Exploitation of orientation of liquid crystals 5CB and DSCG near surfaces to detect low protein concentration

Kumar, Anil; Pattanayek, Sudip K.

doi:10.1080/02678292.2015.1044576

Cited by 10 publications

(6 citation statements)

References 30 publications

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“…As BSA accumulated at the LC-glass interface, light leakage increased with increasing concentrations of BSA (Figure 4). A similar darkto-bright transition was also reported in the detection of BSA by homeotropically aligned DSCG [34]. However, DSCG tends to reorient from the homeotropic to the planar state over time [35].…”

Section: Lclc-based Spectrometric Quantitation Of Bsasupporting

confidence: 77%

Label-Free Detection and Spectrometrically Quantitative Analysis of the Cancer Biomarker CA125 Based on Lyotropic Chromonic Liquid Crystal

Shaban

Lee

2021

Biosensors

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Compared with thermotropic liquid crystals (LCs), the biosensing potential of lyotropic chromonic liquid crystals (LCLCs), which are more biocompatible because of their hydrophilic nature, has scarcely been investigated. In this study, the nematic phase, a mesophase shared by both thermotropic LCs and LCLCs, of disodium cromoglycate (DSCG) was employed as the sensing mesogen in the LCLC-based biosensor. The biosensing platform was constructed so that the LCLC was homogeneously aligned by the planar anchoring strength of polyimide, but was disrupted in the presence of proteins such as bovine serum albumin (BSA) or the cancer biomarker CA125 captured by the anti-CA125 antibody, with the level of disturbance (and the optical signal thus produced) predominated by the amount of the analyte. The concentration- and wavelength-dependent optical response was analyzed by transmission spectrometry in the visible light spectrum with parallel or crossed polarizers. The concentration of CA125 can be quantified with spectrometrically derived parameters in a linear calibration curve. The limit of detection for both BSA and CA125 of the LCLC-based biosensor was superior or comparable to that of thermotropic LC-based biosensing techniques. Our results provide, to the best of our knowledge, the first evidence that LCLCs can be applied in spectrometrically quantitative biosensing.

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Section: Lclc-based Spectrometric Quantitation Of Bsasupporting

confidence: 77%

Label-Free Detection and Spectrometrically Quantitative Analysis of the Cancer Biomarker CA125 Based on Lyotropic Chromonic Liquid Crystal

Shaban

Lee

2021

Biosensors

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“…Typically speaking, the initial alignments of the LC molecules are related to the orientation force provided by the alignment layer at the phase interface. At the LC-solid interface, the alignment layers such as siloxane, aliphatic chain, and oligonucleotides favor the perpendicular alignment of the molecules, [88,89] while the parallel ravine prepared by etching techniques and polyimide (PI) treated by directed rubbing can lead to parallel alignment. [90,91] In addition, at the LC-aqueous interface, the LC alignment can be tuned by varying the components of the aqueous phase.…”

Section: Alignmentsmentioning

confidence: 99%

Design and Applications of Liquid Crystal Biophotonic Sensors for Ion Detection

2022

Advanced Photonics Research

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Liquid crystals (LCs) are nanophotonic materials which can interact with light in the molecular scale. While the LCs are widely used in various displays, last decade has witnessed emerging applications of the LCs for nondisplays. Based on the unique stimuli–responsive property and optical property, the applications of the LCs in the field of sensors are widely explored. In addition, ions are widely distributed in nature and bionts, playing critical roles in many physiological activities and ecological cycles. Appropriate amount of ions is beneficial to the human body, while the excess ions can cause irreversible damages. As a result, a variety of LC sensors are proposed to detect the ion concentration in both body fluids and water samples. This article reviews the design principles, applications, and existing problems of the LC ion sensors. The geometries, alignments, and optical signals of the sensors, which can guide the design of the devices, are first discussed. Afterward, two types of LC ion sensors aiming at detecting metal ions and nonmetallic ions, respectively, are illustrated. Finally, the current challenges and potential development directions of the LC ion sensors are introduced briefly.

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“…The homeotropic arrangement was that the long axis of 5CB was parallel to the direction of the surface normal, which can be induced by a lecithin layer of hydrophobic surfactant monolayer [13]. Kumar et al [6] found that 5CB aligned homeotropically on both the aminopropyl tri-ethoxy silane (APTES) and dimethyloctadecyl [3-(trimethoxysilyl) propyl] ammonium chloride (DMOAP) surfaces. Fourier transform infrared spectroscopy has confirmed that the C≡N of 5CB interacted with N of APTES and N + of DMOAP [6,17,56].…”

Section: Effect Of Polarity On Molecular Distributionmentioning

confidence: 99%

“…Kumar et al [6] found that 5CB aligned homeotropically on both the aminopropyl tri-ethoxy silane (APTES) and dimethyloctadecyl [3-(trimethoxysilyl) propyl] ammonium chloride (DMOAP) surfaces. Fourier transform infrared spectroscopy has confirmed that the C≡N of 5CB interacted with N of APTES and N + of DMOAP [6,17,56]. Yang et al [57] investigated the interfacial orientation of 5CB supported on salts of metal ions.…”

Section: Effect Of Polarity On Molecular Distributionmentioning

confidence: 99%

“…The detection and control of molecular orientation aid in the development of novel technologies such as organic solar cells [2], biosensors [6], superhydrophobic surfaces [7,8] and surface inhibitors [9−11]. The molecular stacking and crystallinity significantly influence the exciton dissociation and free charge transport and result in different power conversion efficiencies [3].…”

Section: Introductionmentioning

confidence: 99%

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Molecular behaviors in thin film lubrication—Part one: Film formation for different polarities of molecules

et al. 2019

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There are three unsolved problems in thin film lubrication (TFL) since it was proposed 20 years ago, i.e., the determination of the type of molecules that can enter the contact region efficiently during sliding, the orientation of molecules in the contact region, and the effect of solid surfaces on the liquid molecular orientation in TFL. In order to answer the first two questions, an in situ measurement system comprising a self-designed Raman microscopy and relative optical interference intensity (ROII) system was set up to study the molecular behaviors. A variety of binary mixtures were used as lubricants in the test, and the concentration distribution profile and orientation of the additive molecules in TFL were characterized. The molecular behavior was determined via a combination of shearing, confinement, and surface adsorption. Furthermore, the difference in molecular polarity resulted in different competing effect of surface adsorption and intermolecular interaction, the influence of which on molecular behavior was discussed. Polar additive molecules interacted with the steel surface and exhibited an enrichment effect in the Hertz contact region when added into a nonpolar base oil. No enrichment effect was observed for nonpolar molecules that were added into the nonpolar base oil and polar molecules added into polar base oil. The enrichment of additive molecules enhanced the film-forming ability of the lubricant and resulted in a reduction in the friction coefficient of up to 61%. The orderly arrangement of the additive molecules was another reason for the friction-reducing. A binary multilayer model was proposed to illuminate the molecular behavior in the TFL, and the model was supported by contrary experiment results in elastohydrodynamic lubrication. This research may aid in understanding the nanoscale lubrication mechanism in TFL and the development of novel liquid lubricants.

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Exploitation of orientation of liquid crystals 5CB and DSCG near surfaces to detect low protein concentration

Cited by 10 publications

References 30 publications

Label-Free Detection and Spectrometrically Quantitative Analysis of the Cancer Biomarker CA125 Based on Lyotropic Chromonic Liquid Crystal

Label-Free Detection and Spectrometrically Quantitative Analysis of the Cancer Biomarker CA125 Based on Lyotropic Chromonic Liquid Crystal

Design and Applications of Liquid Crystal Biophotonic Sensors for Ion Detection

Molecular behaviors in thin film lubrication—Part one: Film formation for different polarities of molecules

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