Fig. 5
DNA-mediated self-assembly of Janus particles in the presence of depletion force. a–c Optical microscope images for self-assembled structures of DNA-coated Janus particles with various patch ratios between χ = 0.3 and 0.65 in the presence of 1% of F127, which forms micelles and introduces a weak attractive depletion interaction. a When χ = 0.3, particles self-assemble into dimer chains as well as ring structures, which form only when there is a depletion interaction. b For χ = 0.34, the same structures are observed, as well as densely-packed chains which we call compact chains (CC). For χ = 0.41, most chains are compact chains. c However, the structures of trimer chains (χ = 0.48) and d bilayers (χ = 0.6 and 0.65) are unchanged. e Half of the particles of a dimer chain can touch the substrate if the chain is straight (top) or has a constant radius of curvature (middle). However, when the dimer chain curvature is not constant, as for an S-shaped chain (bottom), one or more particles in the chain detach from a flat substrate. f Bright field (top) and fluorescent (middle) optical microscope images of rings consisting of 32–48 particles. Yellow dashed circles in bright field/fluorescent overlay (bottom) show the locations octahedral defects that appear for χ = 0.34. Illustration on the right shows the structure of a single octahedral defect. g Phase diagram of Janus particles obtained by simulation in the presence of a depletion interaction (εdep = 0.1)
