Reactive multi-arm polymers having branched end groups

The multi-arm polymer of claim 12, wherein the radiocontrast groups comprise a monocyclic or multicyclic aromatic structure that comprises a plurality of radiopaque functional groups and a plurality of hydrophilic functional groups, or wherein the radioactive groups comprise a monocyclic or multicyclic aromatic structure that comprises a plurality of radionuclide groups and a plurality of hydrophilic functional groups.

The multi-arm polymer of claim 13, (a) wherein the radiopaque functional groups or the radionuclide groups are iodide groups and/or (b) wherein the plurality of hydrophilic functional groups are selected from one or more of C1-C4-hydroxyalkyl groups, C1-C4-aminoalkyl groups or C1-C4-carboxyalkyl groups.

A system comprising (a) a first composition comprising a multi-arm polymer comprising a plurality of polymer arms, wherein a first portion of the polymer arms comprise a reactive end group and wherein a second portion of the polymer arms comprise a branched end group that comprise a plurality of covalently attached diagnostic and/or therapeutic groups and (b) a second composition comprising a multifunctional compound that comprises reactive functional groups that are reactive with the reactive end group.

A crosslinked reaction product of (a) a multi-arm polymer comprising a plurality of polymer arms, wherein a first portion of the polymer arms comprise a reactive end group and wherein a second portion of the polymer arms comprise a branched end group that comprise a plurality of covalently attached diagnostic and/or therapeutic groups and (b) a multifunctional compound that comprises functional groups that are reactive with the reactive end group of the multi-arm polymer.