Controlled vapor deposition of biocompatible coatings for medical devices

Abstract

We have developed an improved vapor-phase deposition method and apparatus for the application of layers and coatings on various substrates. The method and apparatus are useful in the fabrication of biofunctional devices, Bio-MEMS devices, and in the fabrication of microfluidic devices for biological applications. In one important embodiment, oxide/polyethylene glycol coatings provide increased hydrophilicity and improved biocompatibility for medical devices and implants.

1 . A method of depositing a biocompatible coating on a substrate, wherein a surface of said substrate is vapor deposition coated, wherein at least one coating layer or a portion of a coating layer deposited on said surface is deposited using a stagnation reaction step, and wherein a polyethylene glycol/polyethylene oxide-comprising precursor is reacted to form at least one coating layer or a portion of a coating layer.  
     
     
         2 . A method in accordance with  claim 1 , wherein said polyethylene glycol/polyethylene oxide-comprising precursor is reacted to form a biocompatible coating which provides a hydrophilicity which is related to a surface tension of a biological fluid.  
     
     
         3 . A method in accordance with  claim 2 , wherein said substrate forms at least one surface of a device which is intended for temporary use within or adjacent to tissue of a mammal.  
     
     
         4 . A method in accordance with  claim 3 , wherein said device is a contact lens or a catheter.  
     
     
         5 . A method in accordance with  claim 2 , wherein said substrate forms at least one surface of a device which is intended for implantation within a body, which implantation lasts for a period of at least one year.  
     
     
         6 . A method in accordance with  claim 5 , wherein said device is selected from the group consisting of an intra-ocular lens, a synthetic blood vessel, a synthetic heart valve, a stent, a joint replacement, a bone replacement, and a breast implant.  
     
     
         7 . A method in accordance with  claim 1 , wherein said biocompatible vapor-deposited coating includes at least one oxide-based layer and at least one organic functional layer, and wherein said at least one organic functional layer includes a surface layer which is generated from said polyethylene glycol-comprising precursor.  
     
     
         8 . A method in accordance with  claim 7 , wherein said surface layer of said vapor-deposited coating exhibits a DI water wetting angle ranging from about 5° to about 90°.  
     
     
         9 . A method in accordance with  claim 8 , wherein said surface layer of said vapor-deposited coating exhibits a DI water wetting angle ranging from about 15° to about 60°.  
     
     
         10 . A method in accordance with  claim 9 , wherein said surface layer of said vapor-deposited coating exhibits a DI water wetting angle ranging from about 25° to about 45°.  
     
     
         11 . A method in accordance with  claim 1 , wherein said method comprises the steps of: 
 a) exposing said surface of said substrate to an oxygen-comprising plasma in a processing chamber which is at subatmospheric pressure;    b) subsequently, without exposure of said oxygen-comprising plasma treated surface to ambient conditions which contaminate or react with said plasma treated surface, exposing said surface to a silicon chloride containing vapor in the presence of moisture, to form a hydrophilic silicon oxide layer on said surface;    c) subsequently, without exposure of said hydrophilic silicon oxide layer to ambient conditions which contaminate or react with said hydrophilic silicon oxide layer, exposing said silicon oxide layer to a functionalized silane precursor vapor containing polyethylene glycol/polyethylene oxide-comprising functional groups, to form a layer selected from the group consisting of a monolayer, a self-aligned monolayer, and a polymerized cross-linked layer.    
     
     
         12 . A method in accordance with  claim 11 , including an additional step: 
 d) repeating steps a) through c), or repeating steps b) through c), or repeating step c) a nominal number of times, without exposing said substrate to ambient conditions.    
     
     
         13 . A method in accordance with  claim 11 , wherein said subatmospheric pressure during step a) ranges from about 0.01 Torr to about 1 Torr.  
     
     
         14 . A method in accordance with  claim 11 , wherein said silicon chloride-containing precursor in step b) is silicon tetrachloride.  
     
     
         15 . A method in accordance with  claim 1 , wherein said method comprises the steps of: 
 a) exposing said surface of said substrate to a silicon chloride containing vapor in the presence of moisture, to form a hydrophilic Si x O y  layer is produced on said surface; and    b) subsequently, without exposure of said hydrophilic silicon oxide layer to ambient conditions which contaminate or react with said hydrophilic Si x O y  layer, exposing said Si x O y  layer to a functionalized silane precursor vapor containing polyethylene glycol/polyethylene oxide-comprising functional groups, to form a layer selected from the group consisting of a monolayer, a self-aligned monolayer, and a polymerized cross-linked layer.    
     
     
         16 . A method in accordance with  claim 15 , including an additional step: 
 c) repeating steps a) through b), or repeating step b) a nominal number of times, without exposing said substrate to ambient conditions.    
     
     
         17 . A method in accordance with  claim 15 , wherein said silicon chloride-containing precursor in step a) is silicon tetrachloride.  
     
     
         18 . A method in accordance with  claim 11 , wherein an individual layer of said biocompatible coating is formed by repeating a given step a nominal number of times.  
     
     
         19 . A method in accordance with  claim 18 , wherein said individual layer is a Si x O y —containing layer.  
     
     
         20 . A method in accordance with  claim 18 , wherein said individual layer is a polyethylene glycol/polyethylene oxide-containing layer.  
     
     
         21 . A method in accordance with  claim 15 , wherein an individual layer of said biocompatible coating is formed by repeating a given step a nominal number of times.  
     
     
         22 . A method in accordance with  claim 21 , wherein said individual layer is a Si x O y —containing layer.  
     
     
         23 . A method in accordance with  claim 21 , wherein said individual layer is a polyethylene glycol/polyethylene oxide-containing layer.