Nanotextured silicon substrata with parallel ridges separated by grooves with equal width from 90 to 500 nm, were fabricated by electron beam lithography and dry etching techniques. Osteoblast-like cells, MG-63, were cultured on the sterilized nanopatterned substrata for 4 or 24 h, and then imaged by scanning electron microscopy. The influence of substrate topography on cell morphology was analyzed by image software. We found the initially cells spread faster on the nanopatterned surfaces than on the flat surface, suggesting that surface anisotropic feature facilitates initial cell extension along its direction. However, because of inhibition of cell lateral expansion across nanogrooved surfaces, the cells on the nanogrooved surface did not further expand laterally, and cell spreading area was less than that on the flat surface after 24 h of incubation. Cells elongated and aligned along the direction of grooves on all the nanopatterned substrata. Furthermore, fluorescence staining of cell nuclei indicated that the nuclei of the cells cultured on the nanopatterned surfaces also displayed a more elongated and aligned morphology along the direction of the grooves. Since cell shape and orientation influence cell functions and alignment of extracellular matrix secreted by cells, our results may provide the information regarding responses of osteoblasts to the nanostructure of collagen fibrils, and benefit bone tissue engineering and surface design of orthopedic implants.

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In this letter, the authors propose a practical and reliable approach—using deposited multiwalled carbon nanotubes (MWCNTs) as source and drain electrodes—for reducing the contact resistance (Rc) in pentacene-based bottom-contact thin-film transistors. The value of Rc of the devices was closely linked to the resultant length of the deposited MWCNTs; the lowest value was 3×108Ωμm. The largest saturation mobility was 0.14cm2∕Vs; this value reached up to three times higher when the threshold voltage was determined using the maximum transconductance (Gm,max) extrapolation method, rather than the constant current method. The on/off ratio was more than 106.