Stimuli-Responsive DNA-Linked Nanoparticle Arrays as Programmable Surfaces.

Self- and directed-assembly approaches have enabled precise control over the composition and geometry of 2D and 3D nanoparticle constructs. However, the resulting structures are typically static, providing only a single structural arrangement of the nanoparticle building blocks. In this work, the power of DNA-linked nanoparticle assembly is coupled to a grayscale patterning technique to create programmable surfaces for assembly and thermally activated reorganization of gold nanoparticle arrays. Direct grayscale patterning of DNA monolayers by electron-beam lithography (DNA-EBL) enables the production of surfaces with nanometer-scale control over the density of functional DNA. This enables tuning of the particle-surface interactions with single-nanoparticle resolution and without the need for a physical template as employed in most directed assembly methods. This technique is applied on suspended membrane structures to achieve high-resolution assembly of 2D nanoparticle arrays with highly mutable architectures. Gold nanorods assembled on grayscale-patterned surfaces exhibit temperature-dependent configurations and ordering behavior that result in tunable polarization-dependent optical properties. In addition, spherical gold particles assembled from a bimodal suspension produce arrays with temperature-dependent configurations of small and large particles. These results have important implications for the design and fabrication of reconfigurable nanoparticle arrays for application as structurally tunable optical metasurfaces.