Patent ID: 8003089

Claim:
A Y-shaped branched hydrophilic polymer derivative as set forth by formula I: wherein P a and P b are hydrophilic polymers, which are the same or different; j is an integer from 1 to 12; R i is selected from the group consisting of H, a C 1-12 substituted or unsubstituted alkyl, a substituted aryl, an aralkyl, and a heteroalkyl; X 1 and X 2 independently are linking groups, wherein X 1 is (CH 2 ) n , and X 2 is (CH 2 ) n CO, wherein n is an integer of from 1-10; and F is a functional group capable of reacting with an amino group, a hydroxyl group, or a thiol group of a therapeutic agent or a substrate to form a covalent linkage, selected from the group consisting of a hydroxyl group, a carboxyl group, an ester group, carboxylic acid chloride, hydrazide, maleimide and pyridine disulfide.