Synthesis of Polymer-DOTA Conjugates

All Chemicals and reagents were purchased from Aldrich Chemical Co. and used as received, unless otherwise noted. Tert-butyl acrylate was passed through a neutral alumina column to remove the inhibitor before use. 2,2'-Azobis(isobutyronitrile) (AIBN) was recrystallized twice from methanol before use. Lactide was recrystallized twice from hexanes/ethyl acetate before use. Dichloromethane (CH₂Cl₂) was distilled over CaH₂ and stored under N₂ before use. The lactate colorimetric assay kit (ab65331) was purchased from Abcam®. 2-Aminoethyl-mono-amide-DOTA-tris(t-Bu ester) was purchased from Macrocyclics, Inc. Monoamine-functionalized, methoxy-terminated poly(ethylene glycol)s were purchased from Rapp Polymere The. Spectra/Por dialysis membrane tubes were purchased from Spectrum Medical Industries Inc. Nanopure water (18 MΩ·cm) was acquired by means of a Milli-Q water filtration system, Millipore Corp. (Bedford, MA).