Chemical Crosslinking of Collagen

Physical gels based on collagen present interchain connections such as hydrogen bonds, hydrophobic interaction or van der Waals bonds. The preparation method for a physical gel requires heat to induce movement of molecules, which, in this way, will be able to form an ordered crystalline structure. 

Treatment with GTA is a commercially viable process, its efficiency has been optimized, it is inexpensive and completed in a relatively short period and provides more sustained long-term durability than crosslinking with formaldehyde [59,55], 

As an alternative to aldehyde treatment, strong and resistant collagen material can be obtained using hexamethylendiisocyanate as a crosslinker [55], 

The epoxy functionality from ethylene glycol diglycidyl ether, glycerol polyglycidyl ether and methylglycidyl ether predominantly reacts with the amino groups on lysine, much like GTA. 

Crosslinking with carbodiimides, especially l-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC), offers the main advantage over aldehydes or epoxy compounds in that these carbodiimides only facilitate the formation of amide bonds between carboxylic and amino groups on the collagen molecules without becoming part of the actual linkage. 

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The effectiveness of UV and chemical crosslinking of collagen membranes as dermal dressings has been evaluated by measuring their mechanical properties and resistance to collagenase as good indicators of the fabrication process [60]. 

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