Ultrafast snapshots of terahertz electric potentials across ring-shaped quantum barriers.

Probing the time evolution of the terahertz electric field within subwavelength dimensions plays a crucial role in observing the nanoscale lightwave interactions with fundamental excitations in condensed-matter systems and in artificial structures, such as metamaterials. Here, we propose a novel probing method for measuring terahertz electric potentials across nanogaps using a combination of optical and terahertz pulse excitations. To achieve this, we employ ring-shaped nanogaps that enclose a metallic island, allowing us to capture tunneling charges when subjected to terahertz electromagnetic pulse illumination.

Shear Stress-Dependent Targeting Efficiency Using Self-Assembled Gelatin-Oleic Nanoparticles in a Biomimetic Microfluidic System.

Cellular properties and microenvironments, as well as the characteristics of nanoparticles (NPs), affect the cellular uptake and cytotoxic effects of drug-loaded NPs. Since there is fluid flow in the human blood system, fluid flow also affects the drug delivery efficiency of NPs. This study aimed to evaluate the cellular behaviors of drug-loaded soft NPs on A549 cancer cells under different levels of shear stress (0.

Terahertz rectification in ring-shaped quantum barriers.

Tunneling is the most fundamental quantum mechanical phenomenon with wide-ranging applications. Matter waves such as electrons in solids can tunnel through a one-dimensional potential barrier, e.g.

Terahertz-driven polymerization of resists in nanoantennas.

Plasmon-mediated polymerization has been intensively studied for various applications including nanolithography, near-field mapping, and selective functionalization. However, these studies have been limited from the near-infrared to the ultraviolet regime. Here, we report a resist polymerization using intense terahertz pulses and various nanoantennas.

Magnetic Nature of Light Transmission through a 5-nm Gap.

Slot antennas have been exploited as important building blocks of optical magnetism because their radiations are invoked by the magnetic fields along the axes, as vectorial Babinet principle predicts. However, optical magnetism of a few-nanometer-width slit, for which fascinating applications are found due to the colossal field enhancement but Babinet principle fails due to the nonnegligible thickness, has not been investigated. In this paper, we demonstrated that the magnetic field plays a dominant role in light transmission through a 5-nm slit on a 150-nm-thick gold film.

Terahertz Nanoprobing of Semiconductor Surface Dynamics.

Most semiconductors have surface dynamics radically different from its bulk counterpart due to surface defect, doping level, and symmetry breaking. Because of the technical challenge of direct observation of the surface carrier dynamics, however, experimental studies have been allowed in severely shrunk structures including nanowires, thin films, or quantum wells where the surface-to-volume ratio is very high. Here, we develop a new type of terahertz (THz) nanoprobing system to investigate the surface dynamics of bulk semiconductors, using metallic nanogap accompanying strong THz field confinement.

Caspase-8 controls the secretion of inflammatory lysyl-tRNA synthetase in exosomes from cancer cells.

Aminoacyl-tRNA synthetases (ARSs), enzymes that normally control protein synthesis, can be secreted and have different activities in the extracellular space, but the mechanism of their secretion is not understood. This study describes the secretion route of the ARS lysyl-tRNA synthetase (KRS) and how this process is regulated by caspase activity, which has been implicated in the unconventional secretion of other proteins. We show that KRS is secreted from colorectal carcinoma cells within the lumen of exosomes that can trigger an inflammatory response.

Investigation of biomimetic shear stress on cellular uptake and mechanism of polystyrene nanoparticles in various cancer cell lines.

Cancer cells in the tumor microenvironment are affected by fluid shear stress generated by blood flow in the vascular microenvironment and interstitial flows in the tumor microenvironment. Thus, we investigated how fluidic shear stress affects cellular uptake as well as the endocytosis mechanism of nanoparticles using a biomimetic microfluidic system that mimics the human dynamic environment. Positively charged amino-modified polystyrene nanoparticles (PSNs) at 100 μg/mL were delivered to cancer cells under static and biomimetic dynamic conditions (0.

Effect of biomimetic shear stress on intracellular uptake and cell-killing efficiency of doxorubicin in a free and liposomal formulation.

Shear stress could be considered in the context of cellular uptake and cell-killing efficiency. Thus, mimicking the dynamic characteristics of in vivo environment is important in targeted drug delivery. We investigated the intracellular uptake and cell-killing efficiency of doxorubicin (DOX) in a free and liposomal form (Doxil(®)) under biomimetic shear stress to mimic in vivo environment.

Novel Morphologic and Genetic Analysis of Cancer Cells in a 3D Microenvironment Identifies STAT3 as a Regulator of Tumor Permeability Barrier Function.

Tumor permeability is a critical determinant of drug delivery and sensitivity, but systematic methods to identify factors that perform permeability barrier functions in the tumor microenvironment are not yet available. Multicellular tumor spheroids have become tractable in vitro models to study the impact of a three-dimensional (3D) environment on cellular behavior. In this study, we characterized the spheroid-forming potential of cancer cells and correlated the resulting spheroid morphologies with genetic information to identify conserved cellular processes associated with spheroid structure.

Electromagnetic Saturation of Angstrom-Sized Quantum Barriers at Terahertz Frequencies.

Metal-graphene-metal hybrid structures allow angstrom-scale van der Waals gaps, across which electron tunneling occurs. We squeeze terahertz electromagnetic waves through these λ/10 000 000 gaps, accompanied by giant field enhancements. Unprecedented transmission reduction of 97% is achieved with the transient voltage across the gap saturating at 5 V.

Selective electric and magnetic sensitivity of aperture probes.

We report the effect of geometrical factors governing the polarization profiles of near-field scanning optical microscope (NSOM) probes. The most important physical parameter controlling the selective electric or magnetic field sensitivity is found to be the width of the metal rim surrounding aperture. Probes with metal rim width w < λ/2 selectively senses the optical electric field, while those with w > λ/2 selectively senses the optical magnetic field.

Nanoscale Single-Element Color Filters.

Visible-light filters constructed from nanostructured materials typically consist of a metallic grating and rely on the excitation of surface plasmon polaritons (SPPs). In order to operate at full efficiency, the number of grating elements needs to be maximized such that light can couple more efficiently to the SPPs through improved diffraction. Such conditions impose a limitation on the compactness of the filter since a larger number of grating elements represents a larger effective size.

Screening of quinoline, 1,3-benzoxazine, and 1,3-oxazine-based small molecules against isolated methionyl-tRNA synthetase and A549 and HCT116 cancer cells including an in silico binding mode analysis.

Elevated activity of methionyl-tRNA synthetase (MRS) in many cancers renders it a possible drug target in this disease area, as well as in a series of parasitic diseases. In the present work, we report the synthesis and in vitro screening of a library of 1,3-oxazines, benzoxazines and quinoline scaffolds against human MRS. Among the compounds tested, 2-(2-butyl-4-chloro-1-(4-phenoxybenzyl)-1H-imidazol-5-yl)-5-(4-methoxyphenyl)-1-oxa-3-azaspiro[5.

Quantum dots-nanogap metamaterials fabrication by self-assembly lithography and photoluminescence studies.

We present a new and versatile technique of self-assembly lithography to fabricate a large scale Cadmium selenide quantum dots-silver nanogap metamaterials. After optical and electron microscopic characterizations of the metamaterials, we performed spatially resolved photoluminescence transmission measurements. We obtained highly quenched photoluminescence spectra compared to those from bare quantum dots film.

Optical field enhancement of nanometer-sized gaps at near-infrared frequencies.

We report near-field and far-field measurements of transmission through nanometer-sized gaps at near-infrared frequencies with varying the gap size from 1 nm to 10 nm. In the far-field measurements, we excluded direct transmission on the metal film surface via interferometric method. Kirchhoff integral formalism was used to relate the far-field intensity to the electric field at the nanogaps.

New method and characterization of self-assembled gelatin-oleic nanoparticles using a desolvation method via carbodiimide/N-hydroxysuccinimide (EDC/NHS) reaction.

In this study, we investigated a new method for the preparation of gelatin-oleic conjugate (GOC) as an amphiphilic biomaterial to load model anti-cancer drugs into self-assembled nanoparticles (NPs). Oleic acid (OA) was covalently bound to gelatin via carbodiimide/N-hydroxysuccinimide (EDC/NHS) reaction in water-ethanol cosolvent to form a GOC. Fourier transform infrared (FT-IR) spectroscopy and proton nuclear magnetic resonance ((1)H NMR) clearly indicated the successful synthesis of GOC.

Promiscuous methionyl-tRNA synthetase mediates adaptive mistranslation to protect cells against oxidative stress.

Aminoacyl-tRNA synthetases (ARSs) acylate transfer (t)RNAs with amino acids. Charging tRNAs with the right amino acids is the first step in translation; therefore, the accurate and error-free functioning of ARSs is an essential prerequisite for translational fidelity. A recent study found that methionine (Met) can be incorporated into non-Met residues of proteins through methionylation of non-cognate tRNAs under conditions of oxidative stress.

Convergent evolution of two different random RNAs for specific interaction with methionyl-tRNA synthetase.

Aminoacyl-tRNA synthetases (ARSs) recognize a specific sequence or structural characteristics of their cognate tRNAs. To contribute to the understanding how these recognition sites were selected, we generated two different RNA libraries containing either 42mer or 70mer random sequence and used them to select RNA aptamers that specifically bound to methionyl-tRNA synthetase (MRS) of Mycobacterium tuberculosis. The aptamer pools selected from the two RNA libraries showed strong binding affinity and selectivity to M.

AIMP3/p18 controls translational initiation by mediating the delivery of charged initiator tRNA to initiation complex.

Aminoacyl-tRNA synthetase-interacting multifunctional proteins (AIMPs) are nonenzymatic scaffolding proteins that comprise multisynthetase complex (MSC) with nine aminoacyl-tRNA synthetases in higher eukaryotes. Among the three AIMPs, AIMP3/p18 is strongly anchored to methionyl-tRNA synthetase (MRS) in the MSC. MRS attaches methionine (Met) to initiator tRNA (tRNA(i)(Met)) and plays an important role in translation initiation.

Secreted human glycyl-tRNA synthetase implicated in defense against ERK-activated tumorigenesis.

Although adaptive systems of immunity against tumor initiation and destruction are well investigated, less understood is the role, if any, of endogenous factors that have conventional functions. Here we show that glycyl-tRNA synthetase (GRS), an essential component of the translation apparatus, circulates in serum and can be secreted from macrophages in response to Fas ligand that is released from tumor cells. Through cadherin (CDH)6 (K-cadherin), GRS bound to different ERK-activated tumor cells, and released phosphatase 2A (PP2A) from CDH6.

Dual role of methionyl-tRNA synthetase in the regulation of translation and tumor suppressor activity of aminoacyl-tRNA synthetase-interacting multifunctional protein-3.

Mammalian methionyl-tRNA synthetase (MRS) plays an essential role in initiating translation by transferring Met to initiator tRNA (tRNA(i)(Met)). MRS also provides a cytosolic anchoring site for aminoacyl-tRNA synthetase-interacting multifunctional protein-3 (AIMP3)/p18, a potent tumor suppressor that is translocated to the nucleus for DNA repair upon DNA damage. However, the mechanism by which this enzyme mediates these two seemingly unrelated functions is unknown.

Blockade of IL-6 secretion pathway by the sesquiterpenoid atractylenolide III.

Atractylenolide III (1) is the major bioactive component of Atractylodes lancea. The aim of this study was to analyze the effect on the regulation of interleukin (IL)-6 secretion pathway caused by 1. This sesquiterpenoid inhibited the secretion and expression of IL-6 in phorbol 12-myristate 13-acetate- and calcium ionophore A23187-stimulated human mast cells (HMC)-1.

Atractylenolide III, a sesquiterpenoid, induces apoptosis in human lung carcinoma A549 cells via mitochondria-mediated death pathway.

Pharmacological agents that are safe and can sensitize the lung cancer are urgently required. We investigated whether Atractylenolide III (ATL-III), the major component of Atractylodes rhizome can induce apoptosis of the lung carcinoma cells. ATL-III inhibited cell growth, increased lactate dehydrogenase release and modulated cell cycle on human lung carcinoma A549 cells.

Single-particle characterization of indoor aerosol particles collected at an underground shopping area in Seoul, Korea.

Unlabelled: In this study, single-particle characterization of aerosol particles collected at an underground shopping area was performed for the first time. A quantitative single-particle analytical technique, low-Z particle electron probe X-ray microanalysis, was used to characterize a total of 7900 individual particles for eight sets of aerosol samples collected at an underground shopping area in Seoul, Korea. Based on secondary electron images and X-ray spectral data of individual particles, fourteen particle types were identified, in which primary soil-derived particles were the most abundant, followed by carbonaceous, Fe-containing, secondary soil-derived, and secondary sea-salt particles.