Molecular chirality detection using plasmonic and dielectric nanoparticles

Abstract Nanoscale particles and structures hold promise in circular dichroism (CD) spectroscopy for overcoming the weakness of molecular CD signals. Significant effort have been made to characterize nanophotonic CD enhancement and find efficient ways to boost molecular chirality, but the best solution is yet to be found. In this paper, we present a rigorous analytic study of the nanophotonic CD enhancement of typical nanoparticles. We consider metallic and dielectric nanoparticles capped with chiral molecules and analyze the effect of multipolar nanoparticles on the molecular CD. We identify the spectral features of the molecular CD resulting from the electric and magnetic resonances of nanoparticles and suggest better ways to boost molecular chirality. We also clarify the contribution of particle scattering and absorption to the molecular CD and the dependence on particle size. Our work provides an exact analytic approach to nanophotonic CD enhancement and offers a rule for selecting the most efficient particle for sensitive molecular chirality detection.

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Investigation of the particle size-dependent near-infrared spectral features of binary mixture samples in conjunction with Monte Carlo simulation and the influence of particle size on the accuracy of quantitative analysis

The Analyst ◽

10.1039/c8an00736e ◽

2018 ◽

Vol 143 (18) ◽

pp. 4306-4315 ◽

Cited By ~ 1

Author(s):

Pham K. Duy ◽

Seulah Chun ◽

Yoonjeong Lee ◽

Hoeil Chung

Keyword(s):

Monte Carlo Simulation ◽

Particle Size ◽

Monte Carlo ◽

Quantitative Analysis ◽

Near Infrared ◽

Spectral Variation ◽

Spectral Features ◽

Size Dependent ◽

Infrared Spectral ◽

Mixture Samples

The origin of particle size-induced near-infrared (NIR) spectral variation, which is fundamental for robust quantitative analysis, was systematically studied in conjunction with Monte Carlo simulation.

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Determination of the absolute stereostructure of a cyclic azobenzene from the crystal structure of the precursor containing a heavy element

Beilstein Journal of Organic Chemistry ◽

10.3762/bjoc.12.212 ◽

2016 ◽

Vol 12 ◽

pp. 2211-2215 ◽

Cited By ~ 2

Author(s):

Reji Thomas ◽

Nobuyuki Tamaoki

Keyword(s):

Cd Spectroscopy ◽

Chiral Molecules ◽

X Ray Diffraction ◽

X Ray ◽

Heavy Atoms ◽

Unambiguous Determination ◽

The Common ◽

The Absolute ◽

Reverse Method

Single crystal X-ray diffraction has been used as one of the common methods for the unambiguous determination of the absolute stereostructure of chiral molecules. However, this method is limited to molecules containing heavy atoms or to molecules with the possibility of functionalization with heavy elements or chiral internal references. Herein, we report the determination of the absolute stereostructure of the enantiomers of molecule (E)-2, which lacks the possibility of functionalization, using a reverse method, i.e., defunctionalization of its precursor of known stereostructure with bromine substitution (S-(−)-(E)-1). A reductive debromination of S-(−)-(E)-1 results in formation of one of the enantiomers of (E)-2. Using a combination of HPLC and CD spectroscopy we could safely assign the stereostructure of one of the enantiomers of (E)-2, the reduced product R-(−)-(E)-1.

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Nanoparticle Measurement Through Visualisation

Microscopy Today ◽

10.1017/s1551929500055887 ◽

2008 ◽

Vol 16 (2) ◽

pp. 22-25

Author(s):

Bob Carr ◽

Andrew Malloy

Keyword(s):

Particle Size ◽

Particle Number ◽

Number Concentration ◽

Sample Type ◽

Particle Number Concentration ◽

Particle Interactions ◽

Nanoparticle Tracking Analysis ◽

Nanoscale Particles ◽

Video Images ◽

Solvent Type

In this article, we will describe how nanoscale particles may be individually visualised (but not imaged) in liquids and from which higher resolution particle size distribution profiles can be obtained compared to other light scattering techniques. The method is called Nanoparticle Tracking Analysis (NTA)Sample preparation is minimal, requiring only dilution with a suitable solvent to an acceptable concentration range (between 10 and 1010 particles per ml depending on sample type). Accurate and reproducible analyses can be obtained from video images of only a few seconds duration and the results allow particle number concentration to be recovered. Given the close to real-time nature of the technique, particle-particle interactions are accessible as is information about sample aggregation and dissemination. All particle types can be measured and in any solvent type providing that the particles scatter sufficient light to be visible (i.e. are not indexed matched).

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Novel Fabrication of Zein-Soluble Soybean Polysaccharide Nanocomposites Induced by Multifrequency Ultrasound, and Their Roles on Microstructure, Rheological Properties and Stability of Pickering Emulsions

Gels ◽

10.3390/gels7040166 ◽

2021 ◽

Vol 7 (4) ◽

pp. 166

Author(s):

Teng Song ◽

Zhiyu Xiong ◽

Tong Shi ◽

Abdul Razak Monto ◽

Li Yuan ◽

...

Keyword(s):

Particle Size ◽

Binding Capacity ◽

Loss Modulus ◽

Surface Hydrophobicity ◽

Cd Spectroscopy ◽

Composite Nanoparticles ◽

Pickering Emulsions ◽

Dual Frequency ◽

Water Binding ◽

3D Network

In this work, soluble soybean polysaccharides (SSPS) were employed together with multifrequency ultrasound to fabricate zein nanocomposites which were conducive to enhancing the stability of high internal phase emulsions (HIPEs). Compared with non-ultrasonic treated zein colloidal particle samples (132.23 ± 0.85 nm), the zein nanoparticles samples induced by dual-frequency ultrasound exhibited a smaller particle size (114.54 ± 0.23 nm). Furthermore, the particle size of the zein composite nanoparticles (256.5 ± 4.81) remarkably increased with SPSS coating, consequently leading to larger fluorescence intensity together with lower zeta-potential (−21.90 ± 0.46 mv) and surface hydrophobicity (4992.15 ± 37.28). Meanwhile, zein-SSPS composite nanoparticles induced by DFU showed remarkably enhanced thermal stability. Fourier transform infrared (FTIR) spectroscopy and Circular dichroism (CD) spectroscopy were also used to characterize zein-SSPS composite nanoparticles. The results confirmed that DFU combined with SSPS treatment significantly increased β-sheets (from 12.60% ± 0.25 b to 21.53% ± 0.37 c) and reduced α-helix content (34.83% ± 0.71 b to 23.86% ± 0.66 a) remarkably. Notably, HIPEs prepared from zein-SSPS nanocomposites induced by dual-frequency simultaneous ultrasound (DFU) at 40/60 kHz showed better storage stability. HIPEs stabilized by DFU induced zein-SSPS nanoparticles exhibited higher storage modulus (G′) and loss modulus (G″), leading to lower fluidity, together with better stability contributing to the water-binding capacity and three-dimensional (3D) network structure of the HIPEs emulsion. The findings of this study indicate that this method can be utilized and integrated to further extend the application of zein and SSPS and explore HIPEs.

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No Small Risk

Mechanical Engineering ◽

10.1115/1.2006-sep-1 ◽

2006 ◽

Vol 128 (09) ◽

pp. 30-33

Author(s):

Jeffrey Winters

Keyword(s):

Particle Size ◽

Nanoscale Materials ◽

Bulk Materials ◽

Precision Control ◽

Nanoscale Particles ◽

Naturally Occurring ◽

Small Risk ◽

Wide Range ◽

Basic Parameters ◽

Combustion Exhaust

This paper assesses the risk posed by nanotech products in endangering human health. Material characteristics that have little bearing on health effects in bulk materials, such as surface area, may become important when trying to measure the hazard from trace amounts of nanomaterials. Nanotoxicologists may have to use a separate and unique set of metrics for determining what the safe exposure to various nanomaterials. The precision control that engineers have in making nanoscale materials may also amplify their effect. Naturally occurring nanoscale materials, such as particles formed in combustion exhaust, are formed over a wide range of sizes. Any given particle size will make up only a small part of the overall sample, diluting the potential ill effects. Nanoengineered materials come in a tight range of sizes. Research that helps lay out the basic parameters of the problem-figuring out which characteristics of nanoscale particles are most important.

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Unraveling the origin of chirality from plasmonic nanoparticle-protein complexes

Science ◽

10.1126/science.aax5415 ◽

2019 ◽

Vol 365 (6460) ◽

pp. 1475-1478 ◽

Cited By ~ 35

Author(s):

Qingfeng Zhang ◽

Taylor Hernandez ◽

Kyle W. Smith ◽

Seyyed Ali Hosseini Jebeli ◽

Alan X. Dai ◽

...

Keyword(s):

Circular Dichroism ◽

Protein Complexes ◽

Three Dimensional ◽

Ultrasensitive Detection ◽

Chiral Molecules ◽

Plasmonic Nanoparticle ◽

Molecular Chirality ◽

Electron Imaging ◽

Circular Dichroïsm ◽

Origin Of Chirality

Plasmon-coupled circular dichroism has emerged as a promising approach for ultrasensitive detection of biomolecular conformations through coupling between molecular chirality and surface plasmons. Chiral nanoparticle assemblies without chiral molecules present also have large optical activities. We apply single-particle circular differential scattering spectroscopy coupled with electron imaging and simulations to identify both structural chirality of plasmonic aggregates and plasmon-coupled circular dichroism induced by chiral proteins. We establish that both chiral aggregates and just a few proteins in interparticle gaps of achiral assemblies are responsible for the ensemble signal, but single nanoparticles do not contribute. We furthermore find that the protein plays two roles: It transfers chirality to both chiral and achiral plasmonic substrates, and it is also responsible for the chiral three-dimensional assembly of nanorods. Understanding these underlying factors paves the way toward sensing the chirality of single biomolecules.

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Mechanics-Based Approach for Detection and Measurement of Particle Contamination in Proximity Nanofabrication Processes

Journal of Micro and Nano-Manufacturing ◽

10.1115/1.4033742 ◽

2016 ◽

Vol 4 (3) ◽

Author(s):

Shrawan Singhal ◽

Michelle A. Grigas ◽

S. V. Sreenivasan

Keyword(s):

Particle Size ◽

Liquid Film ◽

Deleterious Effect ◽

Nanoscale Particles ◽

Optical Inspection ◽

Close Proximity ◽

Great Progress ◽

Particle Contamination ◽

Potential Contact ◽

Effect On Yield

In spite of the great progress made toward addressing the challenge of particle contamination in nanomanufacturing, its deleterious effect on yield is still not negligible. This is particularly true for nanofabrication processes that involve close proximity or contact between two or more surfaces. One such process is Jet-and-Flash Imprint Lithography (J-FIL™), which involves the formation of a nanoscale liquid film between a patterned template and a substrate. In this process, the presence of any frontside particle taller than the liquid film thickness, which is typically sub-25 nm, can not only disrupt the continuity of this liquid film but also damage the expensive template upon contact. The detection of these particles has typically relied on the use of subwavelength optical techniques such as scatterometry that can suffer from low throughput for nanoscale particles. In this paper, a novel mechanics-based method has been proposed as an alternative to these techniques. It can provide a nearly 1000 × amplification of the particle size, thereby allowing for optical microscopy based detection. This technique has been supported by an experimentally validated multiphysics model which also allows for estimation of the loss in yield and potential contact-related template damage because of the particle encounter. Also, finer inspection of template damage needs to be carried out over a much smaller area, thereby increasing throughput of the overall process. This technique also has the potential for inline integration, thereby circumventing the need for separate tooling for subwavelength optical inspection of substrates.

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The Infrared Analysis of Polyethylene Terephthalate Fibers and of Their Strength as Related to Sample Preparation and to Particle Size

Applied Spectroscopy ◽

10.1366/0003702894202085 ◽

1989 ◽

Vol 43 (5) ◽

pp. 791-794 ◽

Cited By ~ 3

Author(s):

R. O. Carter ◽

K. R. Carduner ◽

M. C. Paputa Peck ◽

D. H. Motry

Keyword(s):

Particle Size ◽

Sample Preparation ◽

Polyethylene Terephthalate ◽

Infrared Analysis ◽

Spectral Features ◽

Band Broadening ◽

Small Particles ◽

Large Particles ◽

Local Sample ◽

Infrared Microscope

An explanation is presented for the broadening of intense spectral features observed in the infrared spectra of polyethylene terephthalate fibers prepared as KBr pellets. Since band broadening occurs in the spectra of stronger, undegraded fiber, it is proposed that, the stronger the fiber, the more the difficulty one has in pulverizing the sample. Larger particles result from undegraded polyester, which lead to broader bands for intense features. The local sample pathlength in the region of the large particles is greater than that for small particles, which can be more homogeneously mixed. Fiber samples can also be presented to an infrared microscope either “as is” or flattened. Striking differences exist between spectra for flattened and round fibers that were otherwise similar.

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X-ray circular dichroism signals: a unique probe of local molecular chirality

Chemical Science ◽

10.1039/c7sc01347g ◽

2017 ◽

Vol 8 (9) ◽

pp. 5969-5978 ◽

Cited By ~ 7

Author(s):

Yu Zhang ◽

Jérémy R. Rouxel ◽

Jochen Autschbach ◽

Niranjan Govind ◽

Shaul Mukamel

Keyword(s):

Circular Dichroism ◽

Electronic Structures ◽

Chiral Molecules ◽

X Ray ◽

Molecular Chirality ◽

Unique Probe ◽

Circular Dichroïsm

X-ray circular dichroism (XCD) spectroscopy provides a powerful tool to detect subtle electronic structures of chiral molecules.

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Mineral snowflakes on exoplanets and brown dwarfs

Astronomy and Astrophysics ◽

10.1051/0004-6361/202037553 ◽

2020 ◽

Vol 639 ◽

pp. A107 ◽

Cited By ~ 1

Author(s):

D. Samra ◽

Ch. Helling ◽

M. Min

Keyword(s):

Particle Size ◽

High Resolution ◽

Particle Size Distribution ◽

Size Distribution ◽

Brown Dwarfs ◽

Spherical Particles ◽

Cloud Formation ◽

Spectral Features ◽

Spherical Cloud ◽

Cloud Particles

Context. Exoplanet atmosphere characterisation has become an important tool in understanding exoplanet formation, evolution, and it also is a window into potential habitability. However, clouds remain a key challenge for characterisation: upcoming space telescopes (e.g. the James Webb Space Telescope, JWST, and the Atmospheric Remote-sensing Infrared Exoplanet Large-survey) and ground-based high-resolution spectrographs (e.g. the next-generation CRyogenic high-resolution InfraRed Echelle Spectrograph) will produce data requiring detailed understanding of cloud formation and cloud effects for a variety of exoplanets and brown dwarfs. Aims. We aim to understand how the micro-porosity of cloud particles affects the cloud structure, particle size, and material composition on exoplanets and brown dwarfs. We further examine the spectroscopic effects of micro-porous particles, the particle size distribution, and non-spherical cloud particles. Methods. We expanded our kinetic non-equilibrium cloud formation model to study the effect of micro-porosity on the cloud structure using prescribed 1D (Tgas–pgas) profiles from the DRIFT-PHOENIX model atmosphere grid. We applied the effective medium theory and the Mie theory to model the spectroscopic properties of cloud particles with micro-porosity and a derived particle size distribution. In addition, we used a statistical distribution of hollow spheres to represent the effects of non-spherical cloud particles. Results. Highly micro-porous cloud particles (90% vacuum) have a larger surface area, enabling efficient bulk growth higher in the atmosphere than for compact particles. Increases in single scattering albedo and cross-sectional area for these mineral snowflakes cause the cloud deck to become optically thin only at a wavelength of ~100 μm instead of at the ~20 μm for compact cloud particles. A significant enhancement in albedo is also seen when cloud particles occur with a locally changing Gaussian size distribution. Non-spherical particles increase the opacity of silicate spectral features, which further increases the wavelength at which the clouds become optically thin. Conclusions. Retrievals of cloud properties, particularly particle size and mass of clouds, are biased by the assumption of compact spherical particles. The JWST mid-infrared instrument will be sensitive to signatures of micro-porous and non-spherical cloud particles based on the wavelength at which clouds are optically thin. Details of spectral features are also dependent on particle shape, and greater care must be taken in modelling clouds as observational data improves.

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