Overview
ISO/TR 23652:2024 - Nanotechnologies - Considerations for radioisotope labelling methods of nanomaterials for performance evaluation is a Technical Report from ISO/TC 229 that reviews radioisotope labelling approaches for nanomaterials used in biodistribution and performance studies. The document summarizes labelling strategies, discusses advantages and disadvantages of each method, and provides guidance on selecting a matched pair of nanomaterial and radioisotope labelling method to ensure the in vivo integrity and performance stability of radio-labelled nanomaterials.
Key topics and technical requirements
- Scope and purpose: review of labelling methods, comparative assessment, and criteria for selecting matched pairs to avoid dissociation of radiolabel from the nanomaterial in vivo.
- Biodistribution study methods: image-based (PET, SPECT), tissue radioactivity measurement, and autoradiography - including considerations for administration routes (intravenous, inhalation, oral, intraperitoneal, etc.).
- Radioisotope fundamentals: diagnostic vs therapeutic isotopes (diagnostic isotopes are commonly used for biodistribution because of lower toxicity and better penetration), and optimal gamma energies for imaging.
- Labelling methods reviewed:
- Pre- and post-surface labelling
- Chelating agent-based labelling (use of bifunctional chelators)
- Chelating agent-free methods: radioactive/non-radioactive precursors, specific trapping, cation exchange, neutron/proton beam activation
- Dual radioisotope labelling for complex tracing needs
- Production routes: cyclotron-produced, reactor-produced, and generator-produced radioisotopes - and practical implications for availability and specific activity.
- Stability and matched-pair selection: guidance to ensure the radiolabel remains associated with the nanomaterial during in vivo studies to prevent misleading biodistribution data.
- Annexes: representative radioisotopes (Annex A) and a tabulated analysis of advantages/disadvantages of labelling methods (Annex B).
- Normative references: links to ISO 80004-1 and ISO/TS 80004-8 for nanotechnology vocabulary.
Practical applications and target users
Who benefits from ISO/TR 23652:2024:
- Nanomedicine developers and formulation scientists performing preclinical biodistribution and ADME studies.
- Radiochemists and radiopharmacists selecting labelling strategies and isotopes.
- Preclinical imaging specialists using PET, SPECT, or autoradiography to quantify nanomaterial distribution.
- Toxicologists and pharmacokineticists evaluating in vivo behaviour and safety of nanoparticle-based therapeutics.
- Regulatory reviewers and quality assurance teams assessing study design and data integrity for clinical translation.
Typical use cases:
- Designing robust biodistribution studies that avoid radiolabel detachment.
- Selecting appropriate chelators or chelator-free methods matched to the nanomaterial chemistry.
- Choosing isotope production routes and isotopes compatible with imaging modality and study timing.
Related standards
Keywords: ISO/TR 23652:2024, radioisotope labelling, nanomaterials, biodistribution, chelating agent, chelator-free labelling, PET, SPECT, nanoparticle stability, matched pair selection.