A High Strength Instant Adhesive Nano-hybrid Hydrogel as First-aid Bandage

In this work, a very simple method for preparing a mechanically strong, highly adhesive, and biocompatible hydrogel was reported. The aqueous solution of N-acryloyl-2-aminoacetic acid (ACG) and nano-bioactive glass (BG) was mixed, followed by UV light irradiation to initiate polymerization for preparing the PACG-BG nano-hybrid hydrogels rapidly. The intermolecular hydrogen bonds from PACG chains, coordination between PACG-end carboxyls and metal ions of BG, as well as PACG-BG physical interaction collectively formed multiple physical crosslinks, were contributed to the increased mechanical strengths. The studies of PACG-BG hydrogels demonstrated that tunable mechanical properties, adhesion abilities, and room temperature self-healing ability could be adjusted by changing the contents of ACG and BG. The adhesion strengths of the hydrogels were tested by tension loading in lap-shear mode. The results indicated that at 25 wt% ACG and 6 wt% BG (relative to ACG), the hydrogels could achieve a balance between surface adhesion and cohesion energies; in this case, the maximum instant adhesion strengths toward pig's skin, ion sheet, and ceramic were measured to be 120, 142, and 125 kPa, respectively, and the adhesion strengths of hydrogels toward pig skin, ion sheet, and ceramics was presumably originated from the enrichment of PACG chains to the substrates facilitated by the BG nanoparticles. This allowed more carboxyl groups on the hydrogel surface to form hydrogen bonds, ionic coordination, and dipole interactions with the adherends, consequently leading to the enhanced adhesion to these materials. Intriguingly, the highest tensile strength of the hydrogel was as high as 0.9 MPa, fracture energy could reach 1500 J m(-2), and self-healing efficiency could reach 100% after 12 h at room temperature without manual intervention. The outcomes of in vivo implantation showed that the hydrogel possessed better biocompatibility. In light of its robust adhesion to biological soft tissues, the hydrogel was used for in vitro adhering and mending the animal's gastric perforation. The results revealed that the hydrogel could adhere firmly to the perforated stomach, thus preventing leakage of gastric fluid. This novel organic-inorganic hybrid hydrogel holds promising potential as a biomedical first-aid bandage.