In situ hydrogelation and RGD conjugation of tyramine-conjugated 4-arm PPO-PEO block copolymer for injectable bio-mimetic scaffolds

Abstract

RGD-conjugated Tetronic-tyramine (RGD-Tet-TA) hydrogels were formed in situ, and cell attachment and spreading on the hydrogels were evaluated for an injectable tissue-regenerative scaffold. The hydrogels were prepared by simple mixing GRGDGGGGGY (RGD-Y) in a tyramine-conjugated Tetronic (Tet-TA) polymer solution in the presence of horseradish peroxidase (HRP) and hydrogen peroxide (H2O2). The physico-chemical properties such as mechanical properties and swelling ratio were evaluated and the conjugated RGD concentration and distribution were measured using fluoresamine assay and fluorescence observation. An in vitro cell study was investigated using osteoblasts (MC3T3-E1) on the hydrogel surfaces for 24 h, in which the viability and morphology of the adhered cells were observed using live/dead and F-actin assays. The results demonstrate that the in situ conjugation of RGD peptides to tyrosine residues enhanced the attachment and spreading of osteoblasts in a surface density-dependent manner. Therefore, this study suggests that in situ conjugation of the RGD peptide to injectable hydrogels via an enzymatic reaction may be an efficient tool to prepare in situ forming bio-mimetic hydrogels for tissue regenerative medicine.