Overview
ISO/TS 23034:2021 - Nanotechnologies specifies a near‑infrared (NIR) optical absorption method to estimate the in vitro cellular uptake of carbon nanomaterials (CNMs). The technique measures absorbance of cell lysates to detect CNMs that are internalized or tightly adhered to the cell membrane from liquid dispersions. ISO/TS 23034:2021 is intended as a simple, rapid screening method; additional techniques may be required when absolute quantification is needed.
Key topics and technical requirements
- Principle: Uses NIR optical absorption (typically 700–900 nm) where cellular biomolecule absorption is low, so CNM absorbance dominates. Absorbance is proportional to CNM concentration (A = k · t · c) when wavelength and path length are fixed.
- Applicable materials: Carbon nanotubes (SWCNT, MWCNT), carbon nanohorns (CNHs), carbon black, graphene - CNMs that show broad vis–NIR absorbance. Not suitable for CNMs lacking NIR absorption (e.g., some nanodiamonds).
- Apparatus: UV‑Vis‑NIR spectrometer, cuvettes (defined optical pathlength), incubator (37 °C, 5% CO2), centrifuge, homogenizer, cell counter, multi‑well culture plates.
- Procedure elements:
- Preparation of CNM dispersions and calibration curves from known concentrations.
- Cell seeding, exposure to CNM suspensions, washing, and controlled cell lysis.
- Measurement of cell lysate absorbance in the NIR window and data analysis to estimate uptake per cell or per well.
- Data quality & variability: Guidance on sources of variability, case studies (SWCNTs, CNHs, MWCNTs), and recommendations for reporting and data sheet formats.
- References: Normative references include ISO 3696 (water for analytical use) and ISO/TS 80004‑3 (nanotechnologies - vocabulary for carbon nano‑objects).
Applications and users
- Who uses it: Nanomaterial researchers, toxicologists, academic labs, industrial R&D (nanobiotechnology, drug delivery), regulatory and safety assessment laboratories.
- Practical uses:
- Rapid in vitro screening of CNM cellular association and uptake.
- Comparative uptake studies across CNM types, dispersants, or cell lines.
- Early toxicological screening to prioritize materials for more detailed quantitative analyses (e.g., fluorescence, radioisotope tracing, TEM).
- Quality control and method development where NIR absorbance provides a simple assay readout.
Related standards
- ISO/TS 80004‑3 - Nanotechnologies: vocabulary - Part 3: Carbon nano‑objects.
- ISO 3696 - Water for analytical laboratory use - specification and test methods.
Keywords: ISO/TS 23034:2021, nanotechnologies, carbon nanomaterials, cellular uptake, optical absorption, near‑infrared, UV‑Vis‑NIR spectrometer, in vitro screening.