Methods for cross-linking bioprosthetic tissue using bio-orthogonal binding pairs

Abstract

Methods for treating a bioprosthetic tissue are described. The methods comprise contacting the biological tissue with an anchor compound, the anchor compound comprising first and second functional groups. The first functional group is reactive with and couples a tissue functional group associated with the biological tissue. The second functional group is one of a bio-orthogonal binding pair. The biological tissue coupled to the anchor compound is then exposed to a linking compound. The linking compound comprises at least two functional groups, each comprising the other one of the bio-orthogonal binding pair. In a preferred embodiment, the bio-orthogonal binding pair is an azide and an acetylene. The method can be performed in the presence of a catalyst, preferably a copper catalyst. Alternatively, the method can be performed in the absence of a catalyst, wherein the acetylene is incorporated in a ring-strained cyclic compound, such as cyclooctyne.

What is claimed is: 
     
         1 . A method for cross-linking biological tissue comprising:
 contacting the biological tissue with an anchor compound, the anchor compound comprising first and second functional groups, the first functional group coupling a tissue functional group associated with the biological tissue and the second functional group being one of a bio-orthogonal binding pair; and   exposing the biological tissue to a linking compound, the linking compound comprising at least two functional groups, the two functional groups each comprising the other one of the bio-orthogonal binding pair.   
     
     
         2 . The method of  claim 1 , wherein the bio-orthogonal binding pair comprises an azide and an acetylene. 
     
     
         3 . The method of  claim 2 , wherein the exposing is performed in the presence of a catalyst. 
     
     
         4 . The method of  claim 3 , wherein the catalyst is a copper. 
     
     
         5 . The method of  claim 4 , further comprising rinsing the biological tissue after the exposing. 
     
     
         6 . The method of  claim 2 , wherein the acetylene is incorporated in a cyclic compound having a ring strain. 
     
     
         7 . The method of  claim 6 , wherein the acetylene is a cyclooctyne. 
     
     
         8 . The method of  claim 7 , wherein cyclooctyne comprises one or more electron-withdrawing groups. 
     
     
         9 . The method of  claim 8 , wherein the electron-withdrawing group is a halogen. 
     
     
         10 . The method of  claim 9 , wherein the electron-withdrawing group is a fluorine. 
     
     
         11 . The method of  claim 9 , wherein the exposing is performed in the absence of a catalyst. 
     
     
         12 . The method of  claim 1 , wherein the tissue functional group is one or more selected from the group consisting of an amine, a hydroxyl, a sulfhydryl, a carbonyl, and a carboxylic acid. 
     
     
         13 . The method of  claim 12 , wherein the tissue functional group is an amine. 
     
     
         14 . The method of  claim 13 , wherein the first functional group is an aldehyde. 
     
     
         15 . The method of  claim 1 , wherein the first functional group of the anchor compound is selected from the group consisting of an isothiocyanate, an isocyanate, a sulfonyl chloride, an aldehyde, a carbodiimide, an acyl azide, an anhydride, a fluorobenzene, a carbonate, an N-Hydroxysuccinimides (NHS), an NHS ester, an imidoester, an epoxide, and a fluorophenyl ester. 
     
     
         16 . The method of  claim 1 , wherein the anchor compound is one or a combination of an imidazole-1-sulfonyl azide and trifluoromethanesulfonyl azide. 
     
     
         17 . The method of  claim 1 , wherein either one or both of the anchor and the linking compounds comprises a spacer. 
     
     
         18 . The method of  claim 17 , wherein the spacer does not comprise functional groups that are reactive with the biological tissue, the tissue functional group or any one of the bio-orthogonal binding pair. 
     
     
         19 . The method of  claim 17 , wherein the linking compound comprises the spacer. 
     
     
         20 . The method of  claim 17 , wherein the spacer is one or a combination selected from branched or straight-chain saturated or unsaturated hydrocarbons and a polymer. 
     
     
         21 . The method of  claim 17 , wherein the spacer comprises one or a combination of a bioactive and a biodegradable group. 
     
     
         22 . The method of  claim 21 , wherein the spacer comprises a biodegradable group and wherein the biodegradable group is a disulfide. 
     
     
         23 . A cross-linked bioprosthetic tissue produced in accordance with the method of  claim 1 .