Polymer-protein conjugation via a ‘grafting to’ approach – a comparative study of the performance of protein-reactive RAFT chain transfer agents

• Published in: Polymer chemistry Vol. 6; no. 31; pp. 5602 - 5614
• Main Authors: Vanparijs, N., Maji, S., Louage, B., Voorhaar, L., Laplace, D., Zhang, Q., Shi, Y., Hennink, W. E., Hoogenboom, R., De Geest, B. G.
• Format: Journal Article
• Language: English
• Published: 01.01.2015
• Subjects: Addition polymerization; Chain transfer; Conjugation; Formulations; Proteins; Rafts; Reagents; Residues
• ISSN: 1759-9954; 1759-9962
• DOI: 10.1039/C4PY01224K

Efficient polymer-protein conjugation is a crucial step in the design of many therapeutic protein formulations including nanoscopic vaccine formulations, antibody-drug conjugates and to enhance the in vivo behaviour of proteins. Here we aimed at preparing well-defined polymers for conjugation to proteins by reversible addition–fragmentation chain transfer (RAFT) polymerization of both acrylates and methacrylamides with protein-reactive chain transfer agents (CTAs). These RAFT agents contain either a N -hydroxysuccinimide (NHS) or pentafluorophenyl (PFP) ester moiety that can be conjugated to lysine residues, and alternatively a maleimide (MAL) or pyridyl disulfide (PDS) moiety that can be conjugated to cysteine residues. Efficiency of the bioconjugation of these polymers to bovine and avian serum albumin was investigated as a function of stoichiometry, polymer molecular weight and the presence of reducing agents. A large molar excess of polymer was required to obtain an acceptable degree of protein conjugation. However, protein modification with N -succinimidyl- S -acetylthiopropionate (SATP) to introduce sulfhydryl groups onto primary amines, significantly increased conjugation efficiency with MAL- and PDS-containing polymers.