An Injectable Hybrid Gelatin Methacryloyl/Polydopamine Nanoparticle Bioink for Rapid Hemostasis Applications

Uncontrolled hemorrhage is frequently associated with high mortality. To address this challenge, engineered hydrogels have been widely investigated for hemorrhage control because of their fluid absorption and ability to promote blood coagulation. In this study, we developed injectable bioinks by combining gelatin methacryloyl (GelMA) with polydopamine (PDA) nanoparticles of various sizes. PDA nanoparticles provided abundant surface catechol groups and negative charges. We showed that GelMA hydrogels containing PDA nanoparticles smaller than 600 nm exhibited uniform porous networks. These hydrogels possessed >60% porosity and more than a 6-fold higher swelling capacity than pure GelMA hydrogels. These properties reduced blood clotting time by 2.6-fold, facilitated rapid blood absorption, and promoted fibrin network formation. In addition, the incorporation of PDA nanoparticles also increased the viscosity of the bioinks by about 3-fold when particle sizes were below 600 nm, which enhanced injectability. A dynamic <i>in vitro</i> porcine skin bleeding model showed that GelMA/PDA bioinks cross-linked with hand-held ultraviolet (UV) devices could be integrated into a portable hemostatic kit and stopped bleeding within 120 s. Furthermore, in vivo mice tail amputation and liver injury models demonstrated that hybrid GelMA/PDA hydrogels reduced clotting time by 61% and blood loss by ∼60%. These results were comparable to those of the commercial Celox hemostatic powder. In conclusion, GelMA/PDA bioinks have strong potential as injectable and cytocompatible materials for rapid hemostatic applications.