Injectable Self-Healable Nanocomposite Hydrogels with Mussel-Inspired Adhesive Properties for 3D Printing Ink

Injectable self-healable nanocomposite (NC) hydrogels with good mechanical strength and mussel-inspired adhesive property were described in this study. Such NC hydrogels were constructed with a simple solution-mixing of poly(N,N-dimethylacrylmide-stat-3-acrylamidophenylboronic acid) (PDMA-stat-PAPBA), poly(glycerol monomethacrylate) (PGMA), and poly(dopamine) coated chemically reduced grapheme oxide (rGO@PDA) in alkaline surrounding. The formed NC hydrogel networks were dominated by boronic ester dynamic covalent bonds (DCBs), and rGO nanosheets were homogeneously dispersed in the hydrogel matrix, acting as both 2D cross-linkers and reinforcing fillers. The mechanical properties of resultant NC hydrogels were investigated by the rheology and tensile stress–strain tests. The results indicated that the mechanical properties of hydrogels were significantly improved after the incorporation of rGO@PDA. The loading level of rGO@PDA has remarkable effect on the mechanical properties of NC hydrogels. Boronic ester DCBs cross-linking networks conferred the resultant NC hydrogel perfect self-healable and injectable capabilities as well as pH/glucose dual responsive sol-gel reansitions, while free catechol groups in gel matrix gifted NC hydrogels mussel-inspired adhesive property. Such NC hydrogel materials have promising impacts in the fields of 3D printing and tissue engineering.