The basement membrane of the human corneal epithelium comprises topographic features including fibers, pores, and elevations with feature dimensions on the order of 20-400 nm. Understanding the impact of sub-micron and nanotopography on corneal cell behavior will contribute to our understanding of biomechanical cues and will assist in the design of improved synthetic corneal implants. We utilized well defined ridge and groove wave-like nanostructures (wave ordered structures, WOS) of 60-140 pitches (30-70 nm ridge widths) and 200 nm depths to assess human corneal epithelial cell (HCEC) contact guidance and to establish HCEC contact acuity defined as the lower limit in feature dimensions at which cells respond to biomimetic topographic cues. Results using the WOS substrates demonstrate that HCEC contact acuity is in the range of 60 nm pitch for cells in a serum-free basal medium (EpiLife ® ) and in the range of 90 nm pitch for cells in epithelial medium. To further investigate the influence of HCEC contact acuity in the presence of larger topographic cues, we fabricated 70 nm pitch WOS overlaid parallel to the top of the ridges of 800-4000 nm pitch. HCEC cultured in epithelial medium demonstrate a significant increase in the percent of cells aligning to 4000 nm pitch topography with WOS overlay compared to controls (both flat and 70 nm WOS alone) and 4000 nm pitch topography alone. These results highlight the significance of the lower range of basement membrane scale topographic cues on cell response and allow for improved prosthetic design.

A self-forming nanostructure—a wave-ordered structure with a controllable period (20–180 nm)—results from the off-normal bombardment of amorphous silicon layers by low-energy (∼ 1–10 keV) nitrogen ions. The nanostructure has been modified by reactive-ion etching in plasma to form a periodic nanomask on the surface of the channel region of a metal–oxide–semiconductor field-effect transistor (MOSFET). Implantation of arsenic ions through the nanomask followed by the technological steps completing the fabrication of the MOSFET resulted in a periodically doped channel field-effect transistor (PDCFET), which can be considered as a chain of short-channel MOSFETs with a common gate. Having worse subthreshold characteristics, PDCFETs show greater drain current and transconductance than to MOSFETs without a periodically doped channel. This improvement in device performance is attributed to the fact that the channel length is cut by the length of high-conductivity doped areas in the channel and that the voltage is distributed between the areas, depressing the scaling rules for short-channel MOSFETs and allowing the channel to be less doped between the areas, thus keeping drift mobility high.

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A new approach is proposed to the synthesis of a semipolar GaN on a Si(100) substrate at the surface of which the V-shaped nanostructures with the characteristic size of elements as low as 100 nm are formed. It has been demonstrated that application of buffer layers of 3C-SiC and AlN enables formation of the GaN(10-11) layer characterized by the full width at half maximum value as low as ω θ 45 arcmin for the X-ray diffraction rocking curve. The model based on anisotropic nucleation of AlN on the V-shaped nanostructure is proposed to explain the growth of the GaN layer in a single semipolar direction.

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