Sterilization destroys all forms of microbial life on medical device surfaces. It is a vital process used before or after medical procedures in nearly every healthcare facility. The majority of medical devices have medical coatings on their surface. In turn, any coating on a device that undergoes sterilization needs to be able to withstand these procedures.
Various agents and processes are used to sterilize medical device surfaces. These include steam under pressure, dry heat, ethylene oxide (EtO) gas, hydrogen peroxide gas plasma, and liquid chemicals. The appropriate sterilization method depends on the type of surface and the coatings.
Medical coatings are critical for enhancing the safety and performance of medical devices. At the same time, sterilization is a critical process to prevent microbial growth and ensure long-term patient safety. In turn, successful medical coatings must be able to withstand repeated sterilization without breaking down. Customizable UV-cured hydrophilic coatings are a common type of surface treatment used on medical devices. These offer greater durability during repeated sterilization than thermal-cured coatings and other types of coatings.
In this article we review UV-cured hydrophilic coatings’s ability to withstand various, required sterilization processes. We begin with the importance of sterilization in modern healthcare. Then we take a deep dive into UV-curable medical coatings and their ability to withstand repeated sterilization.
The Role of Medical Device Sterilization for Reliability and Performance
Sterilization frees medical device surfaces from microbiologic life. The main purpose of this critical process is to prevent disease transmission associated with the use of contaminated medical devices. Sterilization of medtech devices and equipment is important not only in microbiology but across numerous other related fields as well.
Below are the most common benefits of sterilization:
- Ensures the ability to reuse devices safely
- Allows the safe use of invasive and minimally invasive medical equipment
- Lowers the number of unsterilized bacteria
- Eliminates the microbial growth environment ideal for reproduction
- Prevents corrosion
In the process of sterilization, medical devices are exposed to various sterile agents, such as ethylene oxide gas or wet heat. It is mainly beneficial (and critical) in the case of medical devices that come in contact with sterile body tissues or fluids.
Comparing Sterilization vs Disinfection
Sterilization kills germs and neutralizes harmful organisms that can cause diseases. It is useful on medical device surfaces as well as in liquids.
On the other hand, disinfectants eliminate most pathogens, but fail to kill all types of microbes. Examples of disinfectants are iodine, phenol, and chlorine. Disinfection is useful in case of semi-critical or noncritical medical items.
Most Common Sterilization Techniques for Medical Devices
The healthcare industry relies on the combination of medical device sterilization methods discussed below to completely remove microbes that can cause infections. Microbial life on medical devices can lead to serious issues after medical procedures.
- Autoclaving (Steam or Wet Heat Sterilization): This is one of the most popular sterilization methods. It utilizes pressurized steam to kill microbes through hydrolysis and coagulation of cellular proteins. Autoclaving is nearly 100% effective. It kills the spores and viruses present on the surface of medical devices. The device is placed in a sealed chamber and exposed to a high-pressure steam of about 15 psi or higher.
- Dry Heat Sterilization: Similar to autoclaving, this one also comes under thermal sterilization. The only difference is that instead of wet steam, it utilizes hot air to sterilize the medical device surfaces. The hot air can reach up to 180°C. Such hot air is circulated through an insulated chamber to maintain the temperature and kill the maximum amount of microbes.
- Radiation: Electromagnetic radiations, such as UV light, gamma rays, or X-rays are used to completely destroy the DNA of microbes. Such method is particularly useful in the case of medical devices with complex geometries. It penetrates deep into materials and kills germs and microorganisms. Radiation is one of the most used methods to sterilize already-packaged products. The medical devices are placed inside a sterilization chamber and exposed to a controlled dose of radiation over a calculated period.
- Filtration: In this method, liquids or gases are passed through a filter to remove organisms. Filtration is the fastest way to remove microbes without any heat or chemical solvents. Such filters have pore sizes so small that microbes more than 2.2 micrometers fail to pass through them. In some cases, the pore size is designed to be ≤0.1 µm for maximum separation. All types of antibiotics, enzymes, and medical solutions are passed through such filters. It does not kill microbes, so it cannot be used for terminal sterilization.
- Chemical Sterilization: This process is one of the most common and cost-effective methods to remove microbial life from the surface of medical devices. It uses chemical solvents such as ethanol and isopropanol to kill germs and microorganisms. This sterilization method is less effective in eliminating spores compared to thermal-based sterilization processes.
- Gas Sterilization: Ethylene oxide (EtO) gas is used to kill microbes present on heat- and moisture-sensitive medical equipment. Such gas alkylates microbial DNA and prevents cell metabolism or replication. The gas is toxic and can cause serious issues when left untreated post-sterilization.
Thermal processes are the most commonly used sterilization methods. By controlling heating duration and temperature range, the operators can adjust the level of sterilization. However, these methods cannot be used across all scenarios as the heat may damage the medical devices or their surfaces.
Why Medical Coatings Need to be able to Withstand Sterilization
The ability to successfully sterilize a medical device is largely affected by its materials. It is the reason why the experts suggest using heat-stable materials to design an invasive medical device. This suggestion applies to both the materials used in the construction of the medical device as well as the coatings applied on the surfaces.
Medical-grade coatings have completely revolutionized the healthcare industry. Nowadays, they are applied to almost all invasive or interventional medical devices. But it is important to note that such coatings may suffer damage due to high-heat, chemicals, or even radiation used during sterilization.
The damaged coating may cause issues, such as blood clotting, increased friction between the medical device surface and surrounding tissues, and reduced overall efficiency of medical devices.
To prevent these complications, coatings must be formulated to withstand sterilization without becoming damaged or causing issues.
6 Heat-Stable Medical Coatings that Can Withstand Sterilization
There are various types of medical coatings used in the medical device industry. However, not all of them can withstand intense environments or terminal sterilization. It is also important to note that different variations of the different coatings may perform differently. Coating formulation and curing methods, for instance, may impact how well a coating can withstand sterilization.
1. Hydrophilic Coatings
These polymer-based medical coatings offer excellent sterilization compatibility. If formulated correctly, they are able to maintain their integrity after exposure to various sterilization processes.
Their main purpose is to reduce friction between the medical device surface and biological tissues, enhancing device maneuverability and minimizing patient trauma. However, advanced hydrophilic coatings can be customized to provide many benefits. These include improved antimicrobial protection and compatibility with a range of sterilization methods.
Manufacturers such as Hydromer®, Inc. offer both UV and thermal curable hydrophilic coatings. For devices needing repeated sterilization, UV-curable hydrophilic coatings are preferred. Reasons for choosing UV-curable coatings over thermal-cured types are discussed in the next section (stay tuned).
Hydrophilic coatings are gaining huge popularity due to their customization ability. For example, apart from excellent lubricity, these coatings are known to provide best-in-class antimicrobial properties, thromboresistance, drug-eluting capabilities, and more.
sTo learn more about hydrophilic coatings and their critical advancements in the field of healthcare, click here: Hydrophilic Coatings for Medical Devices: Intro, Benefits & Uses.
2. Parylene Coatings
Parylene coatings create an ultra-thin, pinhole-free layer that uniformly covers the medical device surface. This protective barrier ensures chemical resistance, prevents moisture ingress, and maintains device accuracy. As a result, these coatings are compatible with most sterilization methods due to their inert nature and high dielectric strength. These properties help sustain device performance and reduce contamination risk during repeated sterilization cycles.
They can easily withstand extended exposure to EtO (ethylene oxide) gas, radiation, and wet steam of selected grades.
These coatings are mostly applied to wearables, sensors, and other implantable medical devices.
3. PTFE Coatings
Polytetrafluoroethylene (PTFE) coatings are widely used for medical tubes, guidewires, and catheters because of their extremely stable chemical structure. These coatings resist reactions with bodily fluids and sterilants, provide lubricity, minimize tissue adhesion, and reduce the chance of inflammation. Their non-reactivity ensures that device functionality is maintained even after repeated sterilization.
Due to their chemical and thermal stability, PTFE coatings can withstand a wide range of sterilization methods.
Learn more about PTFE Coatings and Their Alternatives.
4. Silicone Coatings
Silicone coatings can withstand autoclaving and radiation-based repeated sterilization without degrading. This makes them suitable for devices requiring frequent reprocessing. Their robust Si–O bonds provide both thermal and chemical stability. This ensures continued device flexibility, biocompatibility, and consistent performance after multiple sterilization cycles.
Learn more about Silicone Coatings and their Alternatives.
5. Ceramic Coatings
These coatings are applied to medical devices and implants that require excellent wear resistance and biocompatibility. Examples include heart replacement valves and dental implants.
Ceramic coatings made up of titanium dioxide (TiO₂) and zirconia (ZrO₂) provide exceptional resistance to sterilization.This is due to their rigid inorganic polymer backbone. These coatings maintain surface hardness, highly wear-resistant properties, and biocompatibility. Their durability ensures that medical devices such as heart valves and dental implants keep essential performance characteristics, like low wear and inflammation risk, even after numerous sterilization cycles.
6. Metal Coatings
Metal coatings include stainless steel on medical instruments like forceps and scissors. These are capable of withstanding all types of sterilization processes without corrosion or loss of strength. This ensures the devices remain reusable and safe over time.
Metal-based coatings are strong and used in medical applications due to their mechanical durability and corrosion resistance within the biological environments. They are inherently strong and compatible with all popular sterilization methods discussed above.
However, metal coatings do not offer the lubricity and other benefits of other options, such as hydrophilic coatings.
The Sterilization Performance Comparison of UV-Cured and Thermally Cured Hydrophilic Coatings
UV-curable hydrophilic coatings, such as Hydromer’s HydrUV generally outperform thermally cured coatings for applications requiring a balance of enhanced durability, faster processing times, and long-term lubricity.
Superior sterilization compatibility is one benefit where UV-cured hydrophilic coatings dominate thermally-cured coatings. These UV coating variations can withstand gas, chemical, and radiation-based sterilization more effectively without any loss of properties. This is due to their crosslinking density and controlled polymer network after curing.
On the other hand, thermally cured hydrophilic coatings rely heavily on linear or lightly crosslinked polymer networks. As such, they are not as compatible with a wide range of sterilization techniques. Additionally, their performance reduces when using a few techniques, including radiation-based sterilization.
Finally, note that UV- and thermally-cured hydrophilic coatings are not suitable for high-heat sterilization or autoclaving.
HydrUV™ UV Curable Hydrophilic Catheter Coatings by Hydromer®
Hydromer®, Inc. is a custom medical device coatings manufacturer based in the United States. We have 40+ years of experience manufacturing and supplying clinically proven and trusted hydrophilic coatings. HydrUV™ is our newest addition to our medical coatings line. It is a UV-curable hydrophilic coating with best-in-class lubricity and sterilization compatibility.
We use only the highest quality ingredients to manufacture our UV-curable medical coatings. Our goal is to overcome conventional challenges associated with UV-cured medical coatings. For instance, these coatings seamlessly integrate into automated production lines without compromising coating uniformity, even on complex geometries. We can customize both our UV-curable HydrUV™ and our conventional thermally-cured hydrophilic coatings to exhibit enhanced sterilization resistance.
Our HydrUV™ coatings can be applied to a variety of medical devices. We do not just offer off-the-shelf products. Rather, HydrUV™ can be custom formulated to your needs. It ensures we can formulate a solution to meet your specific product requirements.
Request Samples, Test HydrUV™ UV Coatings Yourself
Interested in testing our UV-curable, sterilization-compatible, hydrophilic medical coatings for your medical device?
Please feel free to contact our coatings team for more information or to order samples.
Hydromer®, Inc. is more than just a coatings supplier. We help our clients focus on their core strengths while helping them bring advanced products to market quickly. From coating formulation to our line of extensive coating services, our team can help you no matter what stage of the product development process you are in.
