Mussel inspired bio-adhesive with multi-interactions for tissue repair

Bio-adhesives based on biopolymers have been widely researched for tissue repair. However, the adhesive properties are still insufficient to meet the practical applications. Introducing functional groups into the polymer chains that have multi-interactions among inter/intra-molecules and with substrates is an efficient way to increase cohesion force and further improve the adhesive properties. In this study, 3,4-dihydroxyphenyl propionic acid (DPA) and dopamine (DA) containing adhesion functional catechol groups were employed to modify chitosan (CS) and γ-polyglutamic acid (γPGA), respectively. The substituted degrees of the catechol groups were controlled by the catechol compositions. DPA modified chitosan/DA modified γPGA (CS-DPA/γPGA-DA) adhesives prepared by mixing CS-DPA and γPGA-DA. Effects of the substituted degrees and substrates on the adhesion strength were measured by tensile testing machine. The results showed good adhesion property of the CS-DPA/γPGA-DA adhesive on many surfaces of the substrates. Especially on the arthrodial cartilage, the adhesive strength reached around 150 kPa, much higher than commercially available tissue adhesives. The high adhesion property might be due to the adhesion interactions between the catechol groups and substrates and the high cohesion forces induced by the crosslinking interactions formation among the catechol groups and the electrostatic interactions between the CS and γPGA polymers. In vitro experiments demonstrated that the adhesive had good biocompatibility. These results suggested the catechol-based adhesive is a very suitable and promising biomaterial in the clinical medicine field.