Controlling the DNA Hybridization Chain Reaction

A novel method for controlling the oligomerization of metastable DNA hairpins using the hybridization chain reaction (HCR) is reported. Control was achieved through the introduction of a base-pair mismatch in the duplex of the hairpins. The mismatch modification allows one to kinetically differentiate initiation versus propagation events, leading to DNA oligomers up to 10 monomers long and improving dispersities from 2.5 to 1.3-1.6. Importantly, even after two consecutive chain extensions, dispersity remained unaffected, showing that well-defined block co-oligomers can be achieved. As a proof-of-concept, this technique was then applied to hairpin monomers functionalized with a mutant green fluorescent protein to prepare protein oligomers. Taken together, this work introduces an effective method for controlling living macromolecular HCR oligomerization in a manner analogous to the controlled polymerization of small molecules.