano-objects in practice despite falling below the 1 nm guideline.
A: The specification states “approximately 1 nm” as the lower bound. Below 1 nm, materials are typically considered molecular or atomic clusters rather than nano-objects, though the exact cutoff depends on the property of interest. For example, fullerenes (approximately 0.7 nm diameter) are often considered nano-objects in practice despite falling below the 1 nm guideline.
Q2: How does ISO/TS 27687:2008 relate to ISO/TS 80004 series?
A: ISO/TS 27687:2008 was a precursor to the ISO/TS 80004 family. The core definitions from 27687 were incorporated into ISO/TS 80004-2:2015, which extends the terminology to include additional nanostructured and nanomanufacturing terms. ISO/TS 80004 now serves as the comprehensive terminology reference, but 27687 remains historically important.
A: ISO/TS 27687:2008 was a precursor to the ISO/TS 80004 family. The core definitions from 27687 were incorporated into ISO/TS 80004-2:2015, which extends the terminology to include additional nanostructured and nanomanufacturing terms. ISO/TS 80004 now serves as the comprehensive terminology reference, but 27687 remains historically important.
Q3: Are nano-objects always 1-100 nm in all dimensions?
A: No. Only nanoparticles have all three dimensions in the nanoscale. Nanofibres have two nanoscale dimensions, and nanoplates have one. As long as at least one dimension is in the 1-100 nm range, the material qualifies as a nano-object. This distinction is critical for accurate classification.
A: No. Only nanoparticles have all three dimensions in the nanoscale. Nanofibres have two nanoscale dimensions, and nanoplates have one. As long as at least one dimension is in the 1-100 nm range, the material qualifies as a nano-object. This distinction is critical for accurate classification.
Q4: Does the standard cover engineered nanomaterials only, or incidental nanomaterials too?
A: The definitions in ISO/TS 27687:2008 are morphology-based and do not distinguish between engineered, incidental, and natural nano-objects. However, subsequent ISO standards (e.g., ISO/TS 80004-1) introduce distinctions based on intentionality of manufacture. For regulatory reporting, both the morphology classification and the origin classification are typically required.
A: The definitions in ISO/TS 27687:2008 are morphology-based and do not distinguish between engineered, incidental, and natural nano-objects. However, subsequent ISO standards (e.g., ISO/TS 80004-1) introduce distinctions based on intentionality of manufacture. For regulatory reporting, both the morphology classification and the origin classification are typically required.
