3 Questions You Should Ask about Surface Coatings

Biocoat Inc. (Horsham, PA) plays an important role in the medical device industry with its Hydak-brand immobilized hyaluronan coatings technology, which can be applied on most commonly used polymers and metals using a relatively simple process using conventional coating equipment and curing ovens. 

"We are strictly there for those clients that want lubricity, and they want to be able to pull in and out. They want to go into the femoral artery, snatch out an embolism and pull it right out," Biocoat president and CEO Keith Edwards said after a Wednesday talk at MD&M Minneapolis. 

When that is the need, there are generally two types of coatings to turn to: polyvinylpyrrolidone (PVP) and hyaluronic acid (HA).

Edwards has explained to Qmed before that most medical device coatings available today are based on PVP, a well-known biocompatible material with a long, established history as a blood substitute and blood thinner. Moreover, it's known to be biocompatible. PVP's chemistry makes it behave somewhat like soap.

HA-based coatings, on the other hand, form more of a hydrogel-type surface. This material is a long-chain polysaccharide that traps water and hence makes a very durable, pliable coating offering advantages in certain cases.

Here are three things Edwards thinks device designers should consider when deciding between the two coatings:

1. What do you need the coating to do?

Edwards says it is important to put into design inputs all of the parameters around what you want to see out of a coating, including lubricity and durability to hold up over whatever number of passes are needed with the device.

"Simple lubricity can be accomplished by both; more demanding applications may indicate a hydrogel is appropriate," Edwards says.

2. What is the pH of your test media?

"Buffered Saline is ideal as it mimics blood," Edwards says. "If you have DI water as a test media the pH is important as either too acid or basic solutions will give false readings for HA based coating performance."

3. What kind of sterilization are you using?

"Most coatings do not survive gamma or e-beam," Edwards says. "If you choose this method of sterilization, specify a coating that can demonstrate performance following sterilization."

Chris Newmarker is senior editor of Qmed and MPMN. Follow him on Twitter at @newmarker.

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