A pH, glucose, and dopamine triple-responsive, self-healable adhesive hydrogel formed by phenylborate–catechol complexation†
An injectable polyethylene glycol (PEG) hydrogel was successfully prepared via borate–catechol complexation using dopamine functionalized 4-armed PEG (4-arm-PEG-DA) and phenylboronic acid modified 4-armed PEG (4-arm-PEG-PBA). The hydrogel was formed within 10 s by mixing 15 wt% 4-arm-PEG-DA with 15 wt% 4-arm-PEG-PBA buffer solutions at pH 9.0. The hydrogel was characterized by Fourier transform infrared (FT-IR) spectroscopy, rheological measurements, scanning electron microscopy (SEM) and lap shear strength tests. Furthermore, pH, glucose and dopamine responsiveness of the hydrogel based on phenylborate–catechol complexation was demonstrated by degradation experiments and drug release tests. The lap shear strength tests indicated that the hydrogel possessed the ability of self-healing which was bestowed by the phenylborate–catechol dynamic covalent bond. Moreover, the hydrogel could serve as a decent bio-adhesive due to its adhesion properties on different substrates especially the porcine skin. In vitro cytotoxicity tests demonstrated the excellent cytocompatibility of the hydrogel. The results of all the experiments indicate that our newly developed multi-functionalized hydrogel can have potential applications in biomedical fields such as drug delivery, tissue engineering, and bio-adhesives.