Pathway to colloidal polymers at the nanoscale from DNA-coated patchy nanoparticles

Building materials through colloidal self-assembly, a powerful bottom-up approach, has recently seen remarkable innovations starting with isotropic colloids like monodisperse spherical particles as building blocks. These particles can efficiently self-assemble into thermodynamically favored structures such as fcc and hcp lattices1. Besides, patchy particles have received significant interest for their ability to exhibit directional and selective interactions, forming building blocks that encode the target materials’ structural information2. Here we report the synthesis of patchy nanoparticles, consisting of a silica core of ~50 nm diameter and two polystyrene patches, obtained using a seeded-growth emulsion polymerization and a subsequent dissolution step. The synthesis takes place using monodisperse silica nanoparticles previously surface-modified allowing a fine control of the number and location of patches with a morphological yield of 97% 3. To reach precise self-assembled structures, we rely on DNA coatings as a tool to program the interactions between particles. An azide terminated block copolymer is anchored at the patches surface through a selective swelling-deswelling process4, later reacted with DBCO-terminated DNA strands to encode the interaction between patches. We conducted a comprehensive analysis of the morphological evolution of the particles using TEM and AFM to compare the particles morphology before and after the patches’ selective coating. We show that the thermo-reversibility and specificity of DNA hybridization between patches leads to the assembly of one-dimensional structures at the nanoscale, called colloidal polymers5. We highlight the modulation of the chain length based on incubation time and the formation of hetero-sequences according to the patches coatings.