1
|
Ahn JS, Jang CH. Sensitive detection of 17β-estradiol at a picomolar level using an aptamer-assisted liquid crystal-based optical sensor. Anal Bioanal Chem 2023; 415:6323-6332. [PMID: 37581706 DOI: 10.1007/s00216-023-04907-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 08/01/2023] [Accepted: 08/03/2023] [Indexed: 08/16/2023]
Abstract
A liquid crystal (LC)-based aptasensor was developed that can detect 17β-estradiol (E2) at the picomolar level. This aptasensor is based on competitive reactions of the aptamer that interacts with cetyl trimethyl ammonium bromide (CTAB) and E2 at the aqueous/LC interface. The long alkyl chain of CTAB anchored the 4-cyano-4'-pentylbiphenyl (5CB) to a homeotropic state and controls the local anchoring depending on the extent of electrostatic interaction with the aptamer. Upon addition of the aptamer solution to the CTAB-saturated LC layer, LCs change from dark to bright optical response. This is due to the perturbed orientation of 5CB at the aqueous/LC interface as a result of electrostatic attraction of the cationic group of CTAB and the phosphate group of the aptamer. The conformational change of the aptamer due to specific binding with E2 weakens the electrostatic attraction between CTAB and aptamer. When specific binding becomes relatively dominant, CTAB induces the orientation of LCs to the homeotropic state, resulting in a dark optical image observed. We also analyzed the change in the optical response of LCs according to the interfacial events and compared the grayscale values of the optical image for each concentration of E2 to determine the detection limit. Accordingly, the detection limit of the E2 sensor was found to be 3.1 pM (0.8 pg/ml) in Tris-buffered saline (TBS), and 6.8 pM (1.9 pg/ml) in human urine. The LC-based optical aptasensor was thus shown to be highly sensitive and selective with no requirement for complex analysis equipment.
Collapse
Affiliation(s)
- Jun-Seong Ahn
- Department of Chemistry, Gachon University, Seongnam-daero 1342, Sujeong-Gu, Seongnam-Si, Gyeonggi-Do, 13120, Republic of Korea
| | - Chang-Hyun Jang
- Department of Chemistry, Gachon University, Seongnam-daero 1342, Sujeong-Gu, Seongnam-Si, Gyeonggi-Do, 13120, Republic of Korea.
| |
Collapse
|
2
|
State-of-the-Art Development in Liquid Crystal Biochemical Sensors. BIOSENSORS 2022; 12:bios12080577. [PMID: 36004973 PMCID: PMC9406035 DOI: 10.3390/bios12080577] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 07/23/2022] [Accepted: 07/26/2022] [Indexed: 12/31/2022]
Abstract
As an emerging stimuli-responsive material, liquid crystal (LC) has attracted great attentions beyond display applications, especially in the area of biochemical sensors. Its high sensitivity and fast response to various biological or chemical analytes make it possible to fabricate a simple, real-time, label-free, and cost-effective LC-based detection platform. Advancements have been achieved in the development of LC-based sensors, both in fundamental research and practical applications. This paper briefly reviews the state-of-the-art research on LC sensors in the biochemical field, from basic properties of LC material to the detection mechanisms of LC sensors that are categorized into LC-solid, LC–aqueous, and LC droplet platforms. In addition, various analytes detected by LCs are presented as a proof of the application value, including metal ions, nucleic acids, proteins, glucose, and some toxic chemical substances. Furthermore, a machine-learning-assisted LC sensing platform is realized to provide a foundation for device intelligence and automatization. It is believed that a portable, convenient, and user-friendly LC-based biochemical sensing device will be achieved in the future.
Collapse
|
3
|
Duong DST, Jang CH. Determination of chlorothalonil levels through inhibitory effect on papain activity at protein-decorated liquid crystal interfaces. Mikrochim Acta 2022; 189:292. [PMID: 35879491 PMCID: PMC9313939 DOI: 10.1007/s00604-022-05396-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Accepted: 06/22/2022] [Indexed: 11/11/2022]
Abstract
A liquid crystal (LC)-based assay was developed to detect chlorothalonil (CHL). The detection principle is based on (i) the electrostatic interaction between the positively charged protein protamine (PRO) with the negatively charged phospholipid dioleoyl-sn-glycero-3-phospho-rac-(1-glycerol) sodium salt (DOPG) and (ii) the CHL-mediated inhibition of papain (PAP) activity. The aqueous/LC interface was decorated with a monolayer of DOPG and PRO that self-assembled via electrostatic interactions. PAP can hydrolyze PRO, resulting in the realignment of an LC by DOPG, inducing a shift in the LC response from bright to dark. The addition of CHL can inhibit the activity of PAP, leading to the attraction of PRO to DOPG and the consequent disruption of the LC orientation. The orientation change of the LC in the presence or absence of CHL can be observed from the changes in its optical appearance using a polarized light microscope. Under optimal conditions, the developed assay achieved a detection limit of 0.196 pg mL-1 within a range of determination of 0.65-200 pg mL-1. The selectivity of the assay was verified in the presence of carbendazim and imidacloprid. The practical application of the proposed assay was demonstrated by its use to determine the levels of CHL in food extracts and environmental samples, which yielded recoveries and relative standard deviations (RSD) in the ranges of 87.39-99.663% and 1.03-6.32%, respectively.
Collapse
Affiliation(s)
- Duong Song Thai Duong
- Department of Chemistry, Gachon University, San 65, Bokjeong-Dong, Sujeong-Gu, Seongnam-City, Gyeonggi-Do, 461-701, South Korea
| | - Chang-Hyun Jang
- Department of Chemistry, Gachon University, San 65, Bokjeong-Dong, Sujeong-Gu, Seongnam-City, Gyeonggi-Do, 461-701, South Korea.
| |
Collapse
|
4
|
Rajesh R, Gangwar LK, Mishra SK, Choudhary A, Biradar AM, Sumana G. Technological Advancements in Bio‐recognition using Liquid Crystals: Techniques, Applications, and Performance. LUMINESCENCE 2022. [PMID: 35347826 DOI: 10.1002/bio.4242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 03/20/2022] [Accepted: 03/23/2022] [Indexed: 11/10/2022]
Abstract
The application of liquid crystal (LC) materials has undergone a modern-day renaissance from its classical use in electronics industry as display devices to new-fangled techniques for optically detecting biological and chemical analytes. This review article deals with the emergence of LC materials as invaluable material for their use as label-free sensing elements in the development of optical, electro-optical and electrochemical biosensors. The property of LC molecules to change their orientation on perturbation by any external stimuli or on interaction with bioanalytes or chemical species has been utilized by many researches for the fabrication of high sensitive LC-biosensors. In this review article we categorized LC-biosensor based on biomolecular reaction mechanism viz. enzymatic, nucleotides and immunoreaction in conjunction with operating principle at different LC interface namely LC-solid, LC-aqueous and LC-droplets. Based on bimolecular reaction mechanism, the application of LC has been delineated with recent progress made in designing of LC-interface for the detection of bio and chemical analytes of proteins, virus, bacteria, clinically relevant compounds, heavy metal ions and environmental pollutants. The review briefly describes the experimental set-ups, sensitivity, specificity, limit of detection and linear range of various viable and conspicuous LC-based biosensor platforms with associated advantages and disadvantages therein.
Collapse
Affiliation(s)
- Rajesh Rajesh
- CSIR‐National Physical Laboratory, Dr. K. S. Krishnan Marg New Delhi India
- Academy of Scientific and Innovative Research (AcSIR) Gaziabad India
| | - Lokesh K. Gangwar
- CSIR‐National Physical Laboratory, Dr. K. S. Krishnan Marg New Delhi India
- Academy of Scientific and Innovative Research (AcSIR) Gaziabad India
| | | | - Amit Choudhary
- Physics Department Deshbandhu College (University of Delhi) Kalkaji New Delhi India
| | - Ashok M. Biradar
- CSIR‐National Physical Laboratory, Dr. K. S. Krishnan Marg New Delhi India
- Academy of Scientific and Innovative Research (AcSIR) Gaziabad India
| | - Gajjala Sumana
- CSIR‐National Physical Laboratory, Dr. K. S. Krishnan Marg New Delhi India
- Academy of Scientific and Innovative Research (AcSIR) Gaziabad India
| |
Collapse
|
5
|
Label-Free, Color-Indicating, Polarizer-Free Dye-Doped Liquid Crystal Microfluidic Polydimethylsiloxane Biosensing Chips for Detecting Albumin. Polymers (Basel) 2021; 13:polym13162587. [PMID: 34451126 PMCID: PMC8401794 DOI: 10.3390/polym13162587] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2021] [Revised: 08/01/2021] [Accepted: 08/02/2021] [Indexed: 12/12/2022] Open
Abstract
We reveal a novel design for dye-doped liquid crystal (DDLC) microfluidic biosensing chips in the polydimethylsiloxane material. With this design chip, the orientation of DDLCs was affected by the interface between the walls of the channels and DDLCs. When the inside of a channel was coated with an N,N-dimethyl-n-octadecyl-3-aminopropyltrimethoxysilyl chloride (DMOAP) alignment layer, the DDLCs oriented homeotropically in a homeotropic (H) state under cross-polarized microscopy. After immobilization of antigens with antibodies on the alignment layer-coated microchannel walls, the optical intensity of the DDLC change from the dark H state to the bright planar (P) state. Using pressure-driven flow, the binding of antigens/antibodies to the DDLCs could be detected in an experimental sequential order. The microfluidic DDLCs were tested by detecting bovine serum albumin (BSA) and its immune-responses of antigens/antibodies. We proved that this immunoassay chip was able to detect BSA antigens/antibodies pairs with the detection limit about 0.5 µg/mL. The novel DDLC chip was shown to be a simple, multi-detection device, and label-free microfluidic chips are presented.
Collapse
|
6
|
Sensitive, Color-Indicating and Labeling-Free Multi-Detection Cholesteric Liquid Crystal Biosensing Chips for Detecting Albumin. Polymers (Basel) 2021; 13:polym13091463. [PMID: 34062757 PMCID: PMC8125184 DOI: 10.3390/polym13091463] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 04/24/2021] [Accepted: 04/26/2021] [Indexed: 01/10/2023] Open
Abstract
A novel device for cholesteric liquid crystal (CLC)-based microfluidic chips, accommodated in a polydimethylsiloxane material, was invented. In this device, the reorientation of the CLCs was consistently influenced by the surface of the four channel walls and adjacent CLCs. When the inside of the microchannel was coated with the alignment layer, the CLCs oriented homeotropically in a focal conic state under cross-polarizers. Once antigens had bound onto antibodies immobilized onto the orientation sheet-coated channel walls, the light intensity of the CLC molecules converted from a focal conic state to a bright planar state caused by disrupting the CLCs. By means of utilizing pressure-propelling flow, the attachment of antigen/antibody to the CLCs should be detectable within consecutive sequences. The multi-microfluidic CLC-based chips were verified by measuring bovine serum albumin (BSA) and immune complexes of pairs of BSA antigen/antibody. We showed that the multiple microfluidic immunoassaying can be used for measuring BSA and pairs of antigen/antibody BSA with a detection limit of about 1 ng/mL. The linear range is 0.1 μg/mL–1 mg/mL. A limit of immune detection of pairs of BSA antigens/antibodies was 10 ng/mL of BSA plus 1000 ng/mL of the anti-BSA antibodies was observed. According to this innovative creation of immunoassaying, an unsophisticated multi-detection device with CLC-based labeling-free microfluidic chips is presented.
Collapse
|
7
|
Bagnani M, Azzari P, De Michele C, Arcari M, Mezzenga R. Elastic constants of biological filamentous colloids: estimation and implications on nematic and cholesteric tactoid morphologies. SOFT MATTER 2021; 17:2158-2169. [PMID: 33443281 DOI: 10.1039/d0sm01886d] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Biological liquid crystals, originating from the self-assembly of biological filamentous colloids, such as cellulose and amyloid fibrils, show a complex lyotropic behaviour that is extremely difficult to predict and characterize. Here we analyse the liquid crystalline phases of amyloid fibrils, and sulfated and carboxylated cellulose nanocrystals and measure their Frank-Oseen elastic constants K1, K2 and K3 by four different approaches. The first two approaches are based on the benchmark of the predictions of: (i) a scaling form and (ii) a variational form of the Frank-Oseen energy functional with the experimental critical volumes at order-order liquid crystalline transitions of the tactoids. The third and the fourth methods imply: (iii) the direct scaling equations of elastic constants and (iv) a molecular theory predicting the elastic constants from the experimentally accessible contour length distributions of the filamentous colloids. These three biological systems exhibit diverse liquid crystalline behaviour, governed by the distinct elastic constants characterizing each colloid. Differences and similarities among the three systems are highlighted and interpreted based on the present analysis, providing a general framework to study dispersed liquid crystalline systems.
Collapse
Affiliation(s)
- Massimo Bagnani
- ETH Zurich, Department of Health Sciences and Technology, Schmelzbergstrasse 9, LFO E23 Zurich 8092, Switzerland
| | - Paride Azzari
- ETH Zurich, Department of Health Sciences and Technology, Schmelzbergstrasse 9, LFO E23 Zurich 8092, Switzerland
| | - Cristiano De Michele
- "Sapienza" Universita' di Roma, Dipartimento di Fisica, P.le A. Moro 2, 00185 Roma, Italy
| | - Mario Arcari
- ETH Zurich, Department of Health Sciences and Technology, Schmelzbergstrasse 9, LFO E23 Zurich 8092, Switzerland
| | - Raffaele Mezzenga
- ETH Zurich, Department of Health Sciences and Technology, Schmelzbergstrasse 9, LFO E23 Zurich 8092, Switzerland and ETH Zurich, Department of Materials, Wolfgang-Pauli-Strasse 10, Zurich 8093, Switzerland.
| |
Collapse
|
8
|
Paterson DA, Bao P, Abou-Saleh RH, Peyman SA, Jones JC, Sandoe JAT, Evans SD, Gleeson HF, Bushby RJ. Control of Director Fields in Phospholipid-Coated Liquid Crystal Droplets. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:6436-6446. [PMID: 32392071 DOI: 10.1021/acs.langmuir.0c00651] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
In liquid crystal (LC) droplets, small changes in surface anchoring energy can produce large changes in the director field which result in readily detectable optical effects. This makes them attractive for use as biosensors. Coating LC droplets with a phospholipid monolayer provides a bridge between the hydrophobic world of LCs and the water-based world of biology and makes it possible to incorporate naturally occurring biosensor systems. However, phospholipids promote strong perpendicular (homeotropic) anchoring that can inhibit switching of the director field. We show that the tendency for phospholipid layers to promote perpendicular anchoring can be suppressed by using synthetic phospholipids in which the acyl chains are terminated with bulky tert-butyl or ferrocenyl groups; the larger these end-group(s), the less likely the system is to be perpendicular/radial. Additionally, the droplet director field is found to be dependent on the nature of the LC, particularly its intrinsic surface properties, but not (apparently) on the sign of the dielectric anisotropy, the proximity to the melting/isotropic phase transition, the surface tension (in air), or the values of the Frank elastic constants.
Collapse
Affiliation(s)
- Daniel A Paterson
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U.K
- School of Chemistry, University of Leeds, Leeds LS2 9JT, U.K
| | - Peng Bao
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U.K
| | - Radwa H Abou-Saleh
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U.K
- Biophysics Group, Department of Physics, Faculty of Science, Mansoura University, Mansoura, Egypt
| | - Sally A Peyman
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U.K
- School of Medicine, University of Leeds, Leeds LS2 9JT, U.K
| | - J Cliff Jones
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U.K
| | - Jonathan A T Sandoe
- Leeds Institute of Medical Research, University of Leeds, Leeds LS2 9JT, U.K
| | - Stephen D Evans
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U.K
| | - Helen F Gleeson
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U.K
| | | |
Collapse
|
9
|
Esteves C, Ramou E, Porteira ARP, Barbosa AJM, Roque ACA. Seeing the Unseen: The Role of Liquid Crystals in Gas-Sensing Technologies. ADVANCED OPTICAL MATERIALS 2020; 8:1902117. [PMID: 32612901 PMCID: PMC7329384 DOI: 10.1002/adom.201902117] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Accepted: 02/17/2020] [Indexed: 05/17/2023]
Abstract
Fast, real-time detection of gases and volatile organic compounds (VOCs) is an emerging research field relevant to most aspects of modern society, from households to health facilities, industrial units, and military environments. Sensor features such as high sensitivity, selectivity, fast response, and low energy consumption are essential. Liquid crystal (LC)-based sensors fulfill these requirements due to their chemical diversity, inherent self-assembly potential, and reversible molecular order, resulting in tunable stimuliresponsive soft materials. Sensing platforms utilizing thermotropic uniaxial systems-nematic and smectic-that exploit not only interfacial phenomena, but also changes in the LC bulk, are demonstrated. Special focus is given to the different interaction mechanisms and tuned selectivity toward gas and VOC analytes. Furthermore, the different experimental methods used to transduce the presence of chemical analytes into macroscopic signals are discussed and detailed examples are provided. Future perspectives and trends in the field, in particular the opportunities for LC-based advanced materials in artificial olfaction, are also discussed.
Collapse
Affiliation(s)
- Carina Esteves
- UCIBIO, Departamento de Química Faculdade de Ciências e Tecnologia Universidade Nova de Lisboa Caparica 2829-516, Portugal
| | - Efthymia Ramou
- UCIBIO, Departamento de Química Faculdade de Ciências e Tecnologia Universidade Nova de Lisboa Caparica 2829-516, Portugal
| | - Ana Raquel Pina Porteira
- UCIBIO, Departamento de Química Faculdade de Ciências e Tecnologia Universidade Nova de Lisboa Caparica 2829-516, Portugal
| | - Arménio Jorge Moura Barbosa
- UCIBIO, Departamento de Química Faculdade de Ciências e Tecnologia Universidade Nova de Lisboa Caparica 2829-516, Portugal
| | - Ana Cecília Afonso Roque
- UCIBIO, Departamento de Química Faculdade de Ciências e Tecnologia Universidade Nova de Lisboa Caparica 2829-516, Portugal
| |
Collapse
|
10
|
Rastogi A, Pandey FP, Hegde G, Manohar R. Time-resolved fluorescence and UV absorbance study on Elaeis guineensis/oil palm leaf based carbon nanoparticles doped in nematic liquid crystals. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2020.112773] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
|
11
|
Label-Free Multi-Microfluidic Immunoassays with Liquid Crystals on Polydimethylsiloxane Biosensing Chips. Polymers (Basel) 2020; 12:polym12020395. [PMID: 32050563 PMCID: PMC7077641 DOI: 10.3390/polym12020395] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 01/29/2020] [Accepted: 01/30/2020] [Indexed: 11/17/2022] Open
Abstract
We developed a new format for liquid crystal (LC)-based multi-microfluidic immunoassays, hosted on a polydimethylsiloxane substrate. In this design, the orientations of the LCs were strongly affected by the interface between the four microchannel walls and surrounding LCs. When the alignment layer was coated inside a microchannel, the LCs oriented homeotropically and appeared dark under crossed polarizers. After antigens bound to the immobilized antibodies on the alignment layer were coated onto the channel walls, the light intensity of the LC molecules changed from dark to bright because of disruption of the LCs. By employing pressure-driven flow, binding of the antigen/antibody could be detected by optical signals in a sequential order. The multi-microfluidic LC biosensor was tested by detecting bovine serum albumin (BSA) and an immunocomplex of BSA antigen/antibody pairs, a protein standard commonly used in labs. We show that this multi-microfluidic immunoassay was able to detect BSA and antigen/antibody BSA pairs with a naked-eye detection limitation of −0.01 µg/mL. Based on this new immunoassay design, a simple and robust device for LC-based label-free microfluidic immunodetection was demonstrated.
Collapse
|
12
|
Sargazi M, Linford MR, Kaykhaii M. Liquid Crystals in Analytical Chemistry: A Review. Crit Rev Anal Chem 2018; 49:243-255. [DOI: 10.1080/10408347.2018.1512399] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- Mona Sargazi
- Department of Chemistry, Faculty of Sciences, University of Sistan and Baluchestan, Zahedan, Iran
| | - Matthew R. Linford
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT, USA
| | - Massoud Kaykhaii
- Department of Chemistry, Faculty of Sciences, University of Sistan and Baluchestan, Zahedan, Iran
| |
Collapse
|
13
|
Kim YK, Huang Y, Tsuei M, Wang X, Gianneschi NC, Abbott NL. Multi-Scale Responses of Liquid Crystals Triggered by Interfacial Assemblies of Cleavable Homopolymers. Chemphyschem 2018; 19:2037-2045. [PMID: 29682873 DOI: 10.1002/cphc.201800106] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2018] [Indexed: 12/17/2022]
Abstract
Liquid crystals (LCs) offer the basis of stimuli-responsive materials that can amplify targeted molecular events into macroscopic outputs. However, general and versatile design principles are needed to realize the full potential of these materials. To this end, we report the synthesis of two homopolymers with mesogenic side chains that can be cleaved upon exposure to either H2 O2 (polymer P1) or UV light (polymer P2). Optical measurements reveal that the polymers dissolve in bulk LC and spontaneously assemble at nematic LC-aqueous interfaces to impose a perpendicular orientation on the LCs. Subsequent addition of H2 O2 to the aqueous phase or exposure of the LC to UV was shown to trigger a surface-driven ordering transition to a planar orientation and an accompanying macroscopic optical output. Differences in the dynamics of the response to each stimulus are consistent with sequential processing of P1 at the LC-aqueous interface (H2 O2 ) and simultaneous transformation of P2 within the LC (UV). The versatility of the approach is demonstrated by creating stimuli-responsive LCs as films or microdroplets, and by dissolving mixtures of P1 and P2 into LCs to create LC materials that respond to two stimuli. Overall, our results validate a simple and generalizable approach to the rational design of polymers that can be used to program stimuli-responsiveness into LC materials.
Collapse
Affiliation(s)
- Young-Ki Kim
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison Madison, Wisconsin, 53706, USA
| | - Yuran Huang
- Materials Science & Engineering, University of Califonia, San Diego, La Jolla, CA 92093, USA
| | - Michael Tsuei
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison Madison, Wisconsin, 53706, USA
| | - Xin Wang
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison Madison, Wisconsin, 53706, USA
| | - Nathan C Gianneschi
- Department of Chemistry, Department of Materials Science & Engineering, and Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Nicholas L Abbott
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison Madison, Wisconsin, 53706, USA
| |
Collapse
|
14
|
Schwartz JJ, Mendoza AM, Wattanatorn N, Zhao Y, Nguyen VT, Spokoyny AM, Mirkin CA, Baše T, Weiss PS. Surface Dipole Control of Liquid Crystal Alignment. J Am Chem Soc 2016; 138:5957-67. [PMID: 27090503 DOI: 10.1021/jacs.6b02026] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Detailed understanding and control of the intermolecular forces that govern molecular assembly are necessary to engineer structure and function at the nanoscale. Liquid crystal (LC) assembly is exceptionally sensitive to surface properties, capable of transducing nanoscale intermolecular interactions into a macroscopic optical readout. Self-assembled monolayers (SAMs) modify surface interactions and are known to influence LC alignment. Here, we exploit the different dipole magnitudes and orientations of carboranethiol and -dithiol positional isomers to deconvolve the influence of SAM-LC dipolar coupling from variations in molecular geometry, tilt, and order. Director orientations and anchoring energies are measured for LC cells employing various carboranethiol and -dithiol isomer alignment layers. The normal component of the molecular dipole in the SAM, toward or away from the underlying substrate, was found to determine the in-plane LC director orientation relative to the anisotropy axis of the surface. By using LC alignment as a probe of interaction strength, we elucidate the role of dipolar coupling of molecular monolayers to their environment in determining molecular orientations. We apply this understanding to advance the engineering of molecular interactions at the nanoscale.
Collapse
Affiliation(s)
- Jeffrey J Schwartz
- California NanoSystems Institute, University of California, Los Angeles , Los Angeles, California 90095, United States.,Department of Physics & Astronomy, University of California, Los Angeles , Los Angeles, California 90095, United States
| | - Alexandra M Mendoza
- California NanoSystems Institute, University of California, Los Angeles , Los Angeles, California 90095, United States.,Department of Chemistry & Biochemistry, University of California, Los Angeles , Los Angeles, California 90095, United States
| | - Natcha Wattanatorn
- California NanoSystems Institute, University of California, Los Angeles , Los Angeles, California 90095, United States.,Department of Chemistry & Biochemistry, University of California, Los Angeles , Los Angeles, California 90095, United States
| | - Yuxi Zhao
- California NanoSystems Institute, University of California, Los Angeles , Los Angeles, California 90095, United States.,Department of Chemistry & Biochemistry, University of California, Los Angeles , Los Angeles, California 90095, United States
| | - Vinh T Nguyen
- Department of Chemistry & Biochemistry, University of California, Los Angeles , Los Angeles, California 90095, United States
| | - Alexander M Spokoyny
- Department of Chemistry & Biochemistry, University of California, Los Angeles , Los Angeles, California 90095, United States.,Department of Chemistry and the International Institute for Nanotechnology, Northwestern University , Evanston, Illinois 60208, United States
| | - Chad A Mirkin
- Department of Chemistry and the International Institute for Nanotechnology, Northwestern University , Evanston, Illinois 60208, United States
| | - Tomáš Baše
- Institute of Inorganic Chemistry, Academy of Sciences of the Czech Republic, v.v.i. , č.p. 1001, 250 68 Husinec-Řež, Czech Republic
| | - Paul S Weiss
- California NanoSystems Institute, University of California, Los Angeles , Los Angeles, California 90095, United States.,Department of Chemistry & Biochemistry, University of California, Los Angeles , Los Angeles, California 90095, United States.,Department of Materials Science & Engineering, University of California, Los Angeles , Los Angeles, California 90095, United States
| |
Collapse
|
15
|
DeBenedictis A, Atherton TJ, Anquetil-Deck C, Cleaver DJ, Emerson DB, Wolak M, Adler JH. Competition of lattice and basis for alignment of nematic liquid crystals. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 92:042501. [PMID: 26565259 DOI: 10.1103/physreve.92.042501] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Indexed: 06/05/2023]
Abstract
Due to elastic anisotropy, two-dimensional patterning of substrates can promote weak azimuthal alignment of adjacent nematic liquid crystals. Here we consider how such alignment can be achieved using a periodic square lattice of circular or elliptical motifs. In particular, we examine ways in which the lattice and motif can combine to favor differing orientations. Using Monte Carlo simulation and continuum elasticity we find, for circular motifs, that the coverage fraction controls both the polar anchoring angle and a transition in the azimuthal orientation. If the circles are generalized to ellipses, arbitrary control of the effective easy axis and effective anchoring potential becomes achievable by appropriate tuning of the ellipse motif relative to the periodic lattice patterning. This has possible applications in both monostable and bistable liquid crystal device contexts.
Collapse
Affiliation(s)
- Andrew DeBenedictis
- Department of Physics and Astronomy, Tufts University, 574 Boston Avenue, Medford, Massachusetts 02155, USA
| | - Timothy J Atherton
- Department of Physics and Astronomy, Tufts University, 574 Boston Avenue, Medford, Massachusetts 02155, USA
| | - Candy Anquetil-Deck
- Materials and Engineering Research Institute, Sheffield Hallam University, City Campus, Howard Street, Sheffield S1 1WB, United Kingdom
| | - Douglas J Cleaver
- Materials and Engineering Research Institute, Sheffield Hallam University, City Campus, Howard Street, Sheffield S1 1WB, United Kingdom
| | - David B Emerson
- Department of Mathematics, Tufts University, 503 Boston Avenue, Medford, Massachusetts 02155, USA
| | - Mathew Wolak
- Department of Mathematics, Tufts University, 503 Boston Avenue, Medford, Massachusetts 02155, USA
| | - James H Adler
- Department of Mathematics, Tufts University, 503 Boston Avenue, Medford, Massachusetts 02155, USA
| |
Collapse
|
16
|
Chen CH, Lin YC, Chang HH, Lee ASY. Ligand-Doped Liquid Crystal Sensor System for Detecting Mercuric Ion in Aqueous Solutions. Anal Chem 2015; 87:4546-51. [DOI: 10.1021/acs.analchem.5b00675] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Chih-Hsin Chen
- Department of Chemistry, Tamkang University, New Taipei City 25137, Taiwan
| | - Yi-Cheng Lin
- Department of Chemistry, Tamkang University, New Taipei City 25137, Taiwan
| | - Hao-Hsiang Chang
- Department of Chemistry, Tamkang University, New Taipei City 25137, Taiwan
| | - Adam Shih-Yuan Lee
- Department of Chemistry, Tamkang University, New Taipei City 25137, Taiwan
| |
Collapse
|
17
|
Zhu Q, Yang KL. Microfluidic immunoassay with plug-in liquid crystal for optical detection of antibody. Anal Chim Acta 2014; 853:696-701. [PMID: 25467520 DOI: 10.1016/j.aca.2014.08.039] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Revised: 08/14/2014] [Accepted: 08/15/2014] [Indexed: 11/25/2022]
Abstract
Recent advance in liquid crystal (LqC) based immunoassays enables label-free detection of antibody, but manual preparation of LqC cells and injection of LqC are required. In this work, we developed a new format of LqC-based immunoassay which is hosted in a microfluidic device. In this format, the orientations of LqC are strongly influenced by four channel walls surrounding the LqC. When the aspect ratio (depth/width) of the channel is smaller than 0.38, LqC orients homeotropically inside the microchannel and appears dark. After antigens bind to immobilized antibodies on the channel walls, a shift of the LqC appearance from dark to bright (due to the disruption of LqC orientation) can be visualized directly. To streamline the immunoassay process, a tubing cartridge loaded with a sample solution, washing buffers and a plug of LqC is connected to the microfluidic device. By using pressure-driven flow, the cartridge allows antigen/antibody binding, washing and optical detection to be accomplished in a sequential order. We demonstrate that this microfluidic immunoassay is able to detect anti-rabbit IgG with a naked-eye detection limit down to 1 μg mL(-1). This new format of immunoassay provides a simple and robust approach to perform LqC-based label-free immunodetection in microfluidic devices.
Collapse
Affiliation(s)
- Qingdi Zhu
- Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, 117585, Singapore
| | - Kun-Lin Yang
- Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, 117585, Singapore.
| |
Collapse
|
18
|
Verani CN, Driscoll J, Keyes PH, Heeg MJ. Cationic Copper(II)-containing Surfactants: Molecular Structures, Film Morphology, and Influence on the Alignment of Nematic Mesogens. Inorg Chem 2014; 53:5647-55. [DOI: 10.1021/ic5004098] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Cláudio N. Verani
- Department of Chemistry and ‡Department of Physics and Astronomy, Wayne State University, 5101 Cass Avenue, Room 161, Detroit, Michigan 48202, United States
| | - Jeffery Driscoll
- Department of Chemistry and ‡Department of Physics and Astronomy, Wayne State University, 5101 Cass Avenue, Room 161, Detroit, Michigan 48202, United States
| | - Paul H. Keyes
- Department of Chemistry and ‡Department of Physics and Astronomy, Wayne State University, 5101 Cass Avenue, Room 161, Detroit, Michigan 48202, United States
| | - Mary Jane Heeg
- Department of Chemistry and ‡Department of Physics and Astronomy, Wayne State University, 5101 Cass Avenue, Room 161, Detroit, Michigan 48202, United States
| |
Collapse
|
19
|
Joshi AA, Whitmer JK, Guzmán O, Abbott NL, de Pablo JJ. Measuring liquid crystal elastic constants with free energy perturbations. SOFT MATTER 2014; 10:882-893. [PMID: 24837037 DOI: 10.1039/c3sm51919h] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A first principles method is proposed to calculate the Frank elastic constants of nematic liquid crystals. These include the constants corresponding to standard splay, twist and bend deformations, and an often-ignored surface-like contribution known as saddle-splay. The proposed approach is implemented on the widely studied Gay-Berne (3, 5, 2, 1) model [J. G. Gay and B. J. Berne, J. Chem. Phys., 1981, 74, 3316], and the effects of temperature and system size on the elastic constants are examined in the nematic phase. The results of simulations for splay, twist, and bend elastic constants are consistent with those from previous literature reports. The method is subsequently applied to the saddle-splay elastic constant k24 which is found to exist at the limits of the Ericksen inequalities governing positive definite free energy. Finally, extensions of the method are discussed that present a new paradigm for in silico measurements of elastic constants.
Collapse
Affiliation(s)
- Abhijeet A Joshi
- Department of Chemical and Biological Engineering, University of Wisconsin, Madison, Wisconsin 53706, USA
| | | | | | | | | |
Collapse
|
20
|
Chan CPY, Mak WC, Cheung KY, Sin KK, Yu CM, Rainer TH, Renneberg R. Evidence-based point-of-care diagnostics: current status and emerging technologies. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2013; 6:191-211. [PMID: 23527548 DOI: 10.1146/annurev-anchem-062012-092641] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Point-of-care (POC) diagnostics brings tests nearer to the site of patient care. The turnaround time is short, and minimal manual interference enables quick clinical management decisions. Growth in POC diagnostics is being continuously fueled by the global burden of cardiovascular and infectious diseases. Early diagnosis and rapid initiation of treatment are crucial in the management of such patients. This review provides the rationale for the use of POC tests in acute coronary syndrome, heart failure, human immunodeficiency virus, and tuberculosis. We also consider emerging technologies that are based on advanced nanomaterials and microfluidics, improved assay sensitivity, miniaturization in device design, reduced costs, and high-throughput multiplex detection, all of which may shape the future development of POC diagnostics.
Collapse
Affiliation(s)
- Cangel Pui Yee Chan
- Accident and Emergency Medicine Academic Unit, Department of Medicine and Therapeutics, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, NT, Hong Kong SAR
| | | | | | | | | | | | | |
Collapse
|
21
|
Miller DS, Carlton RJ, Mushenheim PC, Abbott NL. Introduction to optical methods for characterizing liquid crystals at interfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:3154-69. [PMID: 23347378 PMCID: PMC3711186 DOI: 10.1021/la304679f] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
This Instructional Review describes methods and underlying principles that can be used to characterize both the orientations assumed spontaneously by liquid crystals (LCs) at interfaces and the strength with which the LCs are held in those orientations (so-called anchoring energies). The application of these methods to several different classes of LC interfaces is described, including solid and aqueous interfaces as well as planar and nonplanar interfaces (such as those that define a LC-in-water emulsion droplet). These methods, which enable fundamental studies of the ordering of LCs at polymeric, chemically functionalized, and biomolecular interfaces, are described in this Instructional Review on a level that can be easily understood by a nonexpert reader such as an undergraduate or graduate student. We focus on optical methods because they are based on instrumentation that is found widely in research and teaching laboratories.
Collapse
|
22
|
Carlton RJ, Hunter JT, Miller DS, Abbasi R, Mushenheim PC, Tan LN, Abbott NL. Chemical and biological sensing using liquid crystals. LIQUID CRYSTALS REVIEWS 2013; 1:29-51. [PMID: 24795857 PMCID: PMC4005293 DOI: 10.1080/21680396.2013.769310] [Citation(s) in RCA: 172] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The liquid crystalline state of matter arises from orientation-dependent, non-covalent interaction between molecules within condensed phases. Because the balance of intermolecular forces that underlies formation of liquid crystals is delicate, this state of matter can, in general, be easily perturbed by external stimuli (such as an electric field in a display). In this review, we present an overview of recent efforts that have focused on exploiting the responsiveness of liquid crystals as the basis of chemical and biological sensors. In this application of liquid crystals, the challenge is to design liquid crystalline systems that undergo changes in organization when perturbed by targeted chemical and biological species of interest. The approaches described below revolve around the design of interfaces that selectively bind targeted species, thus leading to surface-driven changes in the organization of the liquid crystals. Because liquid crystals possess anisotropic optical and dielectric properties, a range of different methods can be used to read out the changes in organization of liquid crystals that are caused by targeted chemical and biological species. This review focuses on principles for liquid crystal-based sensors that provide an optical output.
Collapse
Affiliation(s)
- Rebecca J Carlton
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706
| | - Jacob T Hunter
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706
| | - Daniel S Miller
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706
| | - Reza Abbasi
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706
| | - Peter C Mushenheim
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706
| | - Lie Na Tan
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706
| | - Nicholas L Abbott
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706
| |
Collapse
|
23
|
Lowe AM, Abbott NL. Liquid Crystalline Materials for Biological Applications. CHEMISTRY OF MATERIALS : A PUBLICATION OF THE AMERICAN CHEMICAL SOCIETY 2012; 24:746-758. [PMID: 22563142 PMCID: PMC3339119 DOI: 10.1021/cm202632m] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Liquid crystals have a long history of use as materials that respond to external stimuli (e.g., electrical and optical fields). More recently, a series of investigations have reported the design of liquid crystalline materials that undergo ordering transitions in response to a range of biological interactions, including interactions involving proteins, nucleic acids, viruses, bacteria and mammalian cells. A central challenge underlying the design of liquid crystalline materials for such applications is the tailoring of the interface of the materials so as to couple targeted biological interactions to ordering transitions. This review describes recent progress toward design of interfaces of liquid crystalline materials that are suitable for biological applications. Approaches addressed in this review include the use of lipid assemblies, polymeric membranes containing oligopeptides, cationic surfactant-DNA complexes, peptide-amphiphiles, interfacial protein assemblies and multi-layer polymeric films.
Collapse
Affiliation(s)
- Aaron M. Lowe
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, Wisconsin 53706
| | - Nicholas L. Abbott
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, Wisconsin 53706
| |
Collapse
|
24
|
Bai Y, Abbott NL. Enantiomeric interactions between liquid crystals and organized monolayers of tyrosine-containing dipeptides. J Am Chem Soc 2012; 134:548-58. [PMID: 22091988 PMCID: PMC3257416 DOI: 10.1021/ja2089475] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have examined the orientational ordering of nematic liquid crystals (LCs) supported on organized monolayers of dipeptides with the goal of understanding how peptide-based interfaces encode intermolecular interactions that are amplified into supramolecular ordering. By characterizing the orientations of nematic LCs (4-cyano-4'-pentylbiphenyl and TL205 (a mixture of mesogens containing cyclohexane-fluorinated biphenyls and fluorinated terphenyls)) on monolayers of l-cysteine-l-tyrosine, l-cysteine-l-phenylalanine, or l-cysteine-l-phosphotyrosine formed on crystallographically textured films of gold, we conclude that patterns of hydrogen bonds generated by the organized monolayers of dipeptides are transduced via macroscopic orientational ordering of the LCs. This conclusion is supported by the observation that the ordering exhibited by the achiral LCs is specific to the enantiomers used to form the dipeptide-based monolayers. The dominant role of the -OH group of tyrosine in dictating the patterns of hydrogen bonds that orient the LCs was also evidenced by the effects of phosphorylation of the tyrosine on the ordering of the LCs. Overall, these results reveal that crystallographic texturing of gold films can direct the formation of monolayers of dipeptides with long-range order, thus unmasking the influence of hydrogen bonding, chirality, and phosphorylation on the macroscopic orientational ordering of LCs supported on these surfaces. These results suggest new approaches based on supramolecular assembly for reporting the chemical functionality and stereochemistry of synthetic and biological peptide-based molecules displayed at surfaces.
Collapse
Affiliation(s)
- Yiqun Bai
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison WI 53705, United States
| | - Nicholas L. Abbott
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison WI 53705, United States
| |
Collapse
|
25
|
Bai Y, Abbott NL. Recent advances in colloidal and interfacial phenomena involving liquid crystals. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:5719-38. [PMID: 21090596 PMCID: PMC3089817 DOI: 10.1021/la103301d] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
This feature article describes recent advances in several areas of research involving the interfacial ordering of liquid crystals (LCs). The first advance revolves around the ordering of LCs at bio/chemically functionalized surfaces. Whereas the majority of past studies of surface-induced ordering of LCs have involved surfaces of solids that present a limited diversity of chemical functional groups (surfaces at which van der Waals forces dominate surface-induced ordering), recent studies have moved to investigate the ordering of LCs on chemically complex surfaces. For example, surfaces decorated with biomolecules (e.g., oligopeptides and proteins) and transition-metal ions have been investigated, leading to an understanding of the roles that metal-ligand coordination interactions, electrical double layers, acid-base interactions, and hydrogen bonding can play in the interfacial ordering of LCs. The opportunity to create chemically responsive LCs capable of undergoing ordering transitions in the presence of targeted molecular events (e.g., ligand exchange around a metal center) has emerged from these fundamental studies. A second advance has focused on investigations of the ordering of LCs at interfaces with immiscible isotropic fluids, particularly water. In contrast to prior studies of surface-induced ordering of LCs on solid surfaces, LC-aqueous interfaces are deformable and molecules at these interfaces exhibit high levels of mobility and thus can reorganize in response to changes in the interfacial environment. A range of fundamental investigations involving these LC-aqueous interfaces have revealed that (i) the spatial and temporal characteristics of assemblies formed from biomolecular interactions can be reported by surface-driven ordering transitions in the LCs, (ii) the interfacial phase behavior of molecules and colloids can be coupled to (and manipulated via) the ordering (and nematic elasticity) of LCs, and (iii) the confinement of LCs leads to unanticipated size-dependent ordering (particularly in the context of LC emulsion droplets). The third and final advance addressed in this article involves interactions between colloids mediated by LCs. Recent experiments involving microparticles deposited at the LC-aqueous interface have revealed that LC-mediated interactions can drive interfacial assemblies of particles through reversible ordering transitions (e.g., from 1D chains to 2D arrays with local hexagonal symmetry). In addition, recent single-nanoparticle measurements suggest that the ordering of LCs about nanoparticles differs substantially from micrometer-sized particles and that the interactions between nanoparticles mediated by the LCs are far weaker than predicted by theory (sufficiently weak that the interactions are reversible and thus enable self-assembly). Finally, LC-mediated interactions between colloidal particles have also been shown to lead to the formation of colloid-in-LC gels that possess mechanical properties relevant to the design of materials that interface with living biological systems. Overall, these three topics serve to illustrate the broad opportunities that exist to do fundamental interfacial science and discovery-oriented research involving LCs.
Collapse
Affiliation(s)
- Yiqun Bai
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison WI 53705, USA
| | - Nicholas L. Abbott
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison WI 53705, USA
| |
Collapse
|