Highly emissive blue graphene quantum dots with excitation-independent emission via ultrafast liquid-phase photoreduction.

Graphene oxide quantum dots (GOQDs) are promising candidates for biomedical applications since they have lower toxicity and higher biocompatibility than traditional semiconductor quantum dots. However, oxygen functional groups such as epoxy and hydroxyl groups usually induce nonradiative relaxation, which leads to GOQDs exhibiting nonemissive properties. For the enhancement of the emission efficiency of GOQDs, the number of nonradiative relaxation sites should be reduced. This paper reports the synthesis of highly luminescent reduced GOQDs prepared by liquid-phase photoreduction (LPP-rGOQDs). First, GOQDs was fabricated from single-walled carbon nanotubes through chlorate-based oxidation and separation after acoustic cavitation. Subsequently, LPP-rGOQDs were obtained by liquid-phase photoreduction of the GOQD suspension under intense pulsed light irradiation. Liquid-phase photoreduction selectively reduced epoxy groups present on the basal plane of GOQDs, and hydrogenated the basal plane without removal of carbonyl and carboxyl groups at the edges of the GOQDs. Such selective removal of oxidative functional groups was used to control the reduction degree of GOQDs, closely related to their optical properties. The optimized LPP-rGOQDs were bright blue in color and showed quantum yields up to about 19.7%, which was 10 times the quantum yield of GOQDs. Furthermore, the LPP-rGOQDs were utilized to image a human embryonic kidney (HEK293A), and a low cytotoxicity level and satisfactory cell imaging performance were observed.

Cyclic Stretch Promotes Cellular Reprogramming Process through Cytoskeletal-Nuclear Mechano-Coupling and Epigenetic Modification.

Advancing the technologies for cellular reprogramming with high efficiency has significant impact on regenerative therapy, disease modeling, and drug discovery. Biophysical cues can tune the cell fate, yet the precise role of external physical forces during reprogramming remains elusive. Here the authors show that temporal cyclic-stretching of fibroblasts significantly enhances the efficiency of induced pluripotent stem cell (iPSC) production. Generated iPSCs are proven to express pluripotency markers and exhibit in vivo functionality. Bulk RNA-sequencing reveales that cyclic-stretching enhances biological characteristics required for pluripotency acquisition, including increased cell division and mesenchymal-epithelial transition. Of note, cyclic-stretching activates key mechanosensitive molecules (integrins, perinuclear actins, nesprin-2, and YAP), across the cytoskeletal-to-nuclear space. Furthermore, stretch-mediated cytoskeletal-nuclear mechano-coupling leads to altered epigenetic modifications, mainly downregulation in H3K9 methylation, and its global gene occupancy change, as revealed by genome-wide ChIP-sequencing and pharmacological inhibition tests. Single cell RNA-sequencing further identifies subcluster of mechano-responsive iPSCs and key epigenetic modifier in stretched cells. Collectively, cyclic-stretching activates iPSC reprogramming through mechanotransduction process and epigenetic changes accompanied by altered occupancy of mechanosensitive genes. This study highlights the strong link between external physical forces with subsequent mechanotransduction process and the epigenetic changes with expression of related genes in cellular reprogramming, holding substantial implications in the field of cell biology, tissue engineering, and regenerative medicine.

TAUCON and TAUCOM: A novel biosensor based on fluorescence resonance energy transfer for detecting tau hyperphosphorylation-associated cellular pathologies.

Tauopathies are neurodegenerative diseases characterized by abnormal conformational changes in tau protein. Early hyperphosphorylation-induced conformational changes are considered a hallmark of tauopathy, but real-time tracking methods are lacking. Here, we present two novel fluorescence resonance energy transfer (FRET)-based tau biosensors that detect such changes with high spatiotemporal resolution at the single-cell level. The TAUCON biosensor measures instantaneous conformational changes in hyperphosphorylated tau within 20 min, while the TAUCOM biosensor detects changes in the paper-clip structure of microtubule-associated tau. Our biosensors provide faster and more precise detection than conventional methods and can serve as valuable tools for investigating the initial causes, mechanisms, progression, and treatment of tauopathies.

A haem-sequestering plant peptide promotes iron uptake in symbiotic bacteria.

Symbiotic partnerships with rhizobial bacteria enable legumes to grow without nitrogen fertilizer because rhizobia convert atmospheric nitrogen gas into ammonia via nitrogenase. After Sinorhizobium meliloti penetrate the root nodules that they have elicited in Medicago truncatula, the plant produces a family of about 700 nodule cysteine-rich (NCR) peptides that guide the differentiation of endocytosed bacteria into nitrogen-fixing bacteroids. The sequences of the NCR peptides are related to the defensin class of antimicrobial peptides, but have been adapted to play symbiotic roles. Using a variety of spectroscopic, biophysical and biochemical techniques, we show here that the most extensively characterized NCR peptide, 24 amino acid NCR247, binds haem with nanomolar affinity. Bound haem molecules and their iron are initially made biologically inaccessible through the formation of hexamers (6 haem/6 NCR247) and then higher-order complexes. We present evidence that NCR247 is crucial for effective nitrogen-fixing symbiosis. We propose that by sequestering haem and its bound iron, NCR247 creates a physiological state of haem deprivation. This in turn induces an iron-starvation response in rhizobia that results in iron import, which itself is required for nitrogenase activity. Using the same methods as for L-NCR247, we show that the D-enantiomer of NCR247 can bind and sequester haem in an equivalent manner. The special abilities of NCR247 and its D-enantiomer to sequester haem suggest a broad range of potential applications related to human health.

Förster Resonance Energy Transfer-Based Single-Cell Imaging Reveals Piezo1-Induced Ca2+ Flux Mediates Membrane Ruffling and Cell Survival.

A mechanosensitive ion channel, Piezo1 induces non-selective cation flux in response to various mechanical stresses. However, the biological interpretation and underlying mechanisms of cells resulting from Piezo1 activation remain elusive. This study elucidates Piezo1-mediated Ca2+ influx driven by channel activation and cellular behavior using novel Förster Resonance Energy Transfer (FRET)-based biosensors and single-cell imaging analysis. Results reveal that extracellular Ca2+ influx via Piezo1 requires intact caveolin, cholesterol, and cytoskeletal support. Increased cytoplasmic Ca2+ levels enhance PKA, ERK, Rac1, and ROCK activity, which have the potential to promote cancer cell survival and migration. Furthermore, we demonstrate that Piezo1-mediated Ca2+ influx upregulates membrane ruffling, a characteristic feature of cancer cell metastasis, using spatiotemporal image correlation spectroscopy. Thus, our findings provide new insights into the function of Piezo1, suggesting that Piezo1 plays a significant role in the behavior of cancer cells.

Anatomical Classification for Plantaris Tendon Insertion and Its Clinical Implications: A Cadaveric Study.

The purposes of this study were to ascertain the morphological characteristics of a plantaris tendon (PT) insertion using a larger-scale dissection of Korean cadavers and to classify the types of PT insertion related to the calcaneal tendon (CT). A total of 108 feet from adult formalin-fixed cadavers (34 males, 20 females) were dissected. The morphological characteristics and measurements of the PT insertion were evaluated. Five types of PT insertion were classified, wherein the most common type was Type 1 (39 feet, 63.1%). Type 2 and Type 3 were similar, with 16 feet (14.8%) and 15 feet (13.9%), respectively. Type 4 (6 feet, 5.6%) was the rarest type, and Type 5 had 25 feet (23.1%). The case of an absent PT was noted in 7 feet (6.5%). In the proximal portion, the tendon had a thick and narrow shape, became thin and wide in the middle portion, and then changed to thick and narrow again just before the insertion into the calcaneal tuberosity. This study confirmed the five types according to the location of the PT and the area of its insertion-related CT. The morphology of the PT insertion may be anatomically likely to influence the occurrence of tendinopathy in the CT.

Rhynchosia volubilis Promotes Cell Survival via cAMP-PKA/ERK-CREB Pathway.

Rhynchosia volubilis, a small black bean, has been used as a traditional remedy to treat diseases and maintain health in East Asia, but its cellular effects and molecular mechanisms are not fully understood. The purpose of this study was to investigate the effect of ethanol extract from Rhynchosia volubilis (EERV) on cell survival and to elucidate the biochemical signaling pathways. Our results showed that EERV stimulated the cyclic AMP (cAMP) signal revealed by a fluorescent protein (FP)-based intensiometric sensor. Using a Förster resonance energy transfer (FRET)-based sensor, we further revealed that EERV could activate PKA and ERK signals, which are downstream effectors of cAMP. In addition, we reported that EERV could induce the phosphorylation of CREB, a key signal for cell survival. Thus, our results suggested that EERV protects against apoptosis by activating the cell survival pathway through the cAMP-PKA/ERK-CREB pathway.

Distinct calcium regulation of TRPM7 mechanosensitive channels at plasma membrane microdomains visualized by FRET-based single cell imaging.

Transient receptor potential subfamily M member 7 (TRPM7), a mechanosensitive Ca2+ channel, plays a crucial role in intracellular Ca2+ homeostasis. However, it is currently unclear how cell mechanical cues control TRPM7 activity and its associated Ca2+ influx at plasma membrane microdomains. Using two different types of Ca2+ biosensors (Lyn-D3cpv and Kras-D3cpv) based on fluorescence resonance energy transfer, we investigate how Ca2+ influx generated by the TRPM7-specific agonist naltriben is mediated at the detergent-resistant membrane (DRM) and non-DRM regions. This study reveals that TRPM7-induced Ca2+ influx mainly occurs at the DRM, and chemically induced mechanical perturbations in the cell mechanosensitive apparatus substantially reduce Ca2+ influx through TRPM7, preferably located at the DRM. Such perturbations include the disintegration of lipid rafts, microtubules, or actomyosin filaments; the alteration of actomyosin contractility; and the inhibition of focal adhesion and Src kinases. These results suggest that the mechanical membrane environment contributes to the TRPM7 function and activity. Thus, this study provides a fundamental understanding of how the mechanical aspects of the cell membrane regulate the function of mechanosensitive channels.

Anti-cancer potential of persimmon (Diospyros kaki) leaves via the PDGFR-Rac-JNK pathway.

Persimmon leaves are known to have some beneficial effects, including ROS elimination, lipid circulation, and neuronal protection. However, their anti-cancer properties and the underlying mechanisms remain unclear. Herein, we show that treatment with the ethanol extract of persimmon, Diospyros kaki, leaves (EEDK) induces cancer cell death and inhibits cell proliferation. Using fluorescence resonance energy transfer (FRET) technology with genetically-encoded biosensors, we first found that EEDK stimulates a PDGFR-Rac signaling cascade in live cells. Moreover, we found that downstream of the PDGFR-Rac pathway, JNKs are activated by EEDK. In contrast, JNK-downstream inhibitors, such as CoCl2, T-5224, and pepstatin A, attenuated EEDK-induced cell death. Thus, we illustrate that the PDGFR-Rac-JNK signaling axis is triggered by EEDK, leading to cancer cell death, suggesting the extract of persimmon leaves may be a promising anti-cancer agent.

Microcellular Environmental Regulation of Silver Nanoparticles in Cancer Therapy: A Critical Review.

Silver nanoparticles (AgNPs) play significant roles in various cancer cells such as functional heterogeneity, microenvironmental differences, and reversible changes in cell properties (e.g., chemotherapy). There is a lack of targets for processes involved in tumor cellular heterogeneity, such as metabolic clampdown, cytotoxicity, and genotoxicity, which hinders microenvironmental biology. Proteogenomics and chemical metabolomics are important tools that can be used to study proteins/genes and metabolites in cells, respectively. Chemical metabolomics have many advantages over genomics, transcriptomics, and proteomics in anticancer therapy. However, recent studies with AgNPs have revealed considerable genomic and proteomic changes, particularly in genes involved in tumor suppression, apoptosis, and oxidative stress. Metabolites interact biochemically with energy storage, neurotransmitters, and antioxidant defense systems. Mechanobiological studies of AgNPs in cancer metabolomics suggest that AgNPs may be promising tools that can be exploited to develop more robust and effective adaptive anticancer therapies. Herein, we present a proof-of-concept review for AgNPs-based proteogenomics and chemical metabolomics from various tumor cells with the help of several technologies, suggesting their promising use as drug carriers for cancer therapy.

Matrix Rigidity-Dependent Regulation of Ca2+ at Plasma Membrane Microdomains by FAK Visualized by Fluorescence Resonance Energy Transfer.

The dynamic regulation of signal transduction at plasma membrane microdomains remains poorly understood due to limitations in current experimental approaches. Genetically encoded biosensors based on fluorescent resonance energy transfer (FRET) can provide high spatiotemporal resolution for imaging cell signaling networks. Here, distinctive regulation of focal adhesion kinase (FAK) and Ca2+ signals are visualized at different membrane microdomains by FRET using membrane-targeting biosensors. It is shown that rigidity-dependent FAK and Ca2+ signals in human mesenchymal stem cells (hMSCs) are selectively activated at detergent-resistant membrane (DRM or rafts) microdomains during the cell-matrix adhesion process, with minimal activities at non-DRM domains. The rigidity-dependent Ca2+ signal at the DRM microdomains is downregulated by either FAK inhibition or lipid raft disruption, suggesting that FAK and lipid raft integrity mediate the in situ Ca2+ activation. It is further revealed that transient receptor potential subfamily M7 (TRPM7) participates in the mobilization of Ca2+ signals within DRM regions. Thus, the findings provide insights into the underlying mechanisms that regulate Ca2+ and FAK signals in hMSCs under different mechanical microenvironments.

Ectopic Expression of SjCBL1, Calcineurin B-Like 1 Gene From Sedirea japonica, Rescues the Salt and Osmotic Stress Hypersensitivity in Arabidopsis cbl1 Mutant.

Extensive studies with Arabidopsis thaliana suggested that calcineurin B-like (CBL) proteins constitute a unique family of calcium sensors in plants, which mediate a variety of abiotic stress responses. However, little is known about their function in most plants that do not have available genome sequences. In this study, we have developed a pair of universal primers that make it possible to isolate CBL1-like genes from various plants without sequence information. Using these primers, we successfully cloned a full-length cDNA of CBL1-like gene in Sedirea japonica (SjCBL1). Bimolecular fluorescence complementation (BiFC) and pull-down assays demonstrated that like Arabidopsis CBL1 (AtCBL1), SjCBL1 can interacts physically with Arabidopsis CBL-interacting protein kinase 1 (AtCIPK1) at the plasma membrane of plant cells in a Ca2+-dependent manner. In addition, overexpression of SjCBL1 in the Arabidopsis cbl1 mutant resulted in not only rescuing the hypersensitive phenotype toward salt and osmotic stresses, but also substantially enhancing the tolerance to them. Taken together, these results strongly suggest that SjCBL1 is a functional ortholog of AtCBL1 in Sedirea japonica, which can play a critical role in response to salt and osmotic stresses. Therefore, it is clear that our findings should significantly contribute to broadening and deepening our understanding of the CBL1-mediated Ca2+ signaling networks in the plant kingdom.

Ultra Gas-Proof Polymer Hybrid Thin Layer.

Hermetic sealing is an important technology for isolating and protecting air-sensitive materials and is key in the development of foldable and stretchable electronic devices. Here we report an ultra gas-proof polymer hybrid thin layer prepared by filling the free volume of the polymer with Al2O3 using gas-phase atomic layer infiltration. The high-density polymer-inorganic hybrid shows extremely low gas transmission rate, below the detection limit of the Ca corrosion test (water vapor transmission rate <10-7 g m-2 day-1). Furthermore, because of the remarkable nanometer-scale thinness of the complete polymer-inorganic hybrid, it is highly flexible, which makes it useful for hermetic sealing of stretchable and foldable devices.

Extremely High Barrier Performance of Organic-Inorganic Nanolaminated Thin Films for Organic Light-Emitting Diodes.

This work presents a novel barrier thin film based on an organic-inorganic nanolaminate, which consists of alternating nanolayers of self-assembled organic layers (SAOLs) and Al2O3. The SAOLs-Al2O3 nanolaminated films were deposited using a combination of molecular layer deposition and atomic layer deposition techniques at 80 °C. Modulation of the relative thickness ratio of the SAOLs and Al2O3 enabled control over the elastic modulus and stress in the films. Furthermore, the SAOLs-Al2O3 thin film achieved a high degree of mechanical flexibility, excellent transmittance (>95%), and an ultralow water-vapor transmission rate (2.99 × 10-7 g m-2 day-1), which represents one of the lowest permeability levels ever achieved by thin film encapsulation. On the basis of its outstanding barrier properties with high flexibility and transparency, the nanolaminated film was applied to a commercial OLEDs panel as a gas-diffusion barrier film. The results showed defect propagation could be significantly inhibited by incorporating the SAOLs layers, which enhanced the durability of the panel.

Electrical, Optical, and Thermal Behaviors of Transparent Film Heater Made of Reduced Graphene Oxide.

The electrical conductivity and the thermal performance of the films made of reduced graphene oxide (rGO) spray-coated on polycarbonate substrate were investigated. The electrical conductivity and the transmittance of 10 times spray coated film made from the solution with 0.08 wt% of rGO, 0.16 wt% of surfactant were 30 komega/sq and 64%, respectively. The steady-state temperature of the films increased from 25 degrees C for 40 komega/sq to 100 degrees C for 490 omega/sq at an applied voltage of 110 V. The heat transfer coefficient of the rGO coated film, a, was obtained as 139 W/m2 K using the model equation based on the thermal balance, which includes Joule heating convectional, and radiative heat transfers. The transmittance of the films decreased continuously from 73% with the increase of surface resistivity.

The Relationship between Neck Pain and Cervical Alignment in Young Female Nursing Staff.

OBJECTIVE: Degenerative changes in the cervical spine are commonly accompanied by cervical kyphosis which can cause neck pain. This study examined the relationship between neck pain and cervical alignment. METHODS: A total of 323 female nursing staff from our hospital were enrolled. Sagittal radiographs of the cervical spine, Body Mass Index (BMI), Visual Analogue Scale (VAS) measures of neck and arm pain, Neck Disability Index (NDI) and the Short Form (36) Health Survey (SF-36 scores) were obtained and reviewed retrospectively. Global lordosis (GL) of the cervical spine was measured on radiograph images. Correlations between GL and questionnaire scores were investigated using the following three methods : 1) correlation between GL and questionnaire scores among the entire sample; 2) subgroup analysis of patients with "kyphosis (KYP) : GL scores<0" vs. those with "lordosis (LOR) : GL scores>0" on questionnaire measures; and 3) subgroup analysis of patients with pain vs. those without pain, on GL and questionnaire measures. RESULTS: There was no significant correlation between GL and any questionnaire measure. There was a significant difference between the mean GLs of the KYP and LOR groups, but there were no group differences in BMI, age or any questionnaire measures. There was no difference between the pain (n=92) and pain-free (n=231) groups in age, BMI or GL, but there were differences in neck, and arm pain, and physical function and NDI scores. CONCLUSIONS: Our data suggest that kyphotic deformity was not associated with neck pain.

Development and evaluation of a dynamic multimedia model (ECORAME) for local scale assessment of aquatic ecological exposure to chemicals originating from sources in environmental media.

Use of multimedia models (MMMs) has been limited in exposure assessment for aquatic ecosystems at local scale typically due to their coarse spatial resolution and inability to predict the individual concentrations of multiple streams within a watershed cell. An MMM named ECORAME is presented which overcomes the limitations by treating each water segment as an independent cell rather than a compartment within a watershed cell. This offers two advantages for exposure assessment, i.e., i) the spatial resolution for water is readily adjustable and ii) multiple water streams within one watershed cell could be handled individually. Model evaluation with respect to polycyclic aromatic hydrocarbons (PAHs) demonstrated that ECORAME's prediction of relative concentration agreed with measured values within a factor of five or less. A case study of PAHs using ECORAME shows that the concentration can change by more than 10 fold over the 40km main stream stretch of the Han River in Seoul, Korea. The concentration difference among multiple streams in the same watershed cell could be substantial (greater than 100 fold). Besides a need of finer spatial resolutons than those typically used in MMMs, the results strongly suggest that exposure prediction capability for individual streams in the same watershed is necessary for local scale assessment. As demostrated with ECORAME, the need can be effectively met by handling the water segments as individual cells in future MMMs.

Stability-improved organic n-channel thin-film transistors with nm-thin hydrophobic polymer-coated high-k dielectrics.

We report on the fabrication of N,N'-ditridecyl-perylene-3,4:9,10-tetracarboxylic diimide-C13 (PTCDI-C13), n-channel organic thin-film transistors (OTFTs) with 30 nm Al(2)O(3) whose surface has been un-modified or modified with hexamethyldisilazane (HMDS) and thin hydrophobic CYTOP. Among all the devices, the OTFTs with CYTOP-modified dielectrics exhibit the most superior device performance and stability. The optimum post-annealing temperature for organic n-channels on CYTOP was also found to be as low as 80 °C, although the post-annealing was previously implemented at 120-140 °C for PTCDI domain growth in general. The low temperature of 80 °C hardly damages the CYTOP/n-channel organic interface which is deformed at a temperature higher than the glass transition temperature of CYTOP (∼110 °C). The pentacenequinone passivation layer turned out to be helpful to keep the interfacial trap density minimum, according to the photo-excited charge collection spectroscopy results for our 80 °C-annealed OTFTs with CYTOP-modified dielectrics.

Value of adrenal venous sampling for lesion localization in primary aldosteronism.

BACKGROUND: Distinguishing between unilateral and bilateral adrenal lesions is mandatory for surgical treatment of primary aldosteronism (PA). Adrenal venous sampling (AVS) is considered the gold standard for identification and localization of the lesion or lesions causing PA. The objective of the present study was to determine the usefulness of AVS in PA patients. PATIENTS AND METHODS: From January 2001 to October 2011, 86 patients with the biochemical diagnosis of PA were retrospectively analyzed. The study group included 45 males and 41 females with a mean age of 50.7 ± 12.6 years, and all patients underwent adrenal computed tomography (CT) and AVS. RESULTS: The catheterization success rate of AVS was 82.69 % (86/104). In addition, AVS revealed bilateral lesions in 15/75 patients with unilateral abnormalities diagnosed by CT. These patients underwent medical treatment instead of surgery. One patient had an adrenal mass on the right side, but AVS localized the lesion on the left side. This patient underwent left adrenalectomy. Furthermore, AVS revealed a unilateral lesion in 2/5 patients with bilateral abnormalities demonstrated by CT. These patients underwent unilateral adrenalectomy. Finally, AVS demonstrated localization in 1/6 of patients with no CT abnormalities who were subjected to surgery. Fifty-three patients with unilateral lesion and one patient with bilateral hypersecretion underwent surgical removal of the affected gland(s). All patients had resolution of hypokalemia and clinical improvement of hypertension. CONCLUSIONS: Many patients (19/86, or 22.09 %) would have been inappropriately managed if decision making had been based solely on CT findings. Therefore, AVS is recommended before determining definitive PA management.

Fabrication of a new type of organic-inorganic hybrid superlattice films combined with titanium oxide and polydiacetylene.

We fabricated a new organic-inorganic hybrid superlattice film using molecular layer deposition [MLD] combined with atomic layer deposition [ALD]. In the molecular layer deposition process, polydiacetylene [PDA] layers were grown by repeated sequential adsorption of titanium tetrachloride and 2,4-hexadiyne-1,6-diol with ultraviolet polymerization under a substrate temperature of 100°C. Titanium oxide [TiO2] inorganic layers were deposited at the same temperatures with alternating surface-saturating reactions of titanium tetrachloride and water. Ellipsometry analysis showed a self-limiting surface reaction process and linear growth of the nanohybrid films. The transmission electron microscopy analysis of the titanium oxide cross-linked polydiacetylene [TiOPDA]-TiO2 thin films confirmed the MLD growth rate and showed that the films are amorphous superlattices. Composition and polymerization of the films were confirmed by infrared spectroscopy. The TiOPDA-TiO2 nanohybrid superlattice films exhibited good thermal and mechanical stabilities.PACS: 81.07.Pr, organic-inorganic hybrid nanostructures; 82.35.-x, polymerization; 81.15.-z, film deposition; 81.15.Gh, chemical vapor deposition (including plasma enhanced CVD, MOCVD, ALD, etc.).