Synthesis of doxorubicin-protein conjugates via cobalt coordination chemistry: Conjugates of transferrin and immunoglobulin G
Protein-drug conjugates are a rapidly expanding family of therapeutics that hold significant potential to ameliorate off-target toxic effects commonly observed in patients undergoing chemotherapy. chemotherapy. In this context, the protein acts as a nanoscale delivery vector that alters the biodistribution of the drug upon administration by restricting its unhindered distribution in vivo. This thesis explores the use of cobalt coordination chemistry in the synthesis of doxorubicin-protein conjugates. Previous work has shown that cobalt can be used to crosslink amine-containing molecules in a reversible reaction that only utilizes the lone pair of electrons on nitrogen to form a dative bond with cobalt. Doxorubicin was chosen for initial studies because it contains a primary amine that could be crosslinked with lysine residues on a protein to form a protein-drug conjugate. Conjugates of dox with albumin, transferrin, and immunoglobulin G were investigated to demonstrate the broad applicability of the method for bioconjugation reactions. Drug loading was investigated by HPLC, and the conjugates further characterized by dynamic light scattering, calorimetry, and cytotoxicity. Details of the effects of reaction conditions on synthesis of stable conjugates will be discussed.