Flexibility Analysis of DNA Nanotubes with Prescribed Circumferences and Their Pearl-Necklace Assemblies with Gold Nanoclusters

DNA has been demonstrated as a powerful platform for the construction of inorganic nanoparticles (NPs) into complex three-dimensional assemblies. Despite extensive research, the physical fundamental details of DNA nanostructures and their assemblies with NPs remain obscure. Here, we report the identification and quantification of the assembly details of programmable DNA nanotubes with monodisperse circumferences of a 4, 5, 6, 7, 8, or 10 DNA helix and their pearl-necklace-like assemblies with ultrasmall gold nanoparticles, Au25 nanoclusters (AuNCs), liganded by −S­(CH2) n NH3 + (n = 3, 6, 11). The flexibilities of DNA nanotubes, analyzed via statistical polymer physics analysis through atomic force microscopy (AFM), demonstrate that ∼2.8 power exponentially increased with the DNA helix number. Moreover, the short-length liganded AuS­(CH2)3NH3 + NCs were observed to be able to form pearl-necklace-like DNA–AuNC assemblies stiffened than neat DNA nanotubes, while long-length liganded AuS­(CH2)6NH3 + and AuS­(CH2)11NH3 + NCs could fragment DNA nanotubular structures, indicating that DNA–AuNC assembling can be precisely manipulated by customizing the hydrophobic domains of the AuNC nanointerfaces. We prove the advantages of polymer science concepts in unraveling useful intrinsic information on physical fundamental details of DNA–AuNC assembling, which facilitates DNA–metal nanocomposite construction.