Hydrophilic coatings are a wettable, low-friction biological and mechanical design that have evolved over the last four decades. Currently, hydrophilic coatings can be the difference between a purposeful and nonfunctional device, especially in the medical field. With the use of hydrophilic coatings, consistent medical device surface properties and technologies can be achieved.
History of Hydrophilic Coatings in the Medical Applications
In 1956, DuPont was the first to patent hydrophilic coating technology with a two-layer system, including bonding and binding coats. Over the years, hydrophilic coatings have included:
- Polyvinylpyrolidone (PVP)
- Polyacrylic acid (PAA)
- Polyethylene oxide (PEO)
- Polysaccharide materials
Prior to the use of these commonly used hydrophilic coatings, the medical community often used coatings such as glycerin, silicone oils and even olive oil to lubricate devices and other instruments. These coatings, along with attempts to use fluoropolymers such as PTFE, were met with limited success as they often made the lubrication difficult to control and often separated from the equipment after insertion. Other issues that these early hydrophilic coatings suffered from included:
- High costs, including expensive plasma processing equipment
- Application difficulties
- Easily scratched or worn from device
Over time, application methods and the bonding process between devices and hydrophilic coatings were improved. In addition, the speed of manufacturing also increased which helped to drive down the costs of hydrophilic coatings and make them more accessible. Today, there is a wide availability of both natural and synthetic hydrophilic coatings, where the choice is determined by the functional requirements of the device.
Medical Industry Applications of Hydrophilic Coated Devices
The fields of cardiology and urology have greatly benefited from hydrophilic coatings that are biocompatible and durable. Since hydrophilic coatings are water-loving they have a low coefficient of friction. As a result, hydrophilic coated medical devices are more easy to use.
The use of hydrophilic coatings in the medical field continues to increase with new coated devices and tools. Peripheral vascular, urologic, cardiologic and ophthalmic fields use hydrophilic coated devices for safe patient care and use. And, with their disposable capacity, hydrophilic coating devices are also used in emergency departments and labor & delivery units of healthcare organizations. Other common hydrophilic coated devices are used for endoscopy and respiratory care.
Guidewires, catheters, and many other invasive medical devices use hydrophilic coatings for feasibility and safety of patient care. Medical devices and instrumentation that is commonly coated with hydrophilic coatings to minimize patient inflammation and enhance comfort include:
- Central venous catheters (CVCs)
- Peripherally inserted central catheters (PICCs)
- Intraocular lens delivery cartridge
- Antimicrobial agents
Hydrophilic Coating Benefits versus Other Medical Coatings
Hydrophilic coatings are biomedically safe over non-hydrophilic coated lubricants and include antimicrobial properties that other coatings do not. Furthermore, hydrophilic coatings have a multipurpose capacity and deliver cost-effective benefits including enhanced functionality and infection fighting functions.