Carboxyl-modified superabsorbent protein hydrogel

Abstract

The present invention is a biodegradable, reversibly-swellable, polyvalent cation-binding, protein hydrogel which comprises an acylated protein matrix in which the acylated protein matrix is crosslinked with a bifunctional crosslinking reagent, and treated with a polar organic solvent, and a method of making the same.

What is claimed is:  
     
         1 . A protein hydrogel comprising an acylated protein matrix, the acylated protein matrix being crosslinked with a bifunctional crosslinking reagent to yield a crosslinked protein matrix, the crosslinked protein matrix then being treated with a polar organic solvent.  
     
     
         2 . The protein hydrogel according to  claim 1 , wherein the bifunctional crosslinking agent is a bifunctional aldehyde.  
     
     
         3 . The protein hydrogel according to  claim 2 , wherein the bifunctional aldehyde is selected from the group consisting of  
       OCH—(CH2) x —CHO  
       wherein X is an integer of from 2 to 8.  
     
     
         4 . The protein hydrogel according to  claim 1 , wherein the bifunctional crosslinking agent is glutaraldehyde.  
     
     
         5 . The protein hydrogel according to  claim 1 , wherein the acylated protein matrix comprises a protein derived from biomass.  
     
     
         6 . The protein hydrogel according to  claim 1 , wherein the acylated protein matrix comprises a protein concentrate derived from biomass.  
     
     
         7 . The protein hydrogel according to  claim 1 , wherein the acylated protein matrix comprises a protein isolate derived from biomass.  
     
     
         8 . The protein hydrogel according to  claim 7 , wherein the protein isolate is a fish protein isolate.  
     
     
         9 . The protein hydrogel according to  claim 1 , wherein the acylated protein matrix is a protein treated with an acylating agent.  
     
     
         10 . The protein hydrogel according to  claim 9 , wherein the acylating agent is an anhydride.  
     
     
         11 . The protein hydrogel according to  claim 10 , wherein the acylating agent is a tetracarboxylic acid dianhydride.  
     
     
         12 . The protein hydrogel according to  claim 10 , wherein the acylating agent is ethylenediaminetetraacetic acid dianhydride.  
     
     
         13 . The protein hydrogel according to  claim 1 , wherein the polar organic solvent is selected from the group consisting of C 1 -C 4  alcohols, C 1 -C 4  ketones, and C 1 -C 4  aldehydes.  
     
     
         14 . The protein hydrogel according to  claim 13 , wherein the polar organic solvent is selected from the group consisting of ethanol, propanol, butanol, and acetone.  
     
     
         15 . The protein hydrogel according to  claim 14 , wherein the polar organic solvent comprises ethanol.  
     
     
         16 . A protein hydrogel comprising: 
 a fish protein isolate, the fish protein isolate being acylated by treatment with ethylenediaminetetraacetic acid dianhydride to yield an acylated protein;    the acylated protein being crosslinked with glutaraldehyde to yield a crosslinked protein matrix; and    the crosslinked protein matrix being treated with a polar organic solvent.    
     
     
         17 . A method of making a protein hydrogel, the method comprising the steps of: 
 (a) treating a protein with an acylating agent to yield an acylated protein;    (b) crosslinking the acylated protein with a bifunctional crosslinking agent to yield a crosslinked protein; and    (c) treating the crosslinked protein with a polar organic solvent.    
     
     
         18 . The method according to  claim 17 , wherein in step (a) the protein is treated with an amount of acylating agent sufficient to acylate from about 1 to about 98% of lysine residues within the protein.  
     
     
         19 . The method according to  claim 17 , wherein in step (a) the protein is treated with an anhydride.  
     
     
         20 . The method according to  claim 17 , wherein in step (a) the protein is treated with a tetracarboxylic acid dianhydride.  
     
     
         21 . The method according to  claim 20 , wherein in step (a) the protein is treated with ethylenediaminetetraacetic acid dianhydride.  
     
     
         22 . The method according to  claim 20 , wherein in step (b) the acylated protein is crosslinked with a dialdehyde.  
     
     
         23 . The method according to  claim 22 , wherein in step (b) the dialdehyde is selected from the group consisting of  
       OCH—(CH2) x —CHO  
       wherein X is an integer of from 2 to 8.  
     
     
         24 . The method according to  claim 23 , wherein in step (b) the dialdehyde is glutaraldehyde.  
     
     
         25 . The method according to  claim 17 , wherein: 
 in step (a) the acylating agent is added to an aqueous protein solution of about pH 12, at a temperature of about 65 to 100° C. to yield the acylated protein; and    in step (b) crosslinking is effected by addition of glutaraldehyde to an aqueous solution of the acylated protein of step (a) to yield a crosslinked protein; and    in step (c) the crosslinked protein is treated with a polar organic solvent selected from the group consisting of C 1 -C 4  alcohols, C 1 -C 4  ketones, and C 1 -C 4  aldehydes.    
     
     
         26 . The method according to  claim 25 , wherein in step (c) the crosslinked protein is treated with a polar organic solvent selected from the group consisting of ethanol, propanol, butanol, and acetone.  
     
     
         27 . The method according to  claim 26 , wherein in step (c) the crosslinked protein is treated with ethanol.