Surfactant-dictated syntheses of nanomaterials with well-defined shapes offer an extra dimension of control beyond nanoparticle size and chemical composition on the properties and selfassembly behaviors of colloidal materials. However, the surfactant bilayers on nanocrystals often cause great difficulty toward DNA grafting due to their unfavorable electrostatic charges and dense surface packing. Herein a revisit to this dilemma unveils a rapid charge inversion and enhanced colloidal/chemical stabilities of cationicbilayer-covered nanocrystals upon DNA adsorption. Decoupling this hidden scenario provides a rationale to significantly improve DNA functionalization of surfactant-capped nanocrystals. Accordingly, fully tunable DNA conjugation (via Au−S bonding) on up to seven classes of surfactant-coated metal nanounits is easily and consistently achievable. The DNA−nanocrystal complexes featuring a continuously variable DNA density function well in DNA-guided nanoassembly. Our method opens the door to a wealth of material building blocks derived by surfactant-directed nanosyntheses toward DNA-programmable, extremely diversified, and highly complicated structures and functions.

Self‐assembly of nanomaterials, directed by molecular or supramolecular interactions, is a powerful strategy to build nanoscale devices. Despite many advantages of such solution‐based processes, a big challenge is to realize interparticle ohmic contacts toward facilitated charge transport over a long distance. We report a new concept of primed nanowelding to thread solution‐borne nanoparticles in prescribed assemblies. The process starts with a gap‐specific deposition of Ag2E (E=S, Se) materials in pre‐assembled gold structures, which spontaneously transform into AgAuE semiconductors via directional gold diffusion. Treatment with tributylphosphine generates alloyed Au/Ag welding spots that conductively wire‐up nanoparticles into discrete “molecules” and micron‐long “polymers”. This method is compatible with DNA programming and delivers a possible way to solve the problem of the carrier‐transport dilemma in solution‐processed nanostructures for better‐functioning nanodevices.

Self-assembly of nanomaterials, directed by molecular or supramolecular interactions, is a powerful strategy to build nanoscale devices. Despite many advantages of such solution-based processes, a big challenge is to realize interparticle ohmic contacts toward facilitated charge transport over a long distance. We report a new concept of primed nanowelding to thread solution-borne nanoparticles in prescribed assemblies. The process starts with a gap-specific deposition of Ag 2 E (E = S, Se) materials in pre-assembled gold structures, which spontaneously transform into AgAuE semiconductors via directional gold diffusion. Treatment with tributylphosphine generates alloyed Au/Ag welding spots that conductively wire-up nanoparticles into discrete "molecules" and micron-long "polymers". This method is compatible with DNA programming and delivers a possible way to solve the problem of the carrier-transport dilemma in solution-processed nanostructures for better-functioning nanodevices.