After DBCO-NH2 and DMAP addition, all copolymers were purified using 96-well Zeba filter plates (Thermo Fisher Scientific) manually packed with Sephadex G-25 superfine, following a previously published protocol. Incorporated DBCO concentration was quantified by measuring absorbance at the characteristic wavelength of 310 nm and comparing to a DBCO-NH2 standard curve. Addition of WDCL and EPO peptides to conjugate onto copolymers by strain-promoted azide-alkyne cycloaddition (SPAAC) was performed using the same automated reagent addition scripts as the DBCO-NH2 and DMAP addition step and left overnight for reaction completion.