Systems, kits, and methods for forming in situ silk fibroin fibers and/or aerosols

A spray device for making in situ silk fibroin aerosols and/or fibers, the spray device comprising a first reservoir, a second reservoir, a fluid pathway including a rapid shear mixing chamber and a rapid expansion chamber, and a pump,

• wherein the first reservoir contains a silk fibroin solution and the second reservoir contains a beta sheet initiation solution,
• wherein the silk fibroin solution contains fragments having a molecular weight distribution,
• wherein the beta sheet initiation solution comprises a hygroscopic polymer having a molecular weight of between 7.5 kDa and 15.0 kDa,
• wherein the pump is operatively coupled to the first reservoir, the second reservoir, the rapid shear mixing chamber, and the rapid expansion chamber, such that when the pump is activated, the spray device does the following:
• rapidly mixes the silk fibroin solution and the beta sheet initiation solution under shear force to provide a mixed solution having rapidly initiated formation of beta sheet crystal structure;
• and
• rapidly expands the mixed solution, thereby providing elongation force to the mixed solution and making the silk fibroin aerosols and/or fibers,
• wherein the pump rapidly mixes and rapidly expands within 1 second of one another,
• wherein the spray device makes the silk fibroin aerosols when the molecular weight distribution is below an aerosol-fiber threshold,
• wherein the spray device makes the silk fibroin fibers when the molecular weight distribution is above the aerosol-fiber threshold.