ISO 10993 Testing for PVDF Filament and Cable Ties
What cytotoxicity testing tells us about a material
Chemical resistance, temperature capability and strength are familiar considerations when selecting PVDF. In pharmaceutical, bioprocessing and laboratory environments, another question can matter: how do substances released from a material affect living cells?
ISO 10993-5 cytotoxicity testing provides evidence to help answer that question. Independent testing of Fluorinar-C™ PVDF filament and two Strong-Ty® cable tie models produced Grade 0 results, meaning no reactivity, at both 24 and 48 hours.
What ISO 10993 Measures
ISO 10993 is a family of standards used in the biological evaluation of medical devices. Part 5 addresses in vitro cytotoxicity: the effect of a material or its extracts on cultured cells. “In vitro” means outside a living body under laboratory conditions. “Cytotoxicity” means toxicity to cells.
Cytotoxicity is one part of biological evaluation. A result under ISO 10993-5 answers a specific question about cell response; it does not establish that every biological requirement has been addressed.
How the Testing Works
The Nile Polymers studies used a Minimum Essential Medium extract, commonly called an MEM extract test. The laboratory immersed prepared samples in a liquid under controlled conditions, then exposed living cell cultures to that liquid and examined their response.
All three samples were autoclaved at 121 °C for 30 minutes before testing. Extraction took place at approximately 37 °C for 24 hours. The resulting extracts were applied to L-929 cell cultures and evaluated at 24 and 48 hours for changes in appearance, growth and cell integrity.
Positive and negative controls confirmed that the test system could distinguish a cytotoxic response from a nonreactive response. The controls behaved as expected in each study.
Understanding Grade 0
The method used a scale from Grade 0, no reactivity, to Grade 4, severe reactivity. A grade greater than 2 was considered a cytotoxic effect. Each Nile Polymers sample achieved Grade 0 in all three replicate cell-culture wells at both observation times.
This means the extracts produced no observed reactivity under the test conditions. It does not mean that the material contains no extractable substances. Identifying those substances and measuring their concentrations requires a different type of analysis.
The Nile Polymers Results
| Tested product | Result at 24 and 48 hours |
|---|---|
| Fluorinar-C™ PVDF filament | Grade 0 — no reactivity |
| Strong-Ty® 4-inch standard tie NPC204N |
Grade 0 — no reactivity |
| Strong-Ty® 8-inch tie NPC208N |
Grade 0 — no reactivity |
These findings apply to the identified products and test conditions. They should not automatically be extended to other filament formulations, colors or cable tie models, including the 4-inch Flex and Blue ties.
Why Testing Matters for 3D Printing Filament
Cytotoxicity testing adds a documented biological response to a filament’s physical and chemical property data. For engineers reviewing materials for laboratory tooling or equipment used around a bioprocess, that information can support selection and qualification decisions.
The Fluorinar-C™ report evaluates filament. Printing introduces another manufacturing step. Nozzle condition, previously processed materials, bed adhesives, supports and cleaning procedures are examples of factors to consider when evaluating a finished part. The relevance of these factors depends on the intended application and contact conditions.
A tested filament provides a documented starting point. Users must determine whether the finished part meets their application requirements. Fluorinar-C™ is not intended for implantation in the human body.
Why Testing Matters for Cable Ties
For the standard 4-inch and 8-inch Strong-Ty® models, testing was performed on molded cable tie samples. The results provide product-specific evidence for customers reviewing components used around pharmaceutical and bioprocessing equipment.
A tie securing the outside of tubing on a bioprocessing bag assembly has a primarily mechanical function. When the tie remains outside the fluid path, the cytotoxicity report can support material documentation. Its significance depends on the actual exposure pathways and the customer’s requirements; it does not qualify the entire assembly.
Mechanical performance remains a separate consideration. Cytotoxicity testing does not measure tensile strength, locking performance or creep. If ties are sterilized before tightening, their installation and strength after the intended process should be evaluated separately.
Putting the Results to Work
The Grade 0 results were obtained after the documented autoclave preparation. They do not establish performance after repeated sterilization cycles or other sterilization methods. Cytotoxicity testing also does not establish sterility, endotoxin levels or particle shedding.
The studies were conducted for non-regulatory purposes and were not intended to meet FDA cGMP or GLP requirements. Customers planning a regulatory submission should assess the reports’ suitability for that purpose.
For material selection, the value is clear: identified Fluorinar-C™ filament and Strong-Ty® cable tie samples showed no cytotoxic reactivity under the study conditions. Contact info@nilepolymers.com with the product name or part number to request supporting documentation.
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