Modified metal surface and method for preparing the same using an electrochemical process

Abstract

The present invention relates to a metal or alloy substrate having a modified surface, and more particularly a stainless steel substrate, produced by the use of an electrochemical process. The invention also relates generally to a method for producing a stable and covalent association between self-assembled layers and a surface of a metal substrate, and more particularly a stainless steel substrate. The metal or alloy substrate, and more particularly the stainless steel substrate, is modified by the covalent attachment of self-assembled monolayers on the surface by using an electrochemical process. These functionalized self-assembled monolayers provide a link to irreversibly attach or immobilize an active or nonactive agent.

1 . A method for attaching self-assembled monolayers onto a surface of a stainless steel substrate comprising contacting said surface with a solution comprising an alkanethiol compound, and electrochemically depositing said alkanethiol compound on the surface using a nickel-based alloy auxiliary electrode to covalently attach the self-assembly monolayers onto said surface. 
     
     
         2 . The method of  claim 1 , wherein the surface is pretreated by polishing said surface and/or etching said surface with oxalic acid. 
     
     
         3 . The method of  claim 1 , wherein the solution is an ionically-conductive aqueous or an ethanolic electrolyte solution. 
     
     
         4 . The method of  claim 1 , wherein the nickel-based alloy auxiliary electrode is a nichrome or a nickel auxiliary electrode. 
     
     
         5 . The method of  claim 1 , wherein the self-assembled monolayers are formed by a cyclic application of a polarization potential. 
     
     
         6 . The method of  claim 5 , wherein the polarization potential is between −1.8 volts and 0 volt vs. SCE (Saturated Calomel Electrode) and is applied for at least 25 cycles, preferably for 1 to 150 cycles. 
     
     
         7 . The method of  claim 1 , wherein the solution is preconditioned by a cyclic potentiodynamic polarization of a nickel-based alloy auxiliary and working electrode. 
     
     
         8 . The method of  claim 7 , wherein the polarization is performed at a scan rate of 100 mV/s between −1.8 volts and 0 volt vs. SCE for 50 to 400 cycles and for, preferably, 250 cycles. 
     
     
         9 . The method of  claim 1 , further comprising covalently attaching to an end group of the self-assembled monolayers a nonactive agent or an active agent selected from the group consisting of proteins, pharmaceuticals, drugs, polymers, antibodies, bioorganic molecules, biologically active agents, preferably fibronectin, and metal nanoparticles. 
     
     
         10 . The method of  claim 9 , wherein the end group of the self-assembled monolayers is chemically modified before covalently attaching the nonactive agent or the active agent. 
     
     
         11 . A method for attaching self-assembled monolayers onto a surface of a metal substrate comprising contacting said surface with a solution comprising an alkanethiol compound, and electrochemically depositing said alkanethiol compound on the surface using a nickel-based alloy auxiliary electrode to covalently attach the self-assembly monolayers onto said surface. 
     
     
         12 . The method of  claim 11 , wherein the substrate is nickel titanium (NiTi). 
     
     
         13 . The method of  claim 11 , wherein the substrate is cobalt-chrome alloy (CoCr). 
     
     
         14 . A stainless steel substrate having a modified surface comprising self-assembled monolayers covalently attached to the surface, wherein said self-assembled monolayers are prepared by contacting said surface with a solution comprising an alkanethiol compound, and electrochemically depositing said alkanethiol compound on the surface using a nickel-based alloy auxiliary electrode. 
     
     
         15 . The stainless steel substrate of  claim 14 , further comprising a nonactive agent or an active agent covalently attached to an end group of the self-assembled monolayers, the active agent being selected from the group consisting of proteins, pharmaceuticals, drugs, polymers, antibodies, bioorganic molecules, biologically active agents, preferably fibronectin, and metal nanoparticles. 
     
     
         16 . A metal substrate having a modified surface comprising self-assembled monolayers covalently attached to the metal surface, wherein said self-assembled monolayers are prepared by contacting said metal surface with a solution comprising an alkanethiol compound, and electrochemically depositing said alkanethiol compound on the metal surface using a nickel-based alloy auxiliary electrode. 
     
     
         17 . The metal substrate of  claim 16 , wherein the substrate is nickel titanium (NiTi). 
     
     
         18 . The metal substrate of  claim 16 , wherein the substrate is cobalt-chrome alloy (CoCr). 
     
     
         19 . The metal substrate of  claim 16 , further comprising a nonactive agent or an active agent covalently attached to an end group of the self-assembled monolayers, the active agent being selected from the group consisting of proteins, pharmaceuticals, drugs, polymers, antibodies, bioorganic molecules, biologically active agents, preferably fibronectin, and metal nanoparticles. 
     
     
         20 . A medical device having a metal substrate with a modified surface comprising self-assembled monolayers covalently attached to the metal surface, wherein said self-assembled monolayers are prepared by contacting said surface with a solution comprising an alkanethiol compound, and electrochemically depositing said alkanethiol compound on the surface using a nickel-based alloy auxiliary electrode.