Enzymatic cross-linking
of polymer–catechol conjugates in
the presence of horseradish peroxidase (HRP) and H2O2 has emerged as an important method to fabricate in
situ-forming, injectable hydrogels. Subsequently, tissue
adhesion studies using catechol-containing polymers were extensively
reported. However, because of the presence of numerous variables such
as polymer concentration, oxidizing agent/enzyme, and stoichiometry,
the design of the polymer with optimized tissue adhesive property
is still challenging. In this study, a poly(γ-glutamic acid)
(γ-PGA)-dopamine (PGADA) conjugate was synthesized, and in situ hydrogels were fabricated via enzymatic
cross-linking of a catechol moiety. To optimize the tissue adhesive
property of the PGADA hydrogel, the effect of various factors, such
as polymer concentration, catechol substitution degree (DS), HRP concentration,
and H2O2 content, on the gelation behavior and
mechanical strength was investigated. The gelation behavior of PGADA
hydrogels was characterized using a rheometer and rotational viscometer.
Also, the possibility of its use as a tissue adhesive was examined
by evaluating the tissue adhesion strength in vitro and ex vivo.