Polyelectrolyte-coated liquid crystal droplets for detecting charged macromolecules

Bera, Tanmay; Fang, Jiyu

doi:10.1039/c2jm00038e

Cited by 50 publications

(67 citation statements)

References 39 publications

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“…5-7, 14, 17, 28 Because the analytes used in this study induce a bipolar-to-radial ordering transition, we measured scatter plots for 5CB-in-water emulsions containing different percentages of radial LC droplets. The emulsions were prepared by mixing bipolar LC droplets (bare aqueous-LC interfaces) with DPPC-coated radial droplets.…”

Section: Resultsmentioning

confidence: 99%

“…Typically, quantitation has involved analysis of a large number of polarized light micrographs to determine the ordering within hundreds of LC droplets contained in emulsions. 6-7, 14, 17, 28 This process is not well-suited as the basis of an analytical method for three reasons. First, optical imaging and analysis of images of individual LC droplets is laborious (typically, hundreds of LC droplets must be analyzed to obtain statistically robust results).…”

Section: Introductionmentioning

confidence: 99%

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Analysis of the Internal Configurations of Droplets of Liquid Crystal Using Flow Cytometry

et al. 2013

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We report the use of flow cytometry to identify the internal ordering (director configurations) of micrometer-sized droplets of thermotropic liquid crystals (LCs) dispersed in aqueous solutions of adsorbates (surfactants and phospholipids). We reveal that changes in the configurations of the LC droplets induced by the adsorbates generate distinct changes in light scattering plots (side versus forward scattering). Specifically, when compared to bipolar droplets, radial droplets generate a narrower distribution of side scattering intensities (SSC, large angle light scattering) for a given intensity of forward scattering (FSC, small angle light scattering). This difference is shown to arise from the rotational symmetry of a radial LC droplet which is absent for the bipolar configuration of the LC droplet. In addition, the scatter plots for radial droplets possess a characteristic “S-shape”, with two or more SSC intensities observed for each intensity of FSC. The origin of the experimentally observed S-shape is investigated via calculation of form factors and established to be due to size-dependent interference effects that differ for the forward and side scattered light. Finally, by analyzing emulsions comprised of mixtures of bipolar and radial droplets at rates of up to 10,000 droplets per second, we demonstrate that flow cytometry permits precise determination of the percentage of radial droplets within the mixture with a coefficient of determination of 0.98 (as validated by optical microscopy). Overall, the results presented in this paper demonstrate that flow cytometry provides a promising approach for high throughput quantification of the internal configurations of LC emulsion microdroplets. Because large numbers of droplets can be characterized, it enables statistically robust analyses of LC droplets. The methodology also appears promising for quantification of chemical and biological assays based on adsorbate-induced ordering transitions within LC droplets.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Analysis of the Internal Configurations of Droplets of Liquid Crystal Using Flow Cytometry

et al. 2013

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“…Alino et al, 2011;Alino et al, 2012;Bera and Fang, 2012;Bera and Fang, 2013;Gupta et al, 2009; Khan et al, 2011; Kinsinger et al., 2010;Zou et al, 2011). In particular, these offer routes to design simple, economic and convenient passive sensing devices that provide a high spatial resolution of micrometers with a very high sensitivity.…”

Section: A New Pathway For the Formation Of Liquid Crystal Droplets Wmentioning

confidence: 99%

Liquid Crystal Biosensors: New Approaches

Sidiq¹

2016

Proceedings of the Indian National Science Academy

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This review describes recent advances in the area of research involving the interfacial design of liquid crystal (LC) based biosensors. The first advance revolves around the design and modulation of LC based interfaces for developing LC based stimuli responsive materials. For example, designing nanostructured thin films of LC-based colloidal gels exhibit the sensitivity and specificity with the added benefits of mechanical robustness and processability and can be used to report adsorption of biological and synthetic amphiphiles at aqueous-LC interfaces. In addition, a new pathway for the easy formation of spontaneous uniform LC droplets has been reported that provides a high spatial resolution of micrometers with a very high sensitivity. A second development has focused on the investigations of the ordering of LCs at aqueous interfaces for qualitative and quantitative understanding of important biomolecular interactions for bedside diagnostics and laboratory applications. These important biomolecular interactions include: (i) protein endotoxin interactions as these lead to divergent effects on lipopolysaccharide (LPS)-induced responses, (ii) pH induced conformation change of cardiolipin (CL) which is known to affect a range of cellular processes and (iii) endotoxin interactions with bacterial cell wall components.Thirdly this study involves design of LC based sensors that hold promise to act as a marker for cells and cell based interactions. Overall, this review illustrates new approaches for developing LC based stimuli responsive materials that are anticipated with fundamental understanding of biomolecular interactions and provide a gateway for further advances involving LCs. Keywords IntroductionBiomolecular interactions govern the affinity and specificity of complex formation and determine their biological function which could be of enormous scientific and practical importance. The pre-requisite to understand biomolecular function in the context of life and metabolism, it is necessary to analyze interactions of biomolecules by each other. A promising approach to study these interactions is to use liquid crystalline (LC) materials since it is advantageous as many biological systems, including cell membranes, phospholipids, cholesterols, DNA and so forth, exist in LC phases (Stewart, 2003; Steward, 2004). Recently, LCs have been explored for the design of interfaces that mediate desired interactions with biological systems (Lowe and Abbott, 2012). LC materials allow label-free observations of biological phenomena as the orientational properties of LCs enable the amplification and the transduction of biologically relevant binding events at nanostructured surfaces into optical outputs visible by naked eye (Brake et al., 2003a; Lin et al., 2011;Brake and Abbott, 2002; Brake et al., 2003b; Lockwood et al., 2005; Price and Schwartz, 2008;Brake et al., 2005; Lockwood et al., 2006;Sivakumar et al., 2009;Gupta et al., 2009; Park and Abbott, 2008; Hu and Jang, 2012;Bai et al., 2014; Khan and Park, 2014;Sadati et al....

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“…Instead of forming planar LC-aqueous interface, LCs can be emulsified to form LC droplets [53][54][55][56][57][58][59][60][61][62][63]. Nematic 5CB in liquid form at room temperature again becomes a good choice of making LC droplets/emulsions.…”

Section: Lc Dropletsmentioning

confidence: 99%

Beyond displays: The recent progress of liquid crystals for bio/chemical detections

Dong

Yang

2013

Chin. Sci. Bull.

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Liquid crystals (LCs) are often known as electronic displays and have become ubiquitous in our daily life, apart from that, in the past 10 years, LCs have been investigated as exquisitely sensitive reporters for developing new molecular sensing and detection tools. The unique and primary advantage of this class of intriguing materials is the perturbation of the local ordering LCs at molecular scale by bio/chemical species can be communicated within LC molecules and extended over microns, allowing the observation of the optical signals by microscope or even the naked eye. Therefore, it provides a new platform for developing bio/chemical detection and potentially label-free sensing systems. In March 1888, a young botanist called Friedrich Reinitzer [1] first found that esters of cholesterol appeared to have two melting points between which the liquid showed iridescent colors and birefringence. Actually he discovered a new phase of matter: a liquid crystalline phase, distinguished from solids, liquids and gases that are already familiar to us [2]. Substances in this fourth state are called liquid crystals (LCs), flowing like a conventional liquid and exhibiting orientational order like a crystalline solid. In general, the molecules forming LCs are anisotropic, either rod-like or disc-like. There are two basic classes of LCs: thermotropic and lyotropic. In the thermotropic system, the liquid crystalline phase only exists within a particular temperature range, between a melting point, T m , and an upper transition temperature, T c (Figure 1). In the lyotropic system, LCs possess polar and non-polar parts within the same molecule. In a certain concentration range, molecules organize themselves into ordered structures showing LC properties. This review will not discuss lyotropes further and focus on thermotropic LCs, especially 4-cyano-4′-pentylbiphenyl (5CB), which exhibits liquid crystallinity in the nematic phase at room temperature, a simple and handy choice for constructing optical detectors performed at ambient condition. The key principle of employing LCs for molecular detection is illustrated in Figure 2. The local interruption of LC ordering at the molecular scale can be amplified to micron

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Polyelectrolyte-coated liquid crystal droplets for detecting charged macromolecules

Cited by 50 publications

References 39 publications

Analysis of the Internal Configurations of Droplets of Liquid Crystal Using Flow Cytometry

Analysis of the Internal Configurations of Droplets of Liquid Crystal Using Flow Cytometry

Liquid Crystal Biosensors: New Approaches

Beyond displays: The recent progress of liquid crystals for bio/chemical detections

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