Injectable biopolymer compositions and associated systems and methods

A biopolymer composition for treating an aneurysm, the biopolymer composition comprising:

• an injectable hydrogel comprising:
• at least 2% w/v chitosan, wherein the chitosan has a weight average molecular weight of at least 100 kDa;
• a chemical crosslinker comprising genipin, wherein the genipin forms covalent bonds with the chitosan;
• and
• at least 1% w/v hydroxyethyl cellulose, wherein the hydroxyethyl cellulose interacts noncovalently with the chitosan to inhibit ex vivo phase separation of the chitosan, wherein the hydroxyethyl cellulose has a weight average molecular weight of at least 500 kDa, wherein the hydroxyethyl cellulose comprises a viscosity of at least 2000 Pa-s when measured as a 1% w/v solution at 20° C. and a shear rate of 1/s, and wherein the hydroxyethyl cellulose does not form covalent bonds with the genipin,
• wherein the injectable hydrogel comprises an ex vivo storage modulus that is greater than an ex vivo loss modulus of the injectable hydrogel over a linear viscoelastic region of the injectable hydrogel, and
• wherein the injectable hydrogel is configured to be delivered into the aneurysm without undergoing a phase transition.