title: Electrochemical etching of micro-pores in medical grade cobalt-chromium alloy as reservoirs for drug eluting stents.
abstract: Drug eluting stents (DES) have shown efficacy in reducing restenosis after angioplasty followed by application of a coronary stent. However, polymer matrices typically used for immobilizing drugs on the stent surface may cause irritation and have limited drug loading capacity. In contrast, drug loading into micro- or nanopores created within the stent material could avoid these problems. We present a technology based on electrochemically induced pitting corrosion to form pores in medical grade steel, followed by loading with rapamycin. This process is applied to pore formation and drug loading in coronary stents consisting of L605 medical steel. Sustained release of the drug over 28 days at rates comparable to established DES was demonstrated. This technology is capable of creating pores with well-defined pore size and filling of these pores by a drug employing a crystallization process thus completely avoiding polymer matrices to immobilize drugs. Electrochemically induced pitting corrosion provides a generic means to introduce micro-pores suitable as drug reservoirs into medical grade steel without the need for any further matrix material. Further research will expand these findings to other materials and types of implants that could benefit from the additional function of drug release and/or improved implant/tissue integration.
authors.affiliation: NMI Natural and Medical Sciences Institute at the University of Tübingen, Reutlingen, Germany.
authors.forename: Kai
authors.initials: K
authors.lastname: Fuchsberger
authors.affiliation: NMI Natural and Medical Sciences Institute at the University of Tübingen, Reutlingen, Germany.
authors.forename: Karoline
authors.initials: K
authors.lastname: Binder
authors.affiliation: NMI Natural and Medical Sciences Institute at the University of Tübingen, Reutlingen, Germany.
authors.forename: Claus
authors.initials: C
authors.lastname: Burkhardt
authors.affiliation: NMI Natural and Medical Sciences Institute at the University of Tübingen, Reutlingen, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Freudigmann
authors.affiliation: NMI Natural and Medical Sciences Institute at the University of Tübingen, Reutlingen, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Herrmann
authors.affiliation: NMI Natural and Medical Sciences Institute at the University of Tübingen, Reutlingen, Germany. martin.stelzle@nmi.de.
authors.forename: Martin
authors.identifier: http://orcid.org/0000-0003-2612-2359
authors.initials: M
authors.lastname: Stelzle
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry; D002858:Chromium Alloys / Q000737:chemistry*; D054855:Drug-Eluting Stents; D055664:Electrochemical Techniques; D007700:Kinetics; D008422:Materials Testing; D011474:Prosthesis Design; D020123:Sirolimus / Q000737:chemistry
chemical_list: D000900:Anti-Bacterial Agents; D002858:Chromium Alloys; D020123:Sirolimus