Ensuring a bio-inert surface is essential for numerous industries beyond medical diagnostics. Lets explore what bio-inert coatings are, key factors to consider when selecting one, and why Dursan® is an excellent choice for corrosion resistance and bio-inert applications.
A bio-inert coating is a specialized surface treatment designed to prevent interactions with biological materials. This ensures that the coating does not react, promote chemical activity, or interfere with the biological substances it comes into contact with.
The University of California Division of Agriculture and Natural Resources classifies biological materials as:
Recombinant or synthetic DNA/RNA (e.g., plasmids, cloned materials, siRNA)
Viral vectors (e.g., lentivirus, adenovirus, AAV)
Genetically modified organisms (e.g., microorganisms, plants, animals, cell lines)
Human products (e.g., blood, tissues, bodily fluids, clinical specimens)
Pathogenic microorganisms (e.g., human, animal, or plant pathogens)
Select Agents or Select Toxins
1. Corrosion Resistance
Bio-inert sampling flow paths must withstand aggressive cleaning cycles. We tested Dursan against common stainless steel coatings by immersing them in 15% bleach for 24 hours. The results demonstrated that Dursan outperformed other coatings in corrosion resistance, proving its durability and reliability.
Comparative ASTM bleach immersion studies show Dursan prevents surface attack by preventing interaction of corrosive analytes or cleaning agents with the surface and outperforming other coatings or stainless steel surfaces by an order of magnitude.
2. Food Contact Safety & Biocompatibility
The United States Food and Drug administration (FDA) does not formally "approve" coatings or other materials for food or bio/pharmaceutical contact. Rather, the FDA regulates coatings via the Code of Federal Regulations (CFR), specifically 21 CFR 175.300 which lists what raw materials are acceptable and unacceptable for the formulation of coatings. It is then up to the coating supplier to self-regulate to ensure that they are using raw materials that are acceptable.
According to the FDA, a coating must:
1) Pass the solvent extraction tests listed in 21 CFR 175.300.
2) Contain no heavy metals.
3) All coating components must conform to the materials listed by the FDA in order to be compliant.
These stipulations are also required for NSF/ANSI 51 certification. Dursan successfully meets these requirements and is therefore FDA compliant. Read Our NSF Certification
With respect to pharmaceutical applications, our data suggest that Dursan does not "alter the safety, identity, strength, quality, or purity of the drug product beyond the official or other established requirements" per 21 CFR 211.65.
Nevertheless, we strongly encourage customers to test the use of Dursan in their specific application to verify that performance requirements are met and the customer's production processes and outputs can continue to meet FDA approval guidelines.
3. Metal Ion Barrier and Inertness to Bio Molecules
When testing recovery for oligonucleotides it was found that more metal ion leaching resulted in less oligonucleotides reaching their destination. The coated vs. uncoated mass spec and UV mobile phases differ significantly. For more information on how SilcoTek's coatings help in this application, our Dr. Jesse Bischof goes into much more detail in this awesome video explaining the process.
4. Anti-Stick to Biological Compounds
Protein adsorption, or sticking, occurs when proteins in biological fluids adhere to the surfaces of medical devices. This can cause device malfunction in sensors and diagnostic tools, biofouling that leads to protein films that develop into infections, and the body recognizes proteins as foreign and triggers an immune response.
In 2021, we did a case study with Abbott Labs on reducing protein adhesion on medical diagnostic equipment with Dursan® coating. To look for increased protein resistance, the Abbott group performed tests on a Quartz Crystal Microbalance with Dissipation monitoring or QCM-D, which is a highly sensitive mass sensor that can detect mass uptake or release by interpreting changes in the quartz resonance frequency. The sensors were coated in a thin layer of 316L grade stainless steel and then coated via chemical vapor deposition with SilcoTek’s Dursan process. After treating the QCM-D sensors with a protein solution and gauging the protein adhesion, the following was established. As seen in Image 1 below, a combination of Dursan coating and a wash step containing a non-ionic surfactant facilitated 100% removal of tested proteins. Shown in Image 2, comparison studies between Dursan and AF 1600 (a competitive fluoropolymer coating) showed that sonication degraded the protein resistance properties of the AF 1600 due to delamination, but had no negative impact on Dursan demonstrating the coating’s superior adhesion and more robust performance. This study illustrates what an inert coating can do for stainless steel equipment in any protein adhesion environment, creating fewer false positive tests due to protein carryover and contamination.
Image 1:The combination of Dursan coating and nonionic surfactant in the wash solution led to effective reduction of protein loss to the sensor surface.
Image 2: Wear resistance test using sonication showed robustness of the CVD Dursan coating. In contrast AF1600 coating lost efficiency due to coating delamination.
Dursan is an advanced CVD coating technology that meets all key criteria for bio-inert applications. It is NSF-approved and FDA-compliant, making it a top choice for industries requiring reliable, corrosion-resistant coatings.
Extends the life of medical and analytical instruments
Prevents protein carryover and binding
Improves test consistency and accuracy
Provides superior corrosion resistance
Selecting the right bio-inert coating is crucial for ensuring reliable performance in medical, industrial, and analytical applications. Dursan's superior bio-inert properties, corrosion resistance, and compliance with regulatory standards make it an ideal choice for professionals seeking high-performance coatings.
Interested in learning more? Contact our experts today to find the best coating solution for your needs.