Drug & Device Development

Nano-coating of biliary stents prevents clogging

Last Updated: 2007-09-03 8:30:22 -0400 (Reuters Health)

NEW YORK (Reuters Health) - The common problem of biliary stent blockage can be settled by using nanotechnology to design surface characteristics that prevent build-up of "sludge" and thus keep the stent open, scientists in Germany report.

"Sludge is accrued because the stent surface allows for the adherence of proteins, glycoproteins, or bacteria and the bile flow is insufficient to clean the surface," Dr. Uwe Seitz and associates explain in the August issue of Gastroenterology.

They developed several "sol-gel" coatings, "created by chemical reaction of an organic epoxide with an inorganic silane and subsequent polymerization by adding a catalyst." Teflon-coated plastic stents were dipped into the different sol-gel liquids and air-dried, producing a nanometer-thin layer that reduces adhesion of any part of sludge or biofilm.

Dr. Seitz, from the University Medical Center Eppendorf in Hamburg, and associates tested seven different coatings by incubating the "nano-coated" Teflon stents in sterilized human bile and enzyme-active Escherichia coli for 35 days.

Based on scanning electron microscopy, sludge deposition was reduced by the sol-gel coated surfaces as compared to the amount deposited with uncoated Teflon. The most effective coating consisted of a combination of a high molecular epoxide and propylaminosilane.

While warning that the results of their in vitro study may not translate into clinical settings, Dr. Seitz and associates propose that "the development of inexpensive plastic biliary stents (will allow) a longer patency associated with less discomfort for patients."

This nanotechnology may also be suitable for other applications, the investigators suggest, such as urine catheters and intrauterine pessaries.

Gastroenterology 2007;133:65-71.