Table 1 Mechanism, advantages, and disadvantages of typical crosslinking methods

GA

Nucleophilic addition reaction between aldehyde groups in GA and amino groups in amino acid residues

Easy to use, low cost, low biodegradation, good biocompatibility and antithrombogenic, while maintaining integrity, strength, and elasticity; highest crosslinking degree and crosslinking stability among the three methods

The residual aldehyde groups are cytotoxic, which is not conducive to cell adhesion, growth, and endothelialization; they are also negatively-charged, which can lead to the adsorption of calcium ions, formation of calcium nuclei, and ultimately calcification

[85, 109,110,111,112]

BDDGE

The epoxy groups in BDDGE react with amino or carboxyl groups on collagen

The reaction is simple, mild, and efficient. The crosslinked tissue is lighter, whiter, and softer than GA. The inflammatory response is milder than GA

The crosslinking effect is not as good as that of GA. Resistance to degradation is slightly lower than GA, but is better than self-crosslinking

[113,114,115]

Self-crosslinking

Usually catalyzed by EDC and NHS, which can activate carboxyl groups on collagen, causing them to react with amino groups to form amide bonds

It requires mild reaction conditions, short reaction time, stable reaction products, and resists calcification. There are no residual crosslinking agents and no cytotoxicity issues

Compared to those of GA and BDDGE, self-crosslinking has the weakest crosslinking effect

[48, 116,117,118,119,120,121]