Morphology Control of Ni(II)-NTA-End-Functionalized Block Copolymer and Bio-Conjugation through Metal-Ligand Complex

This study demonstrates the synthesis of an amphiphilic block copolymer, Ni²⁺-nitrilotiracetic acid-end-functionalized-poly(poly(ethylene glycol)methyl ether methacrylate)-block-polystyrene (NTA-p(PEGMA-b-St)), morphology control via their self-assembly behavior and reversible bioconjugation of hexahistidine-tagged green fluorescent protein (His₆-GFP) onto the surfaces of polymeric vesicles through nitrilotriacetic acid (NTA)-Ni²⁺-His interaction. First, the t-boc-protected-NTA-p(PEGMA-b-St) was synthesized by atom transfer radical polymerization. After the removal of the t-boc protecting group, the NTA group of the polymer was complexed with Ni²⁺. To induce self-assembly, water was added as a selective solvent to the solution of the copolymer in tetrahydrofuran (THF). Varying the water content of the solution resulted in various morphologies including spheres, lamellas and vesicles. Finally, polymeric vesicles decorated with green fluorescent protein (GFP) on their surfaces were prepared by the addition of His₆-GFP into the vesicles solution. Reversibility of the binding between vesicles and His₆-GFP was confirmed with a fluorescent microscope.