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

## TL;DR

This paper introduces a new injectable bioink that can quickly stop bleeding by combining gelatin and polydopamine nanoparticles.

## Contribution

The novel contribution is the development of a hybrid GelMA/PDA bioink with enhanced hemostatic properties and injectability.

## Key findings

- GelMA/PDA hydrogels with PDA nanoparticles under 600 nm showed 60% porosity and 6-fold higher swelling than pure GelMA.
- The bioink reduced clotting time by 61% and blood loss by 60% in animal models, comparable to commercial hemostatic powder.
- The material can be cross-linked with UV light and used in a portable hemostatic kit to stop bleeding within 120 seconds.

## Abstract

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 in vitro 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.