Quick Definition
What is Gamma Sterilisation in Bioprocessing?: Gamma sterilisation is the process of exposing single-use bioprocessing bags to ionising gamma radiation from a Co-60 source to achieve a sterility assurance level (SAL) of 10⁻⁶ — meaning the probability of a single viable microorganism surviving is less than 1 in 1,000,000. It is the standard sterilisation method for single-use bags in biopharmaceutical manufacturing.
ISO 11137 — sterilisation validation
ISO 11137 defines validation and routine control of radiation sterilisation. For single-use bags, it establishes: the minimum dose for SAL 10⁻⁶ based on product bioburden; dose mapping to confirm uniform distribution throughout the product; and ongoing dosimetry monitoring to confirm each cycle delivers the validated dose.
Gamma vs ETO vs steam
Gamma sterilisation is preferred because it penetrates the bag in final packaging without disassembly; leaves no chemical residues (unlike ETO); and can be performed at room temperature (unlike steam, which damages polyethylene films). ETO requires outgassing time and residual monitoring. Steam (autoclave) is not suitable for single-use bag films.
Key Facts
- Standard dose: 25 kGy minimum — validated per ISO 11137 to achieve SAL 10⁻⁶
- Damages DNA of microorganisms (bacteria, spores, fungi, viruses) — prevents replication and kills organisms
- Does NOT sterilise prions — TSE/BSE-associated prion proteins are resistant to gamma radiation
- Film properties after irradiation: slight yellowing (normal), minor reduction in tensile strength — validated per material specification
- Supplied with irradiation certificate: dose mapping, dosimetry report, SAL calculation, certificate of conformance
- All SeamlessBio single-use bags are gamma sterilised at 25 kGy minimum — certificate included with every shipment
Further Reading
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