Self-assembled monolayers on gold for the fabrication of radioactive stents

An innovative and easily applicable method for the fabrication of radioacti ve stents, to be used for tile treatment of restenosis, is presented. By in corporating the beta -emitting radioisotopes Re-186,Re-188 Y-90, or P-32 in to sulfur-containing adsorbates, it becomes possible to cover a gold surfac e with a radioactive self-assembled monolayer (SAM). Two methods have been investigated. In the first, SAMs consisting of potentially radioactive rhen ium-, yttrium-, and phosphorus-containing adsorbates have been assembled on 2D gold substrates, after which they have been studied by wettability meas urements, electrochemistry, and X-ray photoelectron spectroscopy (XPS). The stability of these SAMs under simulated physiological conditions (phosphat e buffered saline, PBS solution) for periods up to two months has been demo nstrated. Alternatively, potentially radioactive monolayers have been prepa red by exposure of SAMs of mono-, bi-, and tridentate: ligands to a solutio n containing a radiometal (rhenium) in order to bind the metal to the monol ayer. The polydentate: ligands exhibit excellent binding capacity, leading to SAMs containing over 10(-10) mol/cm(2) of the radiometal, which is more than sufficient to make this system viable for the delivery of therapeutica l dosages of radiation.