Hospital-acquired infections (HAIs) are also known as healthcare-associated infections. These infections continue to pose a major challenge to healthcare systems worldwide. According to the World Health Organization (WHO), millions of patients develop infections during hospitalization each year. This leads to increased morbidity, mortality, prolonged hospital stays, and higher healthcare costs. Preventing microbial colonization of medical device surfaces has become an essential objective in the design of these devices. 1 It requires new capabilities and innovation in designing sophisticated medical devices, such as catheters, guidewires, endoscopes, implants and surgical instruments. Non-Leaching Antimicrobial Coatings are a promising technology in this area.
Traditional, silver-based, or other active agent-based antimicrobial coatings have been used, but they have several limitations. These limitations have led the medical device industry to explore new options for fighting HAIs. This exploration has resulted in the development of advanced, non-eluting antimicrobial coatings technologies. These provide long-lasting protection, but do not leach (or release) biocides into the environment. 3,4These new, non-leaching technologies are the focus of this article.
This article examines the increasing trend towards non-leaching, “contact-killing” coating technologies to provide antimicrobial characteristics to surfaces. Furthermore, we use Hydromer®, Inc.’s 40+ years of coatings expertise to explore the advantages of these innovative, antimicrobial surfaces that kill microbes without the release of any active chemicals. At the end we discuss how these antimicrobial coatings can be effectively applied to surfaces using automated coating application methods.
Related: Antimicrobial Coatings: What they Are & How they Work
Traditional Antimicrobial Coating Technologies
For years, the primary means of reducing bacteria contamination and HAIs has been using silver-based antimicrobial coatings. These technologies have proven to be effective in many applications.2
Traditional antimicrobial coatings have relied on the controlled release of active agents such as:
- Silver ions
- Copper ions
- Chlorhexidine
- Antibiotics
- Quaternary ammonium compounds
- Antimicrobial peptides
These technologies function by continuously releasing antimicrobial substances into the surrounding environment.3,4
These have been effective in many regards. However, there are concerns regarding their poor durability, depletion of active agents over time, possible toxicity, and the development of antimicrobial resistance.
We talk about the limitations of these traditional antimicrobial coating technologies below in more detail.
Limitations of Traditional Antimicrobial Coatings
While effective initially, traditional antimicrobial coatings present several limitations:
- The antimicrobial agent is gradually depleted over time. Once the active ingredient is exhausted, the coating loses effectiveness.
- Continuous exposure to sub-lethal concentrations of antimicrobial agents may contribute to adaptive microbial responses and antimicrobial resistance concerns.
- Eluting antimicrobial technologies are often subject to more complex regulatory evaluations because the released substances may be considered active pharmaceutical ingredients.
- Released antimicrobial compounds may accumulate in wastewater streams and healthcare environments.
- Some eluting systems can affect device performance, coating integrity, or biocompatibility over extended periods.
These limitations have fueled interest in creating permanent, antimicrobial surfaces that maintain efficacy without releasing active chemicals.
Non-eluting, antimicrobial coatings, developed by coating leaders such as Hydromer, Inc. are one of the most exciting innovations in medical device surface engineering today. These innovative coatings kill bacteria that they come into contact with, while they are permanently bonded to the surfaces of the medical devices. They provide long-lasting protection for the entire lifecycle of the medical devices.5,6
Non-Leaching Antimicrobial Coatings
Non-leaching antimicrobial coatings are also known as non-eluting antimicrobial coating. These coatings are permanently adhered to the substrate material and effectively kill or inhibit microorganisms on contact.
Traditional antimicrobial coatings release their active ingredients into the surrounding environment. In contrast, non-leaching antimicrobial coatings depend on antimicrobial actions that are bound to the surface of the coating. Non-leaching coatings have an actual antimicrobial component chemically bonded to the coating matrix. Therefore, the surface will be antimicrobial for the life of the product.5,6
What happens when bacteria, fungi, or other living microorganisms come into contact with the non-leaching coated surface?
They are killed at the interface (or on the surface of the coating) without the need for any antimicrobial agent to be released. These coatings create a long-lasting and effective antimicrobial barrier, which will last well beyond the effective lifespan of traditional release-based coatings.
Non-Leaching Technologies for Contact-Killing Antimicrobial Surfaces
Several technologies are employed to prepare non-eluting antimicrobial coatings.6-8 Some of the most notable ones are briefly discussed below.
- Immobilized Quaternary Ammonium Technologies: Surface-bound quaternary ammonium compounds (QACs) can disrupt microbial cell membranes upon contact. Because the antimicrobial molecules are covalently attached to the coating, they remain fixed on the surface while maintaining bactericidal activity.9
- Cationic Polymer Coatings: Certain positively charged polymers interact with negatively charged bacterial membranes, causing membrane disruption and cell death.10
- Antimicrobial Organosilanes: Organosilane-based antimicrobial surfaces form covalent bonds with substrates while presenting antimicrobial functional groups at the coating surface.11
- Surface-Engineered Nanostructures: Some coatings utilize nanoscale topographies inspired by natural antimicrobial surfaces such as insect wings. These structures physically damage bacterial membranes upon contact.12
- Immobilized Antimicrobial Peptides: Advances in surface chemistry now allow antimicrobial peptides to be permanently tethered to coating surfaces while retaining biological activity.13
Benefits of Non-Eluting Antimicrobial Coatings
These coatings offer many benefits over traditional technologies.
1. Long-Term Antimicrobial Protection
The active functionality remains permanently attached to the coating. As a result, antimicrobial performance can persist significantly longer than conventional release-based systems that become exhausted over time.
2. Reduced Risk of Antimicrobial Resistance
Microorganisms are killed through direct surface contact rather than prolonged exposure to released agents. In turn, opportunities for developing resistance may be reduced.
3. Improved Patient Safety
The absence of continuous chemical release minimizes concerns regarding systemic exposure and local toxicity.
4. Environmental Sustainability
Non-leaching systems reduce the release of antimicrobial compounds into healthcare facilities and wastewater streams.
5. Regulatory Advantages
Active agents remain immobilized. As a result, some non-leaching technologies may present a simpler regulatory pathway compared with drug-eluting antimicrobial systems.
6. Consistent Surface Performance
The coating continues functioning without depletion. This helps maintain consistent antimicrobial protection throughout the product’s intended use period.
7. Compatibility with Other Functional Coatings
Non-leaching antimicrobial technologies can often be integrated with a wide range of other coatings, including:
- Hydrophilic coatings
- Lubricious coatings
- Anti-thrombogenic coatings
- Anti-fouling coatings
- Wear-resistant coatings
This enables multifunctional surface engineering for advanced medical devices.
Applications in Medical Devices
Non-eluting antimicrobial coatings are increasingly being evaluated and deployed across numerous healthcare applications.14-18 Example applications include the following:
Catheters
Urinary catheters, central venous catheters, and vascular access devices are highly susceptible to bacterial colonization and biofilm formation. Contact-killing coatings for surfaces can help reduce infection risk while maintaining device functionality.
Guidewires and Interventional Devices
Combining antimicrobial and lubricious coating technologies may improve both infection control and device maneuverability.
Orthopedic Implants
Permanent antimicrobial surfaces can help reduce bacterial attachment to implant materials while preserving osseointegration properties.
Surgical Instruments
Durable antimicrobial coatings may provide an additional layer of protection between sterilization cycles.
Wound Care Devices
Advanced antimicrobial coatings can help suppress microbial contamination while supporting wound healing environments.
Hospital Equipment
Touch surfaces, medical carts, monitoring equipment, and high-contact components can benefit from persistent antimicrobial protection.
Compatibility with Automated Coating Systems
Modern, non-leaching antimicrobial technologies are compatible with high-volume automated coating methods. This represents one of the most significant benefits provided by these technologies.
There is an increasing demand for scalable manufacturing methods from medical device manufacturers. In turn, the ability to utilize automated coating systems provides the necessary consistency, throughput, and quality assurance needed for a commercial product.19-22
Coating Application Methods for Non-Leaching, Antimicrobial Coatings
These coating can be applied to substrates using multiple application methods. Some of the most common methods are discussed below.
1. Automated Dip Coating
Dip coating remains one of the most widely used methods for applying antimicrobial coatings to:
- Catheters
- Guidewires
- Tubing
- Implantable components
During automated dip coating, devices are immersed in a coating solution and withdrawn at controlled speeds to achieve uniform coating thickness.
Benefits include:
- High reproducibility
- Excellent coating uniformity
- Scalable production
- Reduced operator variability
2. Spray Coating Systems
Robotic spray systems can apply antimicrobial coatings to complex geometries and large surface areas.
Advantages of this method include:
- Precise coating control
- Reduced material waste
- High production efficiency
- Suitable for intricate device designs
3. UV-Curable Coating Platforms
Many modern antimicrobial coating formulations are compatible with UV-curing technologies.
Benefits of UV-Cure Coating Systems include:
- Rapid curing times
- Increased production speed
- Lower energy consumption
- Reduced manufacturing footprint
- Improved process control
UV-curable, antimicrobial systems can be integrated into automated production lines, enabling continuous, high-throughput manufacturing.
A coating system designed for large-scale production that focuses on catheter-based products has been developed through a partnership with JMedtech and Hydromer, Inc. The system is completely automated, has multiple modules (e.g., loading units, dip-coating modules, UV curing), and requires minimal human interaction. The only human operator is typically one individual, who manages the system.
The automated system is able to produce a high number of products in a short amount of time. It is also capable of providing consistent quality and accurate coating application through controlled dip, rotation, and UV curing parameters.
Therefore, the automated coating system is a complete solution for the application of hydrophilic and functional coatings on medical devices. The system will provide customers with improved consistency, lower labor cost, and support the production of medical products at an industrial scale.23
Hydromer® Non-Leaching Antimicrobial Coating Technologies
Hydromer® non-leaching antimicrobial coatings are custom formulas based on our hydrophilic coating technologies. They help prevent the possibility of infections on medical device surfaces. They utilize durable, non-leaching antimicrobial technologies. This means they remain bonded to the device surface without the need to continuously release active antimicrobial agents.
Another benefit of our coatings is that they can be utilized in combination with Hydromer®’s lubricious and hydrophilic coating systems. This allows for the creation of multifunctional, lubricious surfaces that also prevent microbial contamination.
These systems can be applied using automated coating equipment and UV curing processes. This ensures consistency in coating quality as well as scalability and efficiency in manufacturing. They can easily be integrated into high volume production lines for the manufacture of medical devices.
Hydromer® solutions actively address a growing industry focus on reducing HAIs and providing improved patient outcomes.8,23
Conclusion
More and more hospitals are changing their antimicrobial technologies for abiotic surfaces. The goal is to help prevent hospital-acquired infections (HAIs). Silver- and drug-eluting coatings are useful for infection control. However the industry is increasingly moving away from these types of coatings and toward non-leaching antimicrobial coatings. These technology provides long-term, durable protection without releasing active agents into the surrounding environment.
Non-leaching (i.e., contact-killing) surfaces provide safety, sustainability, compliance with regulatory standards, and more. And they do this while providing consistent antimicrobial performance throughout the use of a medical device.
They can also be applied with automated coating processes (ex: dip coating, robotic spray coating, precision dispensing, and UV curing). All of these factors make them a feasible, commercially attractive, and scalable solution for the manufacture of next-generation medical devices and healthcare equipment.
References
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