Radiopaque hydrolysable hydrogels and methods of treatment using same

A method of forming a reactive multi-arm polymer that comprises (a) reacting a multi-arm polymer that comprises three or more polymer arms linked to a core region, at least three of the polymer arms comprising the hydrophilic polymer segment and an amino end group, with an iodinated lactone in a ring-opening reaction to form at least three polymer arms that comprise a hydroxy-containing iodinated lactone residue that is linked to the hydrophilic polymer segment through a linkage that comprises an amide group;

• (b) reacting the reaction product of step (a) with a cyclic anhydride in a ring opening reaction to form at least three polymer arms that comprise carboxyl end groups that a linked to the iodinated lactone residue through a linkage that comprises an ester group;
• and (c) reacting the reaction product of step (b) with an N-hydroxy cyclic imide compound in an amide coupling reaction to form the reactive multi-arm polymer.

A method of treatment comprising administering to a subject a mixture that comprises (a) a reactive multi-arm polymer that comprises three or more polymer arms linked to a core region, at least three of the three or more polymer arms comprising a cyclic-imidyl ester group, a hydrolysable ester group, an iodinated lactone residue, an amide group and a hydrophilic polymer segment, where the cyclic-imidyl ester group is linked to the iodinated lactone residue through the hydrolysable ester group, the iodinated lactone residue is linked to the hydrophilic polymer segment through the amide group, and the hydrophilic polymer segment is linked to the core region and (b) a polyamino compound comprising at least two amino (—NH2) groups, wherein the mixture is administered under conditions such that the polyamino compound and the reactive multi-arm polymer react to form a crosslinked hydrogel after administration.