Plasma Treatment for Adhesion of Lubricious Hydrophilic coatings

Posted by Josh Simon on Mon, Nov 28, 2011 @ 09:18

Today's article comes to us from Drs. Demetrius Chrysostomou and James Bond from PVATepla.  It is an informative read on plasma treatment for hydrophilic coatings:

Catheters are inserted into the body for fluid drainage, duct dilation and drug/nutrient delivery.  With an invasive device the host’s health can be compromised due to tissue trauma and subsequent infection. Hydrophilic coatings are beneficial in reducing trauma damage. However, some catheter polymers can be classified ‘difficult to coat’ and the adhesion is far from optimal.  Good adhesion of the hydrophilic coating is essential. Poor adhesion could lead to shedding of the coating in vivo and increase the risk of coronary embolism.    This is where plasma can play an important role

What is plasma?

plasma

Plasma is a gas energized to a state of electrical conductivity. Chemically it is a highly reactive environment that is used to change the properties of surfaces without affecting the bulk material. Plasma is a powerful tool in solving surface preparation problems such as precision cleaning and decontamination, increasing surface wettability and adhesion promotion of functional bio-molecules and coatings. Plasma can also be used to polymerize coatings onto surfaces through a technique called Plasma Enhanced Chemical Vapor Deposition (PECVD). The main advantage of plasma as an enabling technology is that it is a clean dry process. As such there are none of the liabilities of wet chemistry, such as leaching toxic solvents.

Historical use of Primers for Surface Activation

Historically primers have been used to activate ‘difficult polymer’ surfaces. Some primers are considered hazardous.  There may be primers are highly toxic, caustic, carcinogenic and are potential leachables. The EPA and FDA review medical grade primers and the trend is to remove particular primers from the ‘safe to use list’. An example of the chemical primer used for PTFE and ePTFE is TetraEtch (a mixture of sodium, naphthalene and 1,2 – dimethoxyethane). This primer is teratogenic, toxic and caustic.  

plasma schematic

Plasma prepares the surface by molecular cleaning.  Specific chemical groups are then grafted by a second plasma step.  The surface is then exposed to the functional molecules that chemically bind to the plasma grafted moieties.

ePTFE use for medical devices

Expanded polytetrafluoroethylene (ePTFE) is a commonly used material for implant applications. It’s mechanical strength, impermeability to blood and inertness to bio fouling make ePTFE ideal for such in-vivo applications. Its flexibility aids in healing, and catheter tubing doesn’t kink very easily and generally has good compression resistance. For biomedical applications the ability to modify PTFE surfaces is important to promote interfacial biocompatibility.

 

Plasma treatment of ePTFE for binding lubricous coatings

 It is possible to graft polar functional groups to PTFE by plasma activation. These polar functional groups act as excellent anchor to covalently bond hydrophilic coatings. The PVA TePla plasma surface activation for ePTFE is an environmentally friendly alternative to primer treatment. We treat parts in a highly controlled low temperature, low pressure dry, clean gas environment such as the IoN300 catheter treating tool below.  

plasma machine

What does PVA TePla America offer?

 PVA TePla America offers a solutions based team of chemists (physical, surface, organic and bio-chemist) who will work with you or your chosen coatings company to find the very best surface treatment for you polymer. We offer free proof of process as an incentive to evaluate our plasma technology. We have clean area contract processing capability with ISO 9001:2008 certification. And we offer a full range of vacuum and atmospheric gas plasma systems. PVA TePla America is based in Corona, CA. www.pvateplaamerica.com

 

For further information contact  jamesb@pvateplaamerica.com (951) 415-0391

 

 

 

 

 

 

Tags: coating equipment, PVATepla, lubricious coatings, hydrophilic coating on teflon, plasma treatment

Bayer Boosts Coatings Presence in China

Posted by Josh Simon on Wed, Nov 23, 2011 @ 10:38

I found an interesting article talking about Bayer's coating business and its increased focus on the Chinese market.  Let me point out that the business of "coatings" is gigantic and comprises everything from paint, to industrial coatings, aerospace surfaces, and yes, even medical device coatings.  In this article, Bayer is talking about moving a multiple hundreds of million (perhaps over a billion?) dollar operation in a market just as large.

By contrast, hydrophilic coatings are an almost infintesimally small part of the overall business of "coatings".  Bayer does indeed have a hydrophilic coating it obtained when it bought the business from Lombard Medical. However, I am not sure that Bayer yet realizes that this market is infintesimally small compared to its other businesses. 

In my guestimation, the entire market for hydrophilic coatings, in the world, is not over $120 million.  (Although it is definitely growing fast.)  You have to remember, this is not medical device revenue.  This is revenue for hydrophilic coatings sold to the medical device companies that eventually put them on products.  Effectively, what a hydrophilic coating company sells is a "bottle of stuff", or a "bottle of goo", as Peg Palmer is often fond of saying.  How much money you can get for goo is limited to whatever license fees, royalties, or direct revenue you can get for it.  Unless you capture the entire market, your realistic expectations are likely to be smaller than the rounding error of one of Bayer's typical products.

 

Click me

 

Tags: Hydrophilic Coating, coatings companies, coatings vendor, coating company, coating manufacturer, industrial coating, Coatings2Go, hydrophilic coating market, coatings manufacturer, coatings supplier, non-medical coating, industrial coatings, Bayer

Implantable Hydrophilic Coatings

Posted by Josh Simon on Mon, Nov 21, 2011 @ 03:59

In a previous blog post on permanent hydrophilic coatings, I noted that really all hydrophilic coatings have some sort of bioerosion, degradation, and/or resorption rates in vivo.  For most coatings of this nature, those rates are high, which means they are not always suitable for implantation.

Honestly, that's a rather broad and general statement about the utility of implantable hydrophilic coatings.  In reality it goes back to a question I like to ask a lot on this blog:  What is your application?

Let me break that out into some more specific thought questions:

What kind of device do you want to coat?

WHY do you want to coat it?

Do you want it to be slippery?  Non-thrombogenic?  Closely associated with water to prevent fogging or misting?

Given your answer to the question above, exactly WHEN do you want the coating to possess those properties during the life of the device?  Pre-implantation? During implantation?  During explantation?  The whole time?

Given that last answer, how long is that time period?  Minutes?  Hours?  Days?  Weeks?  Forever?

In many cases, for example in the case of an implantable cardiac pacemaker, surgeons may be complaining that it is difficult to squish the leads into place during the procedure.  A lubricious coating might help with that.  However, once the device is implanted, who cares about what happens to the coating as long as it is biocompatible?  Or maybe I should ask:  do you care what happens?

If you do care, then you need to ask yourself why.  Is there some other function a slippery, non-thrombogenic, water-loving coating will serve a purpose after implanting that pacemaker?

Most of the time, when clients come to me asking for permanent hydrophilic coatings, it actually turns out that they do not need them to be permanent.  They just need them to fulfil a temporary role, which the coating can do easily, and then when it goes away it is of no consequence.

 

Click me

Tags: advanced coating, lubricious coating, medical device coating, Hydrophilic Coating, biomaterials, hydrophilic coatings, lubricious coatings, non-thrombogenic coating

Hydrophilic Coatings at MDM Minneapolis 2011

Posted by Josh Simon on Wed, Nov 09, 2011 @ 02:56

The guys at Medical Design Technology filmed me while I was at our booth for the MDM Minneapolis show this past week giving a lubricious hydrophilic coating demonstration.

 

I want to especially thank Mr. Sean Fenske, Editor-In-Chief at MDT magazine for doing this.

Tags: lubricious coating, Hydrophilic Coating, hydrophilic coatings, coating video