Self-Assembled Monolayers on Gold for the Fabrication of Radioactive Stents

Abstract

An innovative and easily applicable method for the fabrication of radioactive stents, to be used for the treatment of restenosis, is presented. By incorporating the β‐emitting radioisotopes 186Re, 188Re, 90Y, or 32P into sulfur‐containing adsorbates, it becomes possible to cover a gold surface with a radioactive self‐assembled monolayer (SAM). Two methods have been investigated. In the first, SAMs consisting of potentially radioactive rhenium‐, yttrium‐, and phosphorus‐containing adsorbates have been assembled on 2D gold substrates, after which they have been studied by wettability measurements, electrochemistry, and X‐ray photoelectron spectroscopy (XPS). The stability of these SAMs under simulated physiological conditions (phosphate buffered saline, PBS solution) for periods up to two months has been demonstrated. Alternatively, potentially radioactive monolayers have been prepared by exposure of SAMs of mono‐, bi‐, and tridentate ligands to a solution containing a radiometal (rhenium) in order to bind the metal to the monolayer. The polydentate ligands exhibit excellent binding capacity, leading to SAMs containing over 10–10 mol/cm2 of the radiometal, which is more than sufficient to make this system viable for the delivery of therapeutical dosages of radiation.

Microfabrication and nanotechnology in stent design

“…83 Self-assembled monolayers (SAMs) form highly ordered monolayers a few nanometers thick and facilitate the presentation of a variety of unique chemical groups, including those that chelate radioisotopes. 84 SAMs can persist on a stainless steel stent for 14-21 days before oxidation and desorption of the thin film from the stent. 85 As a variant of film deposition strategies based on molecular selfassembly, Stupp and colleagues have described the deposition of self-assembled peptide nanofibers to enhance cell adhesion and proliferation.…”

“…DNA loaded into an LbL film has been successfully transferred from a stent into the vascular wall 83. Self‐assembled monolayers (SAMs) form highly ordered monolayers a few nanometers thick and facilitate the presentation of a variety of unique chemical groups, including those that chelate radioisotopes 84. SAMs can persist on a stainless steel stent for 14–21 days before oxidation and desorption of the thin film from the stent 85.…”

Self-assembled monolayers of thiols and dithiols on gold: new challenges for a well-known system

“…47 In the field of biomedicine, thiol and dithiol SAMs are used as linkers or protective groups for biomolecule carriers (e.g., for drug delivery purposes), 48 and also to functionalize the surface of medical devices such as gold stents. 37,49 Other applications of these SAMs include their use as chemical templates for crystallization of inorganic salts. 50,51 Self-assembled monolayers have been studied by many different and complementary surface science techniques, both in situ (in the environment where the monolayers were formed) and ex situ (in a different environment, normally air).…”

Electrochemical characterization of vascular bare-metal stents. A novel approach modifying the mini-cell system

“…org | volume 1: issue 1 microscopically identify surface alterations associated with corrosion under biological conditions [3]. Immersion testing was performed to investigate the corrosion properties of stents or stent materials [4], and has frequently been combined with other analysis techniques, such as open circuit potential (OCP) measurements, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS) [5][6][7][8][9][10][11][12]. Applications of in vitro corrosion analyses include the characterization of surface modifications [9,11,13,14], coatings [5,8,10,12,15,16] and new materials [6,17,18].…”