writer：Junxia Hou, Chong Li, Ying Guan,* Yongjun Zhang* and X. X. Zhu*
keywords：hydrogel
source：期刊
specific source：Polymer Chemistry, 2015, 6(12), 2204-2213
Issue time：2015年

Enzymatic crosslinking of polymer-phenol conjugates in the presence of horseradish peroxidase (HRP) and H2O2 has emerged as an important method to synthesize in situ-forming, injectable hydrogels. Here we show alginate-dopamine (Alg-DA) conjugate, a polymer with catechol side groups instead of phenol groups, also gels in situ in the presence of HRP and H2O2. The effects of various factors, including the concentration of HRP, H2O2, and the polymer, and the degree of substitution of the polymer, on gelation rate and the mechanical strength of the resulting gels, were studied by rheology. The influences of these factors on the gelling of catechol-functionalized polymer are similar to their influences on phenol-functionalized polymers, suggesting they have a similar crosslinking mechanism. Compared to phenol-functionalized alginate-tyramine (Alg-TA) hydrogel, catechol-functionalized Alg-DA gels exhibit significantly improved adhesion properties. When both polymers have a degree of substitution of 10%, the adhesion strength of the latter is about 10-fold of the former. Replacement of phenol groups with catechol groups also results in very different cell behaviours. While the cells seeded on Alg-TA gels do not attach on the substratum, they attach on Alg-DA gels and exhibit a spread morphology. The significantly enhanced adhesion properties of Alg-DA hydrogels are attributed to the catechol moieties, a structure found in the adhesive proteins of blue mussels.