The medical device industry is constantly changing to meet the increasing need for precision, cleanliness, and dependability. It is also always innovating to improve patient outcomes and reduce healthcare costs. One important advancement in coating medical products is ultraviolet (UV) curing technology. UV curing is a process that uses strong ultraviolet light to quickly turn liquid materials into solid forms. UV coatings are not the most suitable for every medical device application, but they are helpful in several.
This article will explain how UV curing works and how it is used for manufacturing certain medical devices. We also discuss specific chemistries used, such as PEG, PVP, and chitosan. Lastly, we provide examples of medical devices and products that use UV curing technology.
What is UV Curing?
UV curing is a process that uses ultraviolet (UV) light to start a chemical reaction called photopolymerization. This reaction changes liquid, such as liquid coatings, into solid forms quickly.
In this process, substances known as photoinitiators absorb the UV light. When they do this, they produce tiny particles called free radicals or cations. These particles are what kick off the polymerization process. And this process leads to the formation of solid materials. In the case of coatings, this would be the hardened, coated surface.
The quick nature of photopolymerization makes UV curing useful for creating things like coatings, adhesives, and protective layers that have great qualities.
Pros and Cons of UV Curing in Medical Applications
UV coatings are not the best fit for every medical device application. This is why it is beneficial to work with a company like Hydromer, Inc. who offers a wide range of medical coatings and curing methods, including both thermal and UV cured coatings.
Below we give some of the key pros and cons of UV coatings for medical applications.
PROS
- Speed: Allows coatings to cure quickly.
- Precision: High control over coating thickness and uniformity.
- Clean Technology: Solvent-free systems reduce toxic emissions.
- Durability: Improved mechanical strength, chemical resistance, and biocompatibility in some applications.
CONS
- Not suitable for complex shapes and structures. In these cases thermal cure coatings are a better option.
- Adherence issues with specific substrates. In these cases, other coating types, such as thermal cure coatings can be a better option.
- Higher initial cost for set-up
- Ineffectiveness with thicker coatings due to limited penetration (cure depth) – this is an issue where thicker coatings are needed. In these cases thermal cure coatings are a better option.
If you need help understanding which type of coating is best for your product or company, we can help. Contact us to talk to one of our coating experts.
UV Coatings for Medical Device Manufacturing 1,2
Medical devices require sterility, biocompatibility, and structural integrity. In many cases, UV curing technology fulfills these requirements. Some applications that UV coatings can be designed for include:
Key Applications for UV Cure Coatings 1,3,4
- Catheters and Tubing: UV-cured coatings enhance flexibility, lubricity, and durability. Learn more about hydrophilic catheter coatings.
- Syringes and Needles: UV adhesives enable strong bonding without heat damage.
- Surgical Instruments: Protective coatings improve corrosion resistance and cleaning ease.
- Dental Devices: UV-curable resins are used for fillings and restorations.
- Implantable Devices: UV-cured materials ensure long-term stability and biocompatibility.
The Role of PEG, PVP, and Chitosan in UV Curing
The choice of polymers significantly impacts the performance and biocompatibility of a UV-cured coating. PEG, PVP, and chitosan are among the most commonly used polymers in medical UV-curing systems.
Below we discuss each of these chemistries and their role within UV medical coatings.
1. Polyethylene Glycol (PEG)
PEG and Its Role in UV-Cured Materials
PEG is often added to UV-cured materials because of certain, helpful properties. For example, PEG has a low viscosity and is water-loving (hydrophilic). This makes it suitable for hydrophilic coatings, which are used extensively for medical devices. It works as a plasticizer, which means it makes the final polymer stronger and more flexible. Additionally, when PEG is mixed with chitosan, it has been shown to make chitosan more ductile and improve its strength. PEG can also help increase the strength and flexible properties of UV-cured films that can change with temperature.5
In turn, PEG is important as it can help in making the properties of materials better.
- Properties of PEG: Hydrophilic, biocompatible, and flexible
- Role of PEG: Used in UV-curable formulations as PEGDA or PEGDMA, such as coatings for medical devices.
- Applications: Hydrogels for drug delivery, anti-fouling coatings, soft contact lenses, and wound dressings.
2. Polyvinylpyrrolidone (PVP)
Polyvinylpyrrolidone (PVP) is an important material used in the creation of UV-cured products. This is especially the case in the biomedical field.
PVP has special properties that make it a suitable option for medical devices. These include biocompatibility, low toxicity, and the ability to form strong films.
Another key benefit of PVP is that it is hydrophilic. This property means the surface has high wettability. This creates a “slippery-when-wet” surface. In other words, it helps prevent unwanted substances from sticking to the surface of biomaterial. This is important for devices that need to be in the body for a long time, requiring thromboresistance.
When PVP is used in a UV-curing process, it provides some benefits. For instance, it helps increase the strength and durability of the coatings. This means that the films are not only stronger but also more resistant to damage from chemicals. The UV-curing process also changes the surface properties of the materials. This combines the natural advantages of PVP with even better stability and performance through reactions that happen when exposed to light.6,7
- Properties of PVP: Non-toxic with excellent film-forming capabilities
- Role of PVP in Coatings: Functionalized PVP enhances flexibility, adhesion, and biocompatibility in formulations
- Applications: Drug delivery films, bioadhesives, hydrogels, and medical coatings
3. Chitosan for UV Curing
Chitosan is a natural substance made from chitin. This is found in the shells of crustaceans like shrimp. It is often added to UV-curable products. This is because it is safe for living things and can break down naturally in the environment.
When chitosan is included, it helps make the final product stronger. It can also change how the surface of the cured materials feels or looks.
Research has shown that hydrogels made with chitosan not only have great strength but also have antibacterial properties when cured with UV light.8 This is particularly advantageous in biomedical applications. Chitosan’s inherent properties can improve the functionality of hydrogels used for tissue engineering or drug delivery systems.9-11
- Chitosan Properties: Biodegradable, biocompatible, and antimicrobial.
- Role of Chitosan: Modified to form UV-curable systems that retain biological properties.
- Applications: Wound dressings, tissue engineering scaffolds, dental adhesives, and antimicrobial coatings.
Notable UV-Cured Medical Products
- Hydrogel Wound Dressings: PEGDA and chitosan-based hydrogels promote healing. Learn more about hydrogel dressings.
- Contact Lenses: Hydrophilic lenses made from PEG and PVP derivatives.
- Dental Resins: UV-cured composites for restorative dentistry.
- Surgical Coatings: Antimicrobial, lubricious coatings based on PEG and chitosan.
- Implant Coatings: UV-cured layers enhance tissue integration and prevent infections.
- Drug-Eluting Stents: Controlled drug release with PEG and PVP-based UV-cured matrices.
When UV Curing is Not a Fit
UV coatings are useful in many cases and have their benefits. However, they are not suitable (or the best option) for certain applications.
For instance, UV coatings are not suitable for:
- Complex shapes and structures
- Certain substrates that pose adhesion issues with UV coatings
- Applications requiring thicker coatings – this is due to the limited penetration (cure depth) of UV cured coatings.
Thermal cured coatings are often a great choice for applying a hydrophilic coating to medical devices. They also can be used in the situations above when a UV coating is not suitable.
You can learn when to use each of these coatings in our in-depth guide on UV Coating vs Thermal Coating Review: Which one should you choose?
As we mentioned above, it is beneficial to work with a company like Hydromer. The reason is that we offer a wide range of medical coatings. Our experts can help you select (or we can formulate) the right coating using the optimal curing method, including thermal and UV cured coatings.
Hydromer’s Role in Advanced UV-Curable Coatings for Medical Devices
Hydromer, Inc. is a medical coatings manufacturer based in North Carolina, USA. Our company supplies both advanced thermal cure and UV-curable coatings for use in medical devices. You will not be limited to a standard line of coatings. That is because all of our hydrophilic medical device coatings are fully customizable. This means we can formulate a coating to meet your specific product requirements.
Our advanced medical device coatings successfully adhere to a wide range of substrates. These include nylon, Pebax, polyurethanes, silicone, and metals. Their properties make them suitable for many medical devices, such as catheters, guidewires, stents, implants, and more.
What sets us apart from our competitors is our extensive line of product development and manufacturing services we offer. These services range from technical and regulatory consulting to contract R&D and coating services. In addition, we offer analytical testing services, as well as technology transfer and machine building services. Get the expert help you need, no matter where you are in the product development process.
Conclusion
UV curing technology has become important in making modern medical devices. While it is not suitable for every application, it is useful for several. Using a combination of curing methods, such as UV and thermal curing, allows you to find a suitable coating no matter what the application is. Working with an expert partner like Hydromer can help you pinpoint the right coating for your specific application.
Materials like PEG, PVP, and chitosan improve the usefulness and safety of UV-cured coatings. This has led to new uses, such as wound dressings, dental materials, contact lenses, and drug-releasing stents. With new developments in coating technologies, Hydromer Inc continues to play a significant role in medical innovation and improving patient care.
References
Click to see references.
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6. Charyton M, Deboli F, Fischer P, Henrion G, Etienne M, Donten ML. Composite Anion Exchange Membranes Fabricated by Coating and UV Crosslinking of Low-Cost Precursors Tested in a Redox Flow Battery. Polymers. 2021;13(15). doi:10.3390/polym13152396
7. Louie SM, Gorham JM, Tan J, Hackley VA. Ultraviolet photo-oxidation of polyvinylpyrrolidone (PVP) coatings on gold nanoparticles. Environmental science Nano. 2017;4doi:10.1039/c7en00411g
8. Poon YF, Cao Y, Liu Y, Chan V, Chan-Park MB. Hydrogels Based on Dual Curable Chitosan-graft-Polyethylene Glycol-graft-Methacrylate: Application to Layer-by-Layer Cell Encapsulation. ACS Applied Materials & Interfaces. 2010/07/28 2010;2(7):2012-2025. doi:10.1021/am1002876
9. Renbutsu E, Hirose M, Omura Y, et al. Preparation and biocompatibility of novel UV-curable chitosan derivatives. Biomacromolecules. 2005;6(5):2385-2388.
10. Li B, Wang L, Xu F, et al. Hydrosoluble, UV-crosslinkable and injectable chitosan for patterned cell-laden microgel and rapid transdermal curing hydrogel in vivo. Acta biomaterialia. 2015;22:59-69.
11. Thai NLB, Beaman HT, Perlman M, Obeng EE, Du C, Monroe MBB. Chitosan Poly(vinyl alcohol) Methacrylate Hydrogels for Tissue Engineering Scaffolds. ACS Applied Bio Materials. 2024/12/16 2024;7(12):7818-7827. doi:10.1021/acsabm.3c01209
