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In this work, nickel oxide (NiO) nanosheet/nanoball-fower-like structures (NSBS) were directly grown on a NiO seed-coated glass substrate using a low-temperature immersion method at 75 ºC. The thickness, or density, of the nanoball-fower-like structures difered based on the following samples order: NSBS1< NSBS2< NSBS3. The synthesised NSBS flms were investigated in terms of structural, optical, electrical, and humidity sensing characteristics. The X-ray difraction (XRD) analysis revealed that the NSBS samples corresponded to the face-centred cubic NiO with fve difraction patterns indexed to the (111), (200), (220), (311), and (222) planes. The interplanar spacing, lattice parameter, unit cell volume, strain, and stress were also determined from the XRD results. The transmittance spectra showed that the NSBS samples had a transparency of more than 30% in the visible region. The optical bandgap values for the NSBS samples were estimated in the range between 3.72 and 3.75 eV, which is directly related to their lattice expansion and defect characteristics. The current-voltage and Hall efect measurement results revealed that the NSBS2 displayed good electrical properties with the resistance, hole concentration, and hole mobility values of 7.84 MΩ, 8.71×1015 hole/cm−3, and 1.88×102 cm2 /V s, respectively. The NSBS samples performed well for humidity sensing with the highest sensitivity value of 169 being obtained for the NSBS2. These humidity sensing results correlated well with their structural, optical, and electrical characteristics.

We describe a new scaffold-free three-dimensional (3D) cell culture model using cholesteryl ester based lyotropic liquid crystal (LC) substrates. Keratinocytes were deposited randomly on the LC surface where they self-assembled into 3D microtissues or keratinospheroids. The cell density required to form spheroids was optimized. We investigated cell viability using dead/live cell assays. The adhesion characteristics of cells within the microtissues were determined using histological sectioning and immunofluorescence staining. Fourier transform infrared spectroscopy (FTIR) was used to characterize the biochemistry of the keratinospheroids. We found that both cells and microtissues could migrate on the LC surface. The viability study indicated approximately 80% viability of cells in the microtissues up to 20 days of culture. Strong intercellular adhesion was observed in the stratification of the multi-layered microspheroids using field emission-scanning electron microscopy (FE-SEM) and histochemical staining. The cytoskeleton and vinculins of the cells in the microtissues were expressed diffusely, but the microtissues were enriched with lipids and nucleic acids, which indicates close resemblance to the conditions in vivo. The basic 3D culture model based on LC may be used for cell and microtissue migration studies in response to cytochemical treatment.