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Nano-Coating of Biliary Stents Prevents Clogging

NEW YORK (Reuters Health) Sept 03 - 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.