Fig. 1

Programmable chain-growth copolymerization of DHTs to form 1D nanofilaments. a Schematics of structures (left), sequences (middle), and simplified cartoons of two DHT monomers A (blue) and B (red) and initiator strand I (gray). Each monomer is assembled from four single-stranded DNA. Strand a1 or b1 serves as a rigid core linking two crossover junctions. Strands a2 to a4 and b2 to b4 provide sticky ends for associations with the complementary sequences in the neighboring monomers of the copolymer. Strand a4 or b4 also serves as hairpin domain with a toehold to be activated in strand displacement reactions (SDRs) for chain-growth copolymerization. b Chain-growth supramolecular copolymerization of monomers A and B initiated with I. The copolymerization starts with the SDR of initiator I with monomer A. The exposed loop sequence of activated A invades the hairpin domain of B to activate it with an exposed sequence identical to I, which could further activate another monomer A. The completed chain-growth copolymerization is achieved by alternating activation and propagation of monomers A and B. (Inset) Simplified diagram of chain-growth copolymerization