Study on the synthesis and properties of mussel mimetic poly(ethylene glycol) bioadhesive

The catecholic amino acid 3,4-Dihydroxyphenyl- l -alanine (DOPA) is believed to be responsible for the water-resistant adhesive characteristics of mussel adhesive proteins (MAPs). In this paper, the synthesis of three-armed poly(ethylene glycol)s with dopamine endgroups (PEG–DOPAs) using acylation reaction and Michael addition reaction was described, and PEG–DOPAs was used as bioadhesive under the UV irradiation. The structures of PEG–DOPAs were characterized by FTIR, 1 H NMR spectroscopy. The adhesion properties of PEG–DOPAs were investigated and results were significantly superior to 0.05   MPa of the commercially available fibrin adhesives. Moreover, the adhesive strength of PEG–DOPAs (Mw 3000) increased from 0.587   MPa to 1.82   MPa, PEG–DOPAs (Mw 20,000) increased from 0.338   MPa to 1.92   MPa with the elongation of the binding time, severally. The photopolymerization kinetic study was taken to evaluate gelation time of bioadhesive indirectly. The cytotoxicity of photocured PEG–DOPAs hydrogels for L929 cells was evaluated by the fluorescence microscopy and MTT (3-[4-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide; Thiazolyl blue) assay, respectively. The results showed that PEG–DOPAs were biocompatible and less cytotoxicity toward the growth of L929 cells. The swelling properties of PEG–DOPAs hydrogels were also tested. PEG–DOPAs (3000) reached swelling equilibrium within 2   h at 37   °C, and PEG–DOPAs (20,000) within 6   h at 37   °C.