Overview
ISO/TS 23459:2021 provides standardized measurement protocols to assess protein secondary structure changes that occur when proteins interact with nanomaterials using ultraviolet circular dichroism (UV‑CD) spectroscopy. The technical specification defines test conditions, sample preparation, instrumental settings and data analysis workflows to detect alterations in α‑helix, β‑sheet and other secondary structure elements. Note: this document does not apply to intrinsically disordered proteins.
Keywords: ISO/TS 23459:2021, UV‑CD, ultraviolet circular dichroism, protein secondary structure, nanomaterials, nanoparticle, protein–nanomaterial interactions.
Key topics and technical requirements
- Scope & exclusions: Focused on secondary structure changes induced by nanomaterial–protein interactions; excludes characterization of disordered proteins.
- Instrumentation: UV‑CD spectrometer with data range typically from 175 nm to 700 nm and temperature control.
- Sample cells: Use highly transparent, non‑optically active quartz cells (rectangular or cylindrical) with path lengths 0.5 mm to 10.0 mm; thorough cleaning between runs is required.
- Sample preparation:
- Prepare protein stock solutions (recommended 1.0–5.0 mg/ml) in appropriate low‑absorption buffers.
- Working concentrations for UV‑CD measurements typically 0.005–5.0 mg/ml, adjusted by path length and buffer.
- Use low‑binding labware and deionized water; avoid optically active buffers.
- Measurement procedures: Guidance on buffer selection, stability assessment of nanoparticle (NP) suspensions in protein solutions, and stepwise UV‑CD recording protocols.
- Data processing: Calculation of molar ellipticity (mean residue ellipticity) and standardized data‑analysis methods to estimate secondary structure fractions.
- Reporting: Required elements for a reproducible test report, plus informative annexes with typical spectra, buffer lists, unit conversions, concentration calculations and secondary‑structure estimation methods.
Applications and who should use it
- Researchers studying nanomaterial–protein interactions, protein corona formation and nanoparticle bio‑reactivity.
- Analytical and biophysical labs using CD spectroscopy for protein structural assessment in nanotoxicology, nanomedicine, formulation development and materials research.
- Quality control and regulatory testing where standardized, reproducible methods for assessing protein conformational change are required.
- Contract research organizations (CROs), pharmaceutical developers, academic groups and standards bodies.
Keywords: protein corona, nanotoxicology, CD spectroscopy, nanoparticle characterization, mean residue ellipticity.
Related standards
- ISO/TS 80004 series (vocabulary for nanotechnologies): ISO/TS 80004‑1, ‑2, ‑4, ‑6 - referenced for terms such as nanoparticle and nanomaterial.