The present disclosure generally relates to compositions comprising fibrin and to methods of forming such compositions. In an embodiment, a method of forming fibrin particles is provided. The method includes introducing a buffer, a fibrinogen solution, and a thrombin solution to a first end of a microfluidic device to form a mixture, the buffer comprising one or more amino acids. The method further includes contacting the mixture with a fluorocarbon oil and a surfactant to form fibrinogen-containing particles, and applying positive pressure to the microfluidic device to cause the fibrinogen-containing particles to flow towards a second end of the microfluidic device. The method further includes collecting the fibrinogen-containing particles at the second end of the microfluidic device; and polymerizing the fibrinogen-containing particles to form fibrin particles.