We report on a simple and efficient method for the selective positioning of Au/DNA hybrid nanocircuits using a sequential combination of electron-beam lithography (EBL), plasma ashing, and a molecular patterning process. The nanostructures produced by the EBL and ashing process could be uniformly formed over a 12.6 in2 substrate with sub-10 nm patterning with good pattern fidelity. In addition, DNA molecules were immobilized on the selectively nanopatterned regions by alternating surface coating procedures of 3-(aminopropyl)triethoxysilane (APS) and diamond like carbon (DLC), followed by deposition of DNA molecules into a well-defined single DNA nanowire. These single DNA nanowires were used not only for fabricating Au/DNA hybrid nanowires by the conjugation of Au nanoparticles with DNA, but also for the formation of Au/DNA hybrid nanocircuits. These nanocircuits prepared from Au/DNA hybrid nanowires demonstrate conductivities of up to 4.3 × 105 S/m in stable electrical performance. This selective and precise positioning method capable of controlling the size of nanostructures may find application in making sub-10 nm DNA wires and metal/DNA hybrid nanocircuits.
An efficient platform capable of cell adhesion needs to be developed to understand cell activities such as cell differentiation, diffusion, and migration. The basic sequence of cell adhesion involves cells communicating with their environment by generating mechanical and chemical signals. Thin polymeric films with micro- or nano-patterns are widely used to support cell growth with conformal contact at the biointerface. However, stable and biocompatible films with high reproducibility on a flexible substrate remain a challenge. As described here, we developed micro-pattern poly(tetrafluoroethyleneco-perfluoro-3,6-dioxa-4-methyl-7-octenesulfonic acid) (Nafion) films fabricated by a molding process. We present the fabrication and characterization of flexible, micro-patterned Nafion films and the evaluation of cell adhesion and alignment on these films. We found that cell adhesion and migration/direction could be modulated by controlling the surface architecture. This approach offers a new platform that constitutes a promising tool for use in flexible cell-based platforms and devices to observe cell-cell and cell-surface interactions.
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