18 research outputs found
Chiral Liquid Crystal Microdroplets for Sensing Phospholipid Amphiphiles
Designing simple, sensitive, fast, and inexpensive readout devices to detect biological molecules and biomarkers is crucial for early diagnosis and treatments. Here, we have studied the interaction of the chiral liquid crystal (CLC) and biomolecules at the liquid crystal (LC)-droplet interface. CLC droplets with high and low chirality were prepared using a microfluidic device. We explored the reconfiguration of the CLC molecules confined in droplets in the presence of 1,2-diauroyl-sn-glycero3-phosphatidylcholine (DLPC) phospholipid. Cross-polarized optical microscopy and spectrometry techniques were employed to monitor the effect of droplet size and DLPC concentration on the structural reorganization of the CLC molecules. Our results showed that in the presence of DLPC, the chiral LC droplets transition from planar to homeotropic ordering through a multistage molecular reorientation. However, this reconfiguration process in the low-chirality droplets happened three times faster than in high-chirality ones. Applying spectrometry and image analysis, we found that the change in the chiral droplets’ Bragg reflection can be correlated with the CLC–DLPC interactions
Chiral Liquid Crystal Microdroplets for Sensing Phospholipid Amphiphiles
Designing simple, sensitive, fast, and inexpensive readout devices to detect biological molecules and biomarkers is crucial for early diagnosis and treatments. Here, we have studied the interaction of the chiral liquid crystal (CLC) and biomolecules at the liquid crystal (LC)-droplet interface. CLC droplets with high and low chirality were prepared using a microfluidic device. We explored the reconfiguration of the CLC molecules confined in droplets in the presence of 1,2-diauroyl-sn-glycero3-phosphatidylcholine (DLPC) phospholipid. Cross-polarized optical microscopy and spectrometry techniques were employed to monitor the effect of droplet size and DLPC concentration on the structural reorganization of the CLC molecules. Our results showed that in the presence of DLPC, the chiral LC droplets transition from planar to homeotropic ordering through a multistage molecular reorientation. However, this reconfiguration process in the low-chirality droplets happened three times faster than in high-chirality ones. Applying spectrometry and image analysis, we found that the change in the chiral droplets’ Bragg reflection can be correlated with the CLC–DLPC interactions
LCPOM: Precise Reconstruction of Polarized Optical Microscopy Images of Liquid Crystals
When viewed with a cross-polarized optical microscope (POM), liquid crystals
display interference colors and complex patterns that depend on the material's
microscopic orientation. That orientation can be manipulated by application of
external fields, which provides the basis for applications in optical display
and sensing technologies. The color patterns themselves have a high information
content. Traditionally, however, calculations of the optical appearance of
liquid crystals have been performed by assuming that a single-wavelength light
source is employed, and reported in a monochromatic scale. In this work, the
original Jones matrix method is extended to calculate the colored images that
arise when a liquid crystal is exposed to a multi-wavelength source. By
accounting for the material properties, the visible light spectrum and the CIE
color matching functions, we demonstrate that the proposed approach produces
colored POM images that are in quantitative agreement with experimental data.
Results are presented for a variety of systems, including radial, bipolar, and
cholesteric droplets, where results of simulations are compared to experimental
microscopy images. The effects of droplet size, topological defect structure,
and droplet orientation are examined systematically. The technique introduced
here generates images that can be directly compared to experiments, thereby
facilitating machine learning efforts aimed at interpreting LC microscopy
images, and paving the way for the inverse design of materials capable of
producing specific internal microstructures in response to external stimuli.Comment: 12 pages, 5 figures (main text). 6 pages, 6 figures (appendices
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Propulsion and navigation within the advancing monolayer sheet
As a wound heals, or a body plan forms, or a tumour invades, observed cellular motions within the advancing cell swarm are thought to stem from yet to be observed physical stresses that act in some direct and causal mechanical fashion. Here we show that such a relationship between motion and stress is far from direct. Using monolayer stress microscopy, we probed migration velocities, cellular tractions and intercellular stresses in an epithelial cell sheet advancing towards an island on which cells cannot adhere. We found that cells located near the island exert tractions that pull systematically towards this island regardless of whether the cells approach the island, migrate tangentially along its edge, or paradoxically, recede from it. This unanticipated cell-patterning motif, which we call kenotaxis, represents the robust and systematic mechanical drive of the cellular collective to fill unfilled space
Chiral Liquid Crystal Microdroplets for Sensing Phospholipid Amphiphiles
Designing simple, sensitive, fast, and inexpensive readout devices to detect biological molecules and biomarkers is crucial for early diagnosis and treatments. Here, we have studied the interaction of the chiral liquid crystal (CLC) and biomolecules at the liquid crystal (LC)-droplet interface. CLC droplets with high and low chirality were prepared using a microfluidic device. We explored the reconfiguration of the CLC molecules confined in droplets in the presence of 1,2-diauroyl-sn-glycero3-phosphatidylcholine (DLPC) phospholipid. Cross-polarized optical microscopy and spectrometry techniques were employed to monitor the effect of droplet size and DLPC concentration on the structural reorganization of the CLC molecules. Our results showed that in the presence of DLPC, the chiral LC droplets transition from planar to homeotropic ordering through a multistage molecular reorientation. However, this reconfiguration process in the low-chirality droplets happened three times faster than in high-chirality ones. Applying spectrometry and image analysis, we found that the change in the chiral droplets’ Bragg reflection can be correlated with the CLC–DLPC interactions
Engineering Nano/Microscale Chiral Self-Assembly in 3D Printed Constructs
Highlights To precisely engineer complex helical hierarchies at nano/microscales, reactive inks with chiral nematic anisotropy are designed for 3D printing. The phase transformations and chiral evolution in response to parallel and orthogonal shear forces are meticulously investigated to finely adjust the 3D printing parameters for programming oriented chiral assemblies. The interplay between chiral relaxation dynamics and photo-polymerization kinetics is finely tuned to enable well-controlled chiral reformation, while simultaneously ensuring high print quality
Water Flux Induced Reorientation of Liquid Crystals
It is well understood
that the adsorption of solutes at the interface
between a bulk liquid crystal phase and an aqueous phase can lead
to orientational or anchoring transitions. A different principle is
introduced here, whereby a transient reorientation of a thermotropic
liquid crystal is triggered by a spontaneous flux of water across
the interface. A critical water flux can be generated by the addition
of an electrolyte to the bulk aqueous phase, leading to a change in
the solvent activity; water is then transported through the liquid
crystal phase and across the interface. The magnitude of the spontaneous
water flux can be controlled by the concentration and type of solutes,
as well as the rate of salt addition. These results present new, previously
unappreciated fundamental principles that could potentially be used
for the design of materials involving transient gating mechanisms,
including biological sensors, drug delivery systems, separation media,
and molecular machines