Development of albumin macroinitiator for polymers to use in DNA origami coating

Abstract

Background/aim: DNA nanostructures have many advantages over polymers and lipid based drug delivery agents such as biodegradability and biocompatibility. However their transfection rates and stability still limit their widely use in nanomedicine. In this study highly versatile and straightforward albumin coating preparation method is showed for DNA nanostructures. Materials and methods: N-methylolmaleimide was esterified with a-bromoisobutyrl bromide (BiBB) to achive bromine functional structure. Then it was attached to bovine serum albumin (BSA) via cysteine-maleimide bond further to use as macroinitiator for atom transfer radical polymerization (ATRP). Cationic polymers can be synthesized from this end further to use as binding domain for fabricated 60 Helix bundle DNA origami. Results: Proton nuclear magnetic resonance (1 H NMR) analysis used for characterization. Methyelene group hydrogens' peak in 5.0 ppm and strong peak in 1.5-2.0 ppm range showed proper methylolation of maleimide and bromine functional formation, respectively. Then BSA-macroinitiator formation is verified by 1780 Da peak shift in MALDI-TOF (Matrix-assisted laser desorption/ionizationtime of flight) spectrum. Moreover electrophoretic mobility shift assay (EMSA) showed successful dense 60 Helix bundle formation. Conclusion: In this study, a facile method is developed to synthesize protein conjugated-ATRP initiator further can be used in polymerization and coating DNA nanostructures. It is feasible for any protein containing cysteine amino acid.