We achieved vertically aligned (VA) liquid crystals (LCs) on aluminum oxide (Al2O3) films deposited via e-beam evaporation using a rubbing treatment. Uniform and vertical LC alignment was achieved and high thermal stability was obtained using these substrates. By analyzing measurements from optical retardations, we confirm that the LC orientation is adjustable using rubbing treatment. The superior electro-optical characteristics of the VA cells based on Al2O3 films are measured and compared with those based on polyimide layers, indicating that this approach will allow the fabrication of high-performance, advanced LC displays using a conventional rubbing process.

ABSTRACT We present the fabrication of an anisotropic structure on a polyurethane (PU) film for aligning liquid crystal (LC) molecules with ion beam (IB) irradiation at an incident angle. The obtained anisotropic structure assembles the LC cells in a layer that aligns LC molecules uniformly. Polarised optical microscopy images of an LC cell fabricated with IB-irradiated PU were captured to confirm the LC alignment state and compared with those fabricated with non-treated PU. To analyse the effects of the IB irradiation, X-ray photoelectron spectroscopy and field-emission scanning electron microscopy were used to investigate the chemical and morphological modifications, respectively. IB irradiation modifies the chemical structure of PU, which indicates that a new skin layer is formed on the PU films. This skin layer generates an in-plane compressive strain, thereby creating buckles on the PU films. Simultaneously, the physical collision of the reactive Ar+ ions during IB irradiation induces a directional strain on the surface, thereby forming a unidirectional structure of buckles along the direction of IB irradiation. The PU film annealed at 200°C showed the high average transmittance of 88.9%, which is appropriate as an alignment layer. Graphical Abstract

We report uniform and homogeneous liquid crystal (LC) alignment using ion beam (IB)-irradiated poly(styrene-maleic anhydride) (SMA) films as an alignment layer when the IB incidence angle is controlled. The molecular polarity on the SMA surface increased with IB irradiation, especially at an incidence angle of 30 degrees, resulting in strong van der Waals forces between the LC molecules and the surface. Atomic force microscopy and X-ray photoelectron spectroscopy were used to determine the LC alignment mechanism. Chemical structure analysis indicated that the orientation of LC molecules was due to van der Waals forces and selective breaking of C-C bonds by IB irradiation. The potential application of SMA substrates as alignment layers for display devices was further supported by their higher thermal stability (220 degrees C) compared with that of conventional rubbed SMA (160 degrees C) and rubbed polyimide (160 degrees C). Therefore, LC cells with IB-irradiated SMA are potential candidates for alternative alignment layers in LC applications. (C) 2017 Elsevier B.V. All rights reserved.

Doping with cerium (IV) oxide (CeO2) nanoparticles can significantly enhance the thermal stability and electro-optical (EO) properties of nematic liquid crystal (NLC) systems. Thermal stability was improved without aggregation and reduction of transmittance by adding CeO2 nanoparticles in a liquid crystal medium. In particular, the EO properties greatly improved in CeO2-dispersed NLC cells. The threshold voltage reduced from 3.027 to 2.279V and the response time decreased from 13.097 to 9.970ms with increased CeO2 nanoparticles in the NLC cells. The improved properties of liquid crystals doped with CeO2 nanoparticles depend on the anchoring energy and the electric field of the CeO2-dispersed liquid crystal displays.[GRAPHICS]

Here we describe a label-free detection strategy for point mutation in breast cancer susceptibility gene BRCA1 utilizing ligation chain reaction (LCR) and zip-code array. We amplified the genomic regions containing mutation sites by polymerase chain reaction (PCR) to prepare the template for LCR. Then we ligated a primary probe extended by zip-code complementary at the 5' end with a 3'-thiol modified secondary probe. The resulting ligated product was labeled with gold nanoparticles and allowed to hybridize with corresponding zip-code sequences on the microarray. Finally, we applied silver enhancement to amplify the signals. Using this strategy, we successfully genotyped BRCA1 mutation, which was detected by naked eye.

A simple, highly efficient immobilization method to fabricate DNA microarrays, that utilizes gold nanoparticles as the mediator, has been developed. The fabrication method begins with electrostatic attachment of amine-modified DNA to gold nanoparticles. The resulting gold-DNA complexes are immobilized on conventional amine or aldehyde functionalized glass slides. By employing gold nanoparticles as the immobilization mediator, implementation of this procedure yields highly homogeneous microarrays that have higher binding capacities than those produced by conventional methods. This outcome is due to the increased three-dimensional immobilization surface provided by the gold nanoparticles as well as the intrinsic effects of gold on emission properties. This novel immobilization strategy gives microarrays that produce more intense hybridization signals for the complementary DNA. Furthermore, the silver enhancement technique, made possible only in the case of immobilized gold nanoparticles on the microarrays, enables simple monitoring of the integrity of the immobilized DNA probe.

We describe here ligation-based strategy to detect mutations in BRCA1 utilizing zip-code microarray technology. In our first approach, PCR was performed to amplify the genomic regions containing the mutation sites. The PCR products were then used as templates in a subsequent ligation reaction using two ligation primers that flanked the mutation site. The primary allele-specific primer is designed to contain a base of mutation site at its 3′ end with 5′ complementarity to the respective zip-code sequence while the secondary common primer is modified by biotin at its 3′ end. Depending on the genotype of samples at the mutation site, the nick between the two ligation primers can be sealed in the presence of DNA ligase. The ligation products were then hybridized on the zip-code microarray followed by staining with streptavidine-cy3 to generate a fluorescent signal. Using this strategy we successfully genotyped selected Korean-specific mutation sites in exon 11 of BRCA1 with a wild type and two heterozygote mutant samples. Furthermore, we also demonstrated that ligase chain reaction using unamplified genomic DNA as direct templates is enough to generate sufficient signals for correct genotypings in a multiplexed manner, verifying first that PCR is not essential for this microarray-based strategy.

In this report, a reliable peptide nucleic acid (PNA) microarray-based method for accurately detecting single nucleotide polymorphism (SNP) in human genes is described. The technique relies on the mismatched cleavage activity of a single-strand specific (SSS) nuclease. PCR amplification was performed to prepare gene fragments containing the mutation sites. The amplified fragments were then employed as templates for the SSS nuclease reaction using chimeric probes, modified with biotin at the 5′ end and extended with a unique anchoring zip-code complement sequence at the 3′ end. The SSS nuclease promotes cleavage of heteroduplex DNAs at base mismatched positions to produce crumbled chimeric probes in the presence of imperfectly matching template strands. In contrast, the probes remain intact when they interact with perfectly matched template strands. Only the non-fragmented probes generate fluorescence signals after treatment with streptavidin-Cy3 on the PNA zip-code array. This methodology was used to successfully genotype selected Korean-specific BRCA mutation sites with wild type and mutant samples. The investigation has led to the development of a reliable SSS nuclease-based system for the diagnosis of human genetic mutations or SNPs.