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1.
J Am Chem Soc ; 145(16): 8757-8763, 2023 Apr 26.
Artículo en Inglés | MEDLINE | ID: mdl-37042822

RESUMEN

Graphene nanoribbon heterostructures and heterojunctions have attracted interest as next-generation molecular diodes with atomic precision. Their mass production via solution methods and prototypical device integration remains to be explored. Here, the bottom-up solution synthesis and characterization of liquid-phase-processable graphene nanoribbon heterostructures (GNRHs) are demonstrated. Joint photoresponsivity measurements and simulations provide evidence of the structurally defined heterostructure motif acting as a type-I heterojunction. Real-time, time-dependent density functional tight-binding simulations further reveal that the photocurrent polarity can be tuned at different excitation wavelengths. Our results introduce liquid-phase-processable, self-assembled heterojunctions for the development of nanoscale diode circuitry and adaptive hardware.

2.
Sensors (Basel) ; 23(3)2023 Jan 28.
Artículo en Inglés | MEDLINE | ID: mdl-36772478

RESUMEN

Eye-tracking research has allowed the characterisation of gaze behaviours in some racket sports (e.g., tennis, badminton), both in controlled laboratory settings and in real-world scenarios. However, there are no studies about visual patterns displayed by athletes in padel. METHOD: The aim of this exploratory case study was to address the visual behaviours of eight young expert padel athletes when playing match games on a padel court. Specifically, their gaze behaviours were examined with an in situ approach while returned trays/smashes, serves, and volleys were performed by their counterparts. Gaze patterns were registered with an SMI Eye Tracking Glasses 2 Wireless. RESULTS: The participants' gaze was mainly focused on the ball-flight trajectory and on the upper body of the opponents because they were the two visual locations with a larger number of fixations and longer fixation time. No differences were found in these variables for each type of visual location when the three return situations were compared, or independently of them. CONCLUSIONS: Padel players displayed a similar gaze behaviour during different representative return situations. This visual pattern was characterised by fixating at the ball and some opponents' upper kinematics (head, shoulders, trunk, and the region of arm-hand-racket) to perform real interceptive actions while playing against them on a padel court.


Asunto(s)
Deportes de Raqueta , Tenis , Humanos , Desempeño Psicomotor , Atletas , Mano
3.
Nano Lett ; 22(3): 911-917, 2022 Feb 09.
Artículo en Inglés | MEDLINE | ID: mdl-35040646

RESUMEN

Complex van der Waals heterostructures from layered molecular stacks are promising optoelectronic materials offering the means to efficient, modular charge separation and collection layers. The effect of stacking in the electrodynamics of such hybrid organic-inorganic two-dimensional materials remains largely unexplored, whereby molecular scale engineering could lead to advanced optical phenomena. For instance, tunable Fano engineering could make possible on-demand transparent conducting layers or photoactive elements, and passive cooling. We employ an adapted Gersten-Nitzan model and real time time-dependent density functional tight-binding to study the optoelectronics of self-assembled monolayers on graphene nanoribbons. We find Fano resonances that cause electromagnetic induced opacity and transparency and reveal an additional incoherent process leading to interlayer exciton formation with a characteristic charge transfer rate. These results showcase hybrid van der Waals heterostructures as paradigmatic 2D optoelectronic stacks, featuring tunable Fano optics and unconventional charge transfer channels.

4.
Angew Chem Int Ed Engl ; 62(35): e202305737, 2023 Aug 28.
Artículo en Inglés | MEDLINE | ID: mdl-37335764

RESUMEN

The incorporation of nanopores into graphene nanostructures has been demonstrated as an efficient tool in tuning their band gaps and electronic structures. However, precisely embedding the uniform nanopores into graphene nanoribbons (GNRs) at the atomic level remains underdeveloped especially for in-solution synthesis due to the lack of efficient synthetic strategies. Herein we report the first case of solution-synthesized porous GNR (pGNR) with a fully conjugated backbone via the efficient Scholl reaction of tailor-made polyphenylene precursor (P1) bearing pre-installed hexagonal nanopores. The resultant pGNR features periodic subnanometer pores with a uniform diameter of 0.6 nm and an adjacent-pores-distance of 1.7 nm. To solidify our design strategy, two porous model compounds (1 a, 1 b) containing the same pore size as the shortcuts of pGNR, are successfully synthesized. The chemical structure and photophysical properties of pGNR are investigated by various spectroscopic analyses. Notably, the embedded periodic nanopores largely reduce the π-conjugation degree and alleviate the inter-ribbon π-π interactions, compared to the nonporous GNRs with similar widths, affording pGNR with a notably enlarged band gap and enhanced liquid-phase processability.

5.
Subcell Biochem ; 97: 455-482, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33779928

RESUMEN

Preeclampsia (PE) is associated with long-term morbidity in mothers and lifelong morbidities for their children, ranging from cerebral palsy and cognitive delay in preterm infants, to hypertension, diabetes and obesity in adolescents and young adults. There are several processes that are critical for development of materno-fetal exchange, including establishing adequate perfusion of the placenta by maternal blood, and the formation of the placental villous vascular tree. Recent studies provide persuasive evidence that placenta-derived extracellular vesicles (EVs) represent a significant intercellular communication pathway, and that they may play an important role in placental and endothelial cell (both fetal and maternal) function. These functions are known to be altered in PE. EVs can carry and transport a wide range of bioactive molescules that have potential to be used as biomarkers and therapeutic delivery tools for PE. EV content is often parent cell specific, thus providing an insight or "thumbprint" of the intracellular environment of the originating cell (e.g., human placenta). EV have been identified in plasma under both normal and pathological conditions, including PE. The concentration of EVs and their content in plasma has been reported to increase in association with disease severity and/or progression. Placenta-derived EVs have been identified in maternal plasma during normal pregnancy and PE pregnancies. They contain placenta-specific proteins and miRNAs and, as such, may be differentiated from maternally-derived EVs. The aim of this review, thus, is to describe the potential roles of EVs in preecmpatic pregnancies, focussing on EVs secreted from placental cells. The biogenesis, specificity of placental EVs, and methods used to characterise EVs in the context of PE pregnancies will be also discussed.


Asunto(s)
Vesículas Extracelulares , Preeclampsia , Adolescente , Biomarcadores , Niño , Femenino , Humanos , Recién Nacido , Recien Nacido Prematuro , Placenta , Embarazo
6.
J Transl Med ; 19(1): 360, 2021 08 20.
Artículo en Inglés | MEDLINE | ID: mdl-34416903

RESUMEN

BACKGROUND: Gestational diabetes mellitus (GDM) is a serious public health issue affecting 9-15% of all pregnancies worldwide. Recently, it has been suggested that extracellular vesicles (EVs) play a role throughout gestation, including mediating a placental response to hyperglycaemia. Here, we investigated the EV-associated miRNA profile across gestation in GDM, assessed their utility in developing accurate, multivariate classification models, and determined the signaling pathways in skeletal muscle proteome associated with the changes in the EV miRNA profile. METHODS: Discovery: A retrospective, case-control study design was used to identify EV-associated miRNAs that vary across pregnancy and clinical status (i.e. GDM or Normal Glucose Tolerance, NGT). EVs were isolated from maternal plasma obtained at early, mid and late gestation (n = 29) and small RNA sequencing was performed. Validation: A longitudinal study design was used to quantify expression of selected miRNAs. EV miRNAs were quantified by real-time PCR (cases = 8, control = 14, samples at three times during pregnancy) and their individual and combined classification efficiencies were evaluated. Quantitative, data-independent acquisition mass spectrometry was use to establish the protein profile in skeletal muscle biopsies from normal and GDM. RESULTS: A total of 2822 miRNAs were analyzed using a small RNA library, and a total of 563 miRNAs that significantly changed (p < 0.05) across gestation and 101 miRNAs were significantly changed between NGT and GDM. Analysis of the miRNA changes in NGT and GDM separately identified a total of 256 (NGT-group), and 302 (GDM-group) miRNAs that change across gestation. A multivariate classification model was developed, based on the quantitative expression of EV-associated miRNAs, and the accuracy to correctly assign samples was > 90%. We identified a set of proteins in skeletal muscle biopsies from women with GDM associated with JAK-STAT signaling which could be targeted by the miRNA-92a-3p within circulating EVs. Interestingly, overexpression of miRNA-92a-3p in primary skeletal muscle cells increase insulin-stimulated glucose uptake. CONCLUSIONS: During early pregnancy, differently-expressed, EV-associated miRNAs may be of clinical utility in identifying presymptomatic women who will subsequently develop GDM later in gestation. We suggest that miRNA-92a-3p within EVs might be a protected mechanism to increase skeletal muscle insulin sensitivity in GDM.


Asunto(s)
Diabetes Gestacional , Vesículas Extracelulares , MicroARNs , Estudios de Casos y Controles , Diabetes Gestacional/genética , Femenino , Humanos , Quinasas Janus , Estudios Longitudinales , MicroARNs/genética , Placenta , Embarazo , Estudios Retrospectivos , Factores de Transcripción STAT , Transducción de Señal
7.
J Am Chem Soc ; 142(7): 3384-3391, 2020 Feb 19.
Artículo en Inglés | MEDLINE | ID: mdl-32070107

RESUMEN

Vibrational excitations provoked by coupling effects during charge transport through single molecules are intrinsic energy dissipation phenomena, in close analogy to electron-phonon coupling in solids. One fundamental challenge in molecular electronics is the quantitative determination of charge-vibrational (electron-phonon) coupling for single-molecule junctions. The ability to record electron-phonon coupling phenomena at the single-molecule level is a key prerequisite to fully rationalize and optimize charge-transport efficiencies for specific molecular configurations and currents. Here we exemplarily determine the pertaining coupling characteristics for a current-carrying chemically well-defined molecule by synchronous vibrational and current-voltage spectroscopy. These metal-molecule-metal junction insights are complemented by time-resolved infrared spectroscopy to assess the intramolecular vibrational relaxation dynamics. By measuring and analyzing the steady-state vibrational distribution during transient charge transport in a bis-phenylethynyl-anthracene derivative using anti-Stokes Raman scattering, we find ∼0.5 vibrational excitations per elementary charge passing through the metal-molecule-metal junction, by means of a rate model ansatz and quantum-chemical calculations.

8.
J Investig Allergol Clin Immunol ; 30(6): 430-438, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-31530518

RESUMEN

BACKGROUND AND OBJECTIVE: To investigate the quality of life (QOL) of and to characterize patients with atopic dermatitis (AD) in Portugal. METHODS: This was a cross-sectional study of patients with AD and other eczemas. Skindex-29, Skindex-teen, and the Childhood Atopic Dermatitis Impact Scale (CADIS) were the instruments used to assess QOL in adults, teenagers, and children, respectively. The SF-12 was also used, and disease severity was evaluated using the Patient-Oriented SCORAD (PO-SCORAD) instrument. Associations with QOL were assessed based on the odds ratio (OR). P values <.05 and 95%CIs were considered statistically significant. RESULTS: The study population comprised 162 participants aged 0.5-74 years. We found that 37.3% of AD patients consider their disease disabling and that more than half of the patients feel stigmatized by society. The mean Skindex score for AD was 39.68, and the impact on QOL was severe in 44%. "Symptoms" was the most affected category in adults. AD was moderate to severe in 87% of the sample. One of the factors that most influenced poorer QOL in AD was age: with increasing age, the Skindex is likely to increase (OR, 1.03; 95%CI, 1.00-1.06). "Considering the disease a disability" was also associated (OR, 6.72; 95%CI, 2.56-17.63). QOL worsens with increasingly affected body area (OR, 1.07; 95%CI, 1.03-1.11) and the presence of edema (OR, 2.0; 95%CI, 1.23-3.40). CONCLUSIONS: This is the first study to provide data on QOL in patients with AD in Portugal. Our data show an expected negative impact. More awareness-raising activities are needed to increase knowledge, decrease stigmatization, and, consequently, address the factors involved in the QOL of patients with AD.


Asunto(s)
Dermatitis Atópica/epidemiología , Calidad de Vida , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Alérgenos/inmunología , Niño , Costo de Enfermedad , Dermatitis Atópica/diagnóstico , Dermatitis Atópica/etiología , Dermatitis Atópica/terapia , Manejo de la Enfermedad , Susceptibilidad a Enfermedades , Femenino , Humanos , Lactante , Recién Nacido , Masculino , Persona de Mediana Edad , Oportunidad Relativa , Portugal/epidemiología , Vigilancia en Salud Pública , Factores de Riesgo , Índice de Severidad de la Enfermedad , Resultado del Tratamiento , Adulto Joven
9.
J Radiol Prot ; 40(4)2020 Nov 11.
Artículo en Inglés | MEDLINE | ID: mdl-33059345

RESUMEN

The reconstruction of the Cochabamba (Bolivia) radiological incident (IAEA-International Atomic Energy Agency 2004 The Radiological Accident in Cochabamba STI/PUB/1199 (Vienna: IAEA)) was used to assess and evaluate retrospective dosimetry methodologies. For this purpose an unshielded radioactive source was placed inside a transportation vehicle (bus) resembling a radiological exposure device. External doses were assessed using water and anthropomorphic phantoms that were placed at various positions in the vehicle and equipped with both fortuitous dosimeters (chip cards, mobile phones), individual dosimeters (electronic dosimeters, thermoluminescent and optically stimulated luminescence dosimeters) and in three cases also with blood sample tubes in thermos flasks for cytogenetic methods. This paper gives a detailed description of the experimental setup, the results of the reference dosimetry, including organ dose assessment for the phantom closest to the source, and includes a compilation of the main results obtained by the retrospective dosimetry techniques. Comparison is made to the results of dose reconstruction obtained by IAEA during the response to the Cochabamba incident in 2002.


Asunto(s)
Incidentes con Víctimas en Masa , Triaje , Fantasmas de Imagen , Dosis de Radiación , Radiación Ionizante , Radiometría/métodos , Estudios Retrospectivos
10.
J Radiol Prot ; 40(4)2020 Oct 28.
Artículo en Inglés | MEDLINE | ID: mdl-32927439

RESUMEN

During the past 7th Security Framework Program the European Commission funded a research project called CATO (CBRN Crisis management, Architectures, Technologies and Operational procedures) to develop a prototype decision support system for crisis management in addition to providing a suite of guidelines for first responders and incident commanders when dealing with chemical, biological, radiological or nuclear incidents. In order to derive these guidelines a proof-of-concept experiment was setup during which several passive agent (Stable CsCl) dispersions with improvised explosive devices and vehicle-borne improvised explosive devices were carried out. Each dispersion was thoroughly characterised by a number of monitoring devices, including high-volume air samplers and size-segregated air samplers. All environmental and forensic samples were collected by the UK counter terrorism police, following strict labelling and chain-of-custody protocols. The samples were analysed at the Belgian Nuclear Research Center suing the k0 method for instrumental neutron activation technique. A full consequence assessment analysis was carried out assuming that the observed concentration of Cs-133 in samples was Cs-137 instead and use was made of the specific activity of Cs-137. Due to the sensitivity of the information the European Commission classified this research. The resulted reported on in this work have been unclassified and are released to assist emergency planners and first responders to take the necessary precautions. The results indicate that, up to distances of 50 m from ground zero radiation levels will be considerable and therefore live-saving actions must be performed by fire/rescue wearing full protective gear. In addition, low-wind conditions will favor a long airborne residence time and therefore the use of full-face protective gear is a must. In order to protect first responders, a radiation protection specialist is to determine how long people can enter and remain in the contaminated area. The recovery of evidence in the case of a car-bomb will be hard or even impossible due to the high level of radioactive material remaining inside the vehicle.


Asunto(s)
Planificación en Desastres , Socorristas , Protección Radiológica , Liberación de Radiactividad Peligrosa , Terrorismo , Radioisótopos de Cesio , Humanos , Protección Radiológica/métodos , Liberación de Radiactividad Peligrosa/prevención & control
11.
Proteomics ; 19(1-2): e1800164, 2019 01.
Artículo en Inglés | MEDLINE | ID: mdl-30536821

RESUMEN

Several factors including placental hormones (PH) released from the human placenta have been associated with the development of insulin resistance and gestational diabetes mellitus (GDM). However, circulating levels of PH does not correlate well with maternal insulin sensitivity across gestation, suggesting that other, previously unrecognized, mechanisms may be involved. The levels of circulating exosomes are higher in GDM compared to normal. GDM derived exosomes produce greater release of pro-inflammatory cytokines from endothelial cells compared to exosomes from normal, suggesting that their contents may differ compared to normal pregnancies. Using a quantitative, information-independent acquisition (Sequential Windowed Acquisition of All Theoretical Mass Spectra [SWATH]) approach, differentially abundant circulating exosome proteins are identified in women with normal glucose tolerance (NGT) and GDM at the time of GDM diagnosis. A total of 78 statistically significant proteins in the relative expression of exosomal proteins in GDM are compared with NGT. Bioinformatic analysis shows that the exosomal proteins in GDM target pathways are mainly associated with energy production, inflammation, and metabolism. Finally, an independent cohort of patients is used to validate some of the proteins identified by SWATH. The data obtained may be of utility in elucidating the underlying physiological mechanisms associated with insulin resistance in GDM.


Asunto(s)
Diabetes Gestacional/metabolismo , Exosomas/metabolismo , Espectrometría de Masas/métodos , Proteómica/métodos , Biología Computacional , Femenino , Humanos , Embarazo , Transducción de Señal/fisiología
12.
Anal Chem ; 91(6): 3827-3834, 2019 03 19.
Artículo en Inglés | MEDLINE | ID: mdl-30735354

RESUMEN

Most of the current exosome-analysis strategies are time-consuming and largely dependent on commercial extraction kit-based preisolation step, which requires extensive sample manipulations, costly isolation kits, reagents, tedious procedures, and sophisticated equipment and is prone to bias/artifacts. Herein we introduce a simple method for direct isolation and subsequent detection of a specific population of exosomes using an engineered superparamagnetic material with multifunctional properties, namely, gold-loaded ferric oxide nanocubes (Au-NPFe2O3NC). In this method, the Au-NPFe2O3NC were initially functionalized with a generic tetraspanin (exosomes-associated) antibody (i.e., CD63) and dispersed in sample fluids where they work as "dispersible nanocarriers" to capture the bulk population of exosomes. After magnetic collection and purification, Au-NPFe2O3NC-bound exosomes were transferred to the tissue-specific, antibody-modified, screen-printed electrode. As a proof of principle, we used a specific placental marker, placenta alkaline phosphatase (PLAP), to detect exosomes secreted from placental cells. The peroxidase-like activity of Au-NPFe2O3NC was then used to accomplish an enzyme-linked immunosorbent assay (ELISA)-based sensing protocol for naked-eye observation along with UV-visible and electrochemical detection of PLAP-specific exosomes present in placental cell-conditioned media. We demonstrated excellent agreement in analytical performance for the detection of placental cell-derived exosomes (i.e., linear dynamic range, 103-107 exosomes/mL; limit of detection, 103 exosomes/mL; relative standard deviation (%RSD) of <5.5% for n = 3) using with and without commercial "total exosome isolation kit"-based preisolation step. We envisage that this highly sensitive, rapid, and inexpensive assay could be useful in quantifying specific populations of exosomes for various clinical applications, focusing on pregnancy complications.


Asunto(s)
Fosfatasa Alcalina/metabolismo , Técnicas Biosensibles/métodos , Exosomas/metabolismo , Compuestos Férricos/química , Oro/química , Límite de Detección , Nanoporos , Línea Celular Tumoral , Femenino , Humanos , Placenta/enzimología , Embarazo
13.
J Transl Med ; 17(1): 392, 2019 11 27.
Artículo en Inglés | MEDLINE | ID: mdl-31775784

RESUMEN

BACKGROUND: The "nonclassic" apparent mineralocorticoid excess (NC-AME) has been identified in approximately 7% of general population. This phenotype is characterized by low plasma renin activity (PRA), high serum cortisol (F) to cortisone (E) ratio, low cortisone, high Fractional Excretion of potassium (FEK) and normal-elevated systolic blood pressure (SBP). An early detection and/or identification of novel biomarkers of this phenotype could avoid the progression or future complications leading to arterial hypertension. Isolation of extracellular vesicles, such as exosomes, in specific biofluids support the identification of tissue-specific RNA and miRNA, which may be useful as novel biomarkers. Our aim was to identify miRNAs within urinary exosomes associated to the NC-AME phenotype. METHODS: We perform a cross-sectional study in a primary care cohort of 127 Chilean subjects. We measured BP, serum cortisol, cortisone, aldosterone, PRA. According to the previous reported, a subgroup of subjects was classified as NC-AME (n = 10). Urinary exosomes were isolated and miRNA cargo was sequenced by Illumina-NextSeq-500. RESULTS: We found that NC-AME subjects had lower cortisone (p < 0.0001), higher F/E ratio (p < 0.0001), lower serum potassium (p = 0.009) and higher FEK 24 h (p = 0.03) than controls. We found miR-204-5p (fold-change = 0.115; p 0.001) and miR-192-5p (fold-change = 0.246; p 0.03) are both significantly downregulated in NC-AME. miR-192-5p expression was correlated with PRA (r = 0.45; p 0.028) and miR-204-5p expression with SBP (r = - 0.48, p 0.027) and F/E ratio (r = - 0.48; p 0.026). CONCLUSIONS: These findings could support a potential role of these miRNAs as regulators and novel biomarkers of the NC-AME phenotype.


Asunto(s)
Regulación hacia Abajo/genética , Exosomas/genética , MicroARNs/genética , Síndrome de Exceso Aparente de Mineralocorticoides/genética , Adolescente , Adulto , Estudios de Casos y Controles , Niño , Exosomas/ultraestructura , Femenino , Humanos , Masculino , MicroARNs/metabolismo , Persona de Mediana Edad , Síndrome de Exceso Aparente de Mineralocorticoides/orina , Reproducibilidad de los Resultados , Adulto Joven , Síndrome de Exceso Aparente de Mineralocorticoides
14.
Clin Sci (Lond) ; 133(13): 1401-1419, 2019 07 15.
Artículo en Inglés | MEDLINE | ID: mdl-31227603

RESUMEN

Exosomes are small nanovesicles that carry bioactive molecules which can be delivered to neighbouring cells to modify their biological functions. Studies have showed that exosomes from ovarian cancer (OVCA) cells can alter the cell migration and proliferation of cells within the tumour microenvironment, an effect modulated by the invasiveness capacity of their originating cells. Using an OVCA cell line xenograph mouse model, we showed that exosomes derived from a high invasiveness capacity cell line (exo-SKOV-3) promoted metastasis in vivo compared with exosomes from a low invasiveness capacity cell line (exo-OVCAR-3). Analysis from anin vivo imaging system (IVIS) revealed that exo-SKOV-3 formed metastatic niches, whereas exo-OVCAR-3 formed colonies of clustered cells close to the site of injection. Interestingly, kinetic parameters showed that the half-maximal stimulatory time (ST50) of tumour growth with exo-OVCAR-3 (4.0 ± 0.31 weeks) was significantly lower compared with the ST50 in mice injected with exo-SKOV-3 (4.5 ± 0.32 weeks). However, the number of metastic nodes in mice injected with exo-SKOV-3 was higher compared with exo-OVCAR-3. Using a quantitative mass spectrometry approach (SWATH MS/MS) followed by bioinformatics analysis using the Ingenuity Pathway Analysis (IPA), we identified a total of 771 proteins. Furthermore, 40 of these proteins were differentially expressed in tumour tissues from mice injected with exo-SKOV-3 compared with exo-OVCAR-3, and associated with Wnt canonical pathway (ß-catenin). Finally, we identified a set of proteins which had elevated expression in the circulating exosomes in association with tumour metastasis. These observations suggest that exosomal signalling plays an important role in OVCA metastasis.


Asunto(s)
Movimiento Celular , Exosomas/patología , Neoplasias Ováricas/patología , Neoplasias Peritoneales/secundario , Animales , Línea Celular Tumoral , Proliferación Celular , Exosomas/metabolismo , Exosomas/trasplante , Femenino , Humanos , Ratones Endogámicos NOD , Invasividad Neoplásica , Metástasis de la Neoplasia , Proteínas de Neoplasias/metabolismo , Neoplasias Ováricas/metabolismo , Neoplasias Peritoneales/metabolismo , Mapas de Interacción de Proteínas , Factores de Tiempo , Carga Tumoral , Microambiente Tumoral , Vía de Señalización Wnt
15.
Angew Chem Int Ed Engl ; 58(33): 11285-11290, 2019 08 12.
Artículo en Inglés | MEDLINE | ID: mdl-31120567

RESUMEN

Reaction pathways involving quantum tunneling of protons are fundamental to chemistry and biology. They are responsible for essential aspects of interstellar synthesis, the degradation and isomerization of compounds, enzymatic activity, and protein dynamics. On-surface conditions have been demonstrated to open alternative routes for organic synthesis, often with intricate transformations not accessible in solution. Here, we investigate a hydroalkoxylation reaction of a molecular species adsorbed on a Ag(111) surface by scanning tunneling microscopy complemented by X-ray electron spectroscopy and density functional theory. The closure of the furan ring proceeds at low temperature (down to 150 K) and without detectable side reactions. We unravel a proton-tunneling-mediated pathway theoretically and confirm experimentally its dominant contribution through the kinetic isotope effect with the deuterated derivative.

16.
J Am Chem Soc ; 140(14): 4835-4840, 2018 04 11.
Artículo en Inglés | MEDLINE | ID: mdl-29565575

RESUMEN

Precisely controlling well-defined, stable single-molecule junctions represents a pillar of single-molecule electronics. Early attempts to establish computing with molecular switching arrays were partly challenged by limitations in the direct chemical characterization of metal-molecule-metal junctions. While cryogenic scanning probe studies have advanced the mechanistic understanding of current- and voltage-induced conformational switching, metal-molecule-metal conformations are still largely inferred from indirect evidence. Hence, the development of robust, chemically sensitive techniques is instrumental for advancement in the field. Here we probe the conformation of a two-state molecular switch with vibrational spectroscopy, while simultaneously operating it by means of the applied voltage. Our study emphasizes measurements of single-molecule Raman spectra in a room-temperature stable single-molecule switch presenting a signal modulation of nearly 2 orders of magnitude.

17.
J Am Chem Soc ; 140(25): 7803-7809, 2018 06 27.
Artículo en Inglés | MEDLINE | ID: mdl-29779378

RESUMEN

Among organic electronic materials, graphene nanoribbons (GNRs) offer extraordinary versatility as next-generation semiconducting materials for nanoelectronics and optoelectronics due to their tunable properties, including charge-carrier mobility, optical absorption, and electronic bandgap, which are uniquely defined by their chemical structures. Although planar GNRs have been predominantly considered until now, nonplanarity can be an additional parameter to modulate their properties without changing the aromatic core. Herein, we report theoretical and experimental studies on two GNR structures with "cove"-type edges, having an identical aromatic core but with alkyl side chains at different peripheral positions. The theoretical results indicate that installment of alkyl chains at the innermost positions of the "cove"-type edges can "bend" the peripheral rings of the GNR through steric repulsion between aromatic protons and the introduced alkyl chains. This structural distortion is theoretically predicted to reduce the bandgap by up to 0.27 eV, which is corroborated by experimental comparison of thus synthesized planar and nonplanar GNRs through UV-vis-near-infrared absorption and photoluminescence excitation spectroscopy. Our results extend the possibility of engineering GNR properties, adding subtle structural distortion as a distinct and potentially highly versatile parameter.

18.
Clin Sci (Lond) ; 132(18): 2029-2044, 2018 09 28.
Artículo en Inglés | MEDLINE | ID: mdl-30219799

RESUMEN

Ovarian cancer has resulted in over 140 000 deaths reported annually worldwide. This is often attributed to cellular changes in the microenvironment, including increased migration of mesenchymal stem cells (MSCs) and endothelial cells (ECs) to facilitate metastasis. Recently, the ability of exosomes to communicate signals between cells (and promote cancer progression) has been established. In the present study, we explored the effect of exosomes on cells present in the tumour microenvironment. Exosomes were isolated from ovarian cancer cells with different invasive capacity (high = SKOV-3 and low = OVCAR-3) by differential and buoyant density centrifugation and characterised using nanoparticle tracking analysis (NTA), Western blot, and EM. Exosome secretion was positively correlated with invasiveness of releasing cells. Proteomic analyses identified common and unique proteins between exosomes from SKOV-3 and OVCAR-3 with gene ontology analyses revealing that these exosomes are involved in the regulation of cell migration. Since the tumour microenvironment contains multiple cell types, including MSCs and ECs, we examined the effect of these exosomes on MSC and EC migration. Exosomes promoted MSC and EC migration in a time- and concentration-dependent manner. The effect of exosomes isolated from SKOV-3 on cell migration was significantly higher compared with exosomes from OVCAR-3. Thus, we suggest that exosomes from ovarian cancer cells contain a specific set of proteins that are representative of its cell of origin and the invasive capacity.


Asunto(s)
Células Endoteliales/metabolismo , Exosomas/metabolismo , Células Madre Mesenquimatosas/metabolismo , Proteómica/métodos , Comunicación Celular/genética , Línea Celular Tumoral , Movimiento Celular/genética , Proliferación Celular/genética , Exosomas/genética , Femenino , Humanos , Neoplasias Ováricas/genética , Neoplasias Ováricas/metabolismo , Neoplasias Ováricas/patología , Microambiente Tumoral/genética
19.
Clin Sci (Lond) ; 132(22): 2451-2467, 2018 11 30.
Artículo en Inglés | MEDLINE | ID: mdl-30254065

RESUMEN

There is increasing evidence that miRNAs, which are enriched in nanovesicles called exosomes, are important regulators of gene expression. When compared with normal pregnancies, pregnancies with gestational diabetes mellitus (GDM) are associated with skeletal muscle insulin resistance as well as increased levels of circulating placental exosomes. Here we investigated whether placental exosomes in GDM carry a specific set of miRNAs associated with skeletal muscle insulin sensitivity. Exosomes were isolated from chorionic villous (CV) explants from both women with Normal Glucose Tolerant (NGT) and GDM pregnancies. Using miRNA sequencing, we identified a specific set of miRNAs selectively enriched with exosomes and compared with their cells of origin indicating a specific packaging of miRNAs into exosomes. Gene target and ontology analysis of miRNA differentially expressed in exosomes secreted in GDM compared with NGT are associated with pathways regulating cell migration and carbohydrate metabolism. We determined the expression of a selected set of miRNAs in placenta, plasma, and skeletal muscle biopsies from NGT and GDM. Interestingly, the expression of these miRNAs varied in a consistent pattern in the placenta, in circulating exosomes, and in skeletal muscle in GDM. Placental exosomes from GDM pregnancies decreased insulin-stimulated migration and glucose uptake in primary skeletal muscle cells obtained from patients with normal insulin sensitivity. Interestingly, placental exosomes from NGT increase migration and glucose uptake in response to insulin in skeletal muscle from diabetic subjects. These findings suggest that placental exosomes might have a role in the changes on insulin sensitivity in normal and GDM pregnancies.


Asunto(s)
Vellosidades Coriónicas/metabolismo , Diabetes Gestacional/genética , Exosomas/genética , Hipoglucemiantes/farmacología , Resistencia a la Insulina/genética , Insulina/farmacología , MicroARNs/metabolismo , Mioblastos Esqueléticos/efectos de los fármacos , Transcriptoma , Adulto , Estudios de Casos y Controles , Movimiento Celular/efectos de los fármacos , Células Cultivadas , Diabetes Gestacional/diagnóstico , Diabetes Gestacional/metabolismo , Exosomas/metabolismo , Femenino , Glucosa/metabolismo , Humanos , MicroARNs/genética , Mioblastos Esqueléticos/metabolismo , Embarazo , Adulto Joven
20.
Angew Chem Int Ed Engl ; 56(27): 7797-7802, 2017 06 26.
Artículo en Inglés | MEDLINE | ID: mdl-28481441

RESUMEN

The aggregation of (pro)chiral/achiral molecules into crystalline structures at interfaces forms conglomerates, racemates, and solid solutions, comparable to known bulk phases. Scanning tunneling microscopy and Monte Carlo simulations were employed to uncover a distinct racemic phase, expressing 1D disordered chiral sorting through random tiling in surface-confined supramolecularly assembled achiral 4,4''-diethynyl-1,1':4',1''-terphenyl molecules. The configurational entropy of the 1D disordered racemic tiling phase was verified by analytical modeling, and found to lie between that of a perfectly ordered 2D racemate and a racemic solid solution.

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