# Emulsion-Based Encapsulation of Fibrinogen with Calcium Carbonate for Hemorrhage Control

## TL;DR

This study develops self-propelling hemostatic particles using fibrinogen and calcium carbonate to control severe bleeding more effectively.

## Contribution

A novel W/O/W emulsion method is introduced to encapsulate fibrinogen with calcium carbonate, enhancing hemostatic and self-propelling properties.

## Key findings

- Fibrinogen encapsulation increases particle size and hemostatic effects, as shown by gel electrophoresis and ROTEM.
- AC and paraffin produce smaller particles compared to SC and heptane, affecting particle characteristics.
- Combining fibrinogen-CaCO3 particles with TXA+ and thrombin-CaCO3 particles results in synergistic hemostatic effects.

## Abstract

Hemorrhage, particularly non-compressible torso bleeding, remains the leading cause of preventable death in trauma. Self-propelling hemostats composed of thrombin-calcium carbonate (CaCO3) particles and protonated tranexamic acid (TXA+) have been shown to reduce blood loss and mortality in severe bleeding animal models. To further enhance both hemostatic and self-propelling properties, this study was to investigate fibrinogen-CaCO3 particles prepared via a water-oil-water (W/O/W) emulsion method. The particles were characterized using light and fluorescence microscopy, gel electrophoresis, rotational thromboelastometry (ROTEM), and video motion tracking. The method produced spherical micrometer-sized particles with various yields and fibrinogen content, depending on the preparation conditions. The highest yield was achieved with sodium carbonate (SC), followed by ammonium carbonate (AC) and sodium bicarbonate (SBC). AC and paraffin generated smaller particles compared to SC and heptane, which were used as the carbonate source and oil phase, respectively. Fibrinogen incorporation led to an increase in particle size, indicating a correlation between fibrinogen content and particle size. Fluorescence microscopy confirmed successful fibrinogen encapsulation, with various amounts and hemostatic effects as assessed by gel electrophoresis and ROTEM. Combining fibrinogen-CaCO3 particles with TXA+ and thrombin-CaCO3 particles showed synergistic hemostatic effects. All fibrinogen-encapsulated particles exhibited self-propulsion when mixed with TXA+ and exposed to water, regardless of fibrinogen content. This study advances current hemostatic particle technology by demonstrating enhanced self-propulsion and fibrinogen incorporation via the W/O/W emulsion method. Further optimization of the encapsulation method could enhance the effectiveness of fibrinogen-CaCO3 particles for hemorrhage control.