title: Biliary stent clogging solved by nanotechnology? In vitro study of inorganic-organic sol-gel coatings for teflon stents.
abstract: OBJECTIVE
  The major drawback of plastic stents for biliary drainage is the occlusion by sludge. 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. In this study, experience from nanotechnology to achieve a clean surface by improved soil-release characteristics is used to optimize biliary stent surface. The aim of this study was to examine sludge accumulation in relation to surface characteristics designed by nanotechnology.
  
  
  METHODS
  A variety of inorganic-organic sol-gel-coated stents were incubated in sterilized human bile and enzyme-active Escherichia coli for 35 days. Materials were Teflon (DuPont, Wilmington, DE) coated with hydrophobic Clearcoat (NTC, Tholey, Germany), Teflon with sol-gel coating synthesized of organic epoxides of 190 g/mol or 500 g/mol, and propylaminosilane without or with fluorsilanes for increased hydrophobicity. Scanning electron microscopy and semiquantitative analysis, blinded to the type of coating, were used to determine the amount of sludge accumulated on the surface.
  
  
  RESULTS
  Sludge deposition was reduced on the designed surfaces as compared with uncoated Teflon and Clearcoat. The performance of high molecular (500 g/mol) was superior to that of low molecular (190 g/mol) epoxide ligand. However, increasing hydrophobicity by adding fluoraminosilanes resulted in increased adherence of sludge. Less than a micrometer-thin sol-gel coating is inexpensive because very little coating material is required. This is the first published data comparing systematically modified surfaces of biliary stents using nanotechnology.
  
  
  CONCLUSIONS
  Optimized soil release by sol-gel nanocoating of plastic stents may prevent biliary plastic stents from clogging.
authors.affiliation: Department of Interdisciplinary Endoscopy, University Medical Center Eppendorf, Hamburg, Gernany. seitz@uke.uni-hamburg.de <seitz@uke.uni-hamburg.de>
authors.forename: Uwe
authors.initials: U
authors.lastname: Seitz
authors.forename: Andreas
authors.initials: A
authors.lastname: Block
authors.forename: Ann-Christina
authors.initials: AC
authors.lastname: Schaefer
authors.forename: Uwe
authors.initials: U
authors.lastname: Wienhold
authors.forename: Sabine
authors.initials: S
authors.lastname: Bohnacker
authors.forename: Klaus
authors.initials: K
authors.lastname: Siebert
authors.forename: Stefan
authors.initials: S
authors.lastname: Seewald
authors.forename: Frank
authors.initials: F
authors.lastname: Thonke
authors.forename: Holger
authors.initials: H
authors.lastname: Wulff
authors.forename: Andreas
authors.initials: A
authors.lastname: De Weerth
authors.forename: Nib
authors.initials: N
authors.lastname: Soehendra
mesh_terms: D001646:Bile; D001659:Biliary Tract; D020099:Coated Materials, Biocompatible / Q000138:chemical synthesis*; D004852:Epoxy Compounds / Q000138:chemical synthesis; D004867:Equipment Design; D004926:Escherichia coli / Q000201:enzymology; D005782:Gels; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D066298:In Vitro Techniques; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D036103:Nanotechnology / Q000379:methods*; D011138:Polytetrafluoroethylene; D012821:Silanes / Q000138:chemical synthesis; D015607:Stents / Q000382:microbiology
chemical_list: D020099:Coated Materials, Biocompatible; D004852:Epoxy Compounds; D005782:Gels; D012821:Silanes; D011138:Polytetrafluoroethylene