Conductivity in organic semiconductors hybridized with the vacuum field

Organic semiconductors have generated considerable interest for their potential for creating inexpensive and flexible devices easily processed on a large scale [1-11]. However technological applications are currently limited by the low mobility of the charge carriers associated with the disorder in these materials [5-8]. Much effort over the past decades has therefore been focused on optimizing the organisation of the material or the devices to improve carrier mobility. Here we take a radically different path to solving this problem, namely by injecting carriers into states that are hybridized to the vacuum electromagnetic field. These are coherent states that can extend over as many as 10^5 molecules and should thereby favour conductivity in such materials. To test this idea, organic semiconductors were strongly coupled to the vacuum electromagnetic field on plasmonic structures to form polaritonic states with large Rabi splittings ca. 0.7 eV. Conductivity experiments show that indeed the current does increase by an order of magnitude at resonance in the coupled state, reflecting mostly a change in field-effect mobility as revealed when the structure is gated in a transistor configuration. A theoretical quantum model is presented that confirms the delocalization of the wave-functions of the hybridized states and the consequences on the conductivity. While this is a proof-of-principle study, in practice conductivity mediated by light-matter hybridized states is easy to implement and we therefore expect that it will be used to improve organic devices. More broadly our findings illustrate the potential of engineering the vacuum electromagnetic environment to modify and to improve properties of materials.Comment: 16 pages, 13 figure

New in vitro approaches to evaluate antioxidant activity of food and their application to real samples

Several epidemiological studies have shown that the production of reactive oxygen species (ROS) contributes to the risk factors for chronic pathological conditions, such as cardiovascular diseases, cancer and diabetes [1]. A diet that includes foods rich in antioxidant compounds, in combination with a correct lifestyle, represents a possible approach to counteract the negative effects of the oxidative stress. On these bases, several studies have been focused on the determination of antioxidant properties of food; the methods used to assess the antioxidant activity differ from each other in terms of chemical bases and reaction conditions. Considering the chemical diversity of the different classes of molecules, a single assay cannot accurately reflect their antioxidant activity. The aim of this study was to set up and apply different in vitro approaches for a fast screening of the antioxidant activity of different foods/food supplements, including wine. The methods included: 1) Folin-Ciocalteu\u2019s assay for the quantification of total polyphenol content [2]; 2) DPPH (1,1-diphenyl-2-picrylhydrazyl) spectrophotometric assay; 3) Trolox Equivalent Antioxidant Capacity (TEAC) spectrophotometric assay for measuring the capacity of the samples to scavenge ABTS radical [3]. Two novel approaches were also used in parallel: 1) High Performance Thin Layer Chromatography (HPTLC) for the semi-quantitative measure of antioxidant activity associated with wine and its specific compounds; 2) detection by an electrochemical biosensor, an analytical device that includes a biological detector coupled to a chemical transducer. Although the method based on biosensor needs further improvement, the first results indicate that this approach could be suitable for a fast measure of antioxidant activity. In conclusion, all approaches used in this research show some limitations, but when integrated they could represent a useful tool to assess antioxidant properties of foodstuff, reflecting at least in part the potential in vivo protecting activity

The Role of Wine in Modulating Inflammatory Processes: A Review

Several epidemiological studies associated the consumption of wine with the reduction of the risk factors for cardiovascular disease and certain cancers, as well as for diabetes. These conditions are characterized by inflammatory mechanisms in addition to other biological mechanisms. Acute and chronic inflammation is mediated by a plethora of biomarkers production and pathway activation. Since the health promoting properties of wine in different pathological conditions may include the reduction of inflammation, the aim of this paper was to collect and review the in vitro, in vivo, and human studies performed to evaluate the effects of wine on different models of inflammation. Although great variability in wine intake, period of consumption, and content of phenolic compounds was observed, data from both human and animal studies showed a positive modulation of inflammatory biomarkers (cytokines, coagulation parameters) and oxidative stress (mainly malondialdehyde) involved in cardiovascular function. In addition, some convincing evidence was obtained in different models suggesting a positive modulation of risk factors for gastric and intestinal inflammation. Contradictory results were obtained for metabolic syndrome and type 2 diabetes. To date, no significant paper has been published in the area of immune function. Integrating in vivo data and in vitro studies, the NF-\u3baB pathway has been identified as a critical target for the protective properties of a moderate wine consumptio

Further experimental data supporting the safety of potassium polyaspartate used as a food additive in wine stabilization

Potassium polyaspartate (KPPA) is a food additive used for wine stabilization. KPAA was included in the list of additives allowed in EU, with the Commission Regulation (EU) 2017/1399, having received a positive opinion by EFSA (European Food Safety Authority) in 2016. KPAA is rich in negative charges, which are essential for its enological function consisting in binding positive ions in order to reduce wine instability. Concerns were raised on the fact that the same binding properties could be responsible for a reduction of microelement bioavailability in humans. For this reason and for the protection of consumers' health, the binding properties of potassium polyaspartate versus three minerals (calcium, iron, magnesium) was assayed using the Size-Exclusion Chromatography (SEC). Aliquots obtained by SEC were analysed for their content in polyaspartate (by microbiuret method) and bound minerals (by ICP-OES method). The results obtained by this research shows that, when potassium polyaspartate is added to wine, the negative charges of the additive are saturated, as expected by the specific role of KPAA in tartaric stabilization. In conclusions, the effect on mineral bioavailability must be considered negligible

Controlling Ambipolar Transport and Voltage Inversion in Solution-Processed Thin-Film Devices through Polymer Blending

Ambipolar semiconductors are attracting a great interest as building blocks for photovoltaics and logic applications. Field-effect transistors built on solution-processable ambipolar materials hold strong promise for the engineering of large-area low-cost logic circuits with a reduced number of devices components. Such devices still suffer from a number of obstacles including the challenging processing, the low Ion/Ioff, the unbalanced mobility, and the low gain in complementary metal–oxide–semiconductor (CMOS)-like circuits. Here, we demonstrate that the simple approach of blending commercially available n- and p-type polymers such as P(NDI2OD-T2), P3HT, PCD-TPT, PDVT-8, and IIDDT-C3 can yield high-performing ambipolar field-effect transistors with balanced mobilities and Ion/Ioff > 10^7. Each single component was studied separately and upon blending by means of electrical characterization, ambient ultraviolet photoelectron spectroscopy, atomic force microscopy, and grazing incidence wide angle X-ray scattering to unravel the correlation between the morphology/structure of the semiconducting films and their functions. Blends of n- and p-type semiconductors were used to fabricate CMOS-like inverter circuits with state-of-the-art gains over 160 in the case of P(NDI2OD-T2) blended with PDVT-8. Significantly, our blending approach was successful in producing semiconducting films with balanced mobilities for each of the four tested semiconductor blends, although the films displayed different structural and morphological features. Our strategy, which relies on establishing a correlation between ambipolar performances, film morphology, molecular structure, and blending ratio, is extremely efficient and versatile; thus it could be applied to a wide range of polymers or solution processable small molecules

Phenolic profile and antioxidant activity of different grape (Vitis vinifera L.) varieties

In the last years, the interest in non-alcoholic grape products has considerably increased. Table grapes are largely produced in the Mediterranean area and their consumption has raised worldwide. Beside the positive pattern of nutrients, table grapes could provide benefits on human health. Among the health-promoting substances contained in table grapes, flavonoids (mainly anthocyanins, flavan-3-ols and flavonols) seem to be the most interesting. The aim of this study was the characterization of the phenolic pattern of sixteen grape varieties, and the evaluation of the associated antioxidant activity. The methods were: 1) Folin-Cocalteau's assay for the quantification of total polyphenol content; 2) DPPH (1,1,-diphenil-2—picrylhydrazyl) assay and 3) ORAC (Oxygen Radical Absorbance Capacity) spectrophotometric assays for the assessment of radical scavenging activity; 4) High Performance Liquid Chromatography (HPLC) method, coupled with electrospray ionization mass spectrometer (ESI-MS) and DAD detector was developed in order to obtain the phenolic pattern of grape samples. Data obtained in this study underline that some table grape varieties can show interesting phenolic pattern independently from the presence or not of seeds. This observation suggests that selected varieties of seedless grapes could represent an interesting source of healthy compounds, satisfying consumers' preferences and reducing concerns versus alcoholic beverages

Phenolic profile and antioxidant activity of different grape (Vitis vinifera L.) varieties

In the last years, the interest in non-alcoholic grape products has considerably increased. Table grapes are largely produced in the Mediterranean area and their consumption has raised worldwide. Beside the positive pattern of nutrients, table grapes could provide benefits on human health. Among the health-promoting substances contained in table grapes, flavonoids (mainly anthocyanins, flavan-3-ols and flavonols) seem to be the most interesting. The aim of this study was the characterization of the phenolic pattern of sixteen grape varieties, and the evaluation of the associated antioxidant activity. The methods were: 1) Folin-Cocalteau's assay for the quantification of total polyphenol content; 2) DPPH (1,1,-diphenil-2—picrylhydrazyl) assay and 3) ORAC (Oxygen Radical Absorbance Capacity) spectrophotometric assays for the assessment of radical scavenging activity; 4) High Performance Liquid Chromatography (HPLC) method, coupled with electrospray ionization mass spectrometer (ESI-MS) and DAD detector was developed in order to obtain the phenolic pattern of grape samples. Data obtained in this study underline that some table grape varieties can show interesting phenolic pattern independently from the presence or not of seeds. This observation suggests that selected varieties of seedless grapes could represent an interesting source of healthy compounds, satisfying consumers' preferences and reducing concerns versus alcoholic beverages

Fast-Response Photonic Device Based on Organic-Crystal Heterojunctions Assembled into a Vertical-Yet-Open Asymmetric Architecture

Crystalline dioctyl-3,4,9,10-perylenedicarboximide nanowires and 6,13-bis(triisopropylsilylethynyl) pentacene microplates are integrated into a vertical-yet-open asymmetrical heterojunction for the realization of a high-performance organic photovoltaic detector, which shows fast photoresponse, ultrahigh signal-to-noise ratio, and high sensitivity to weak light

Polaritonic molecular clock for all-optical ultrafast imaging of wavepacket dynamics without probe pulses

Conventional approaches to probing ultrafast molecular dynamics rely on the use of synchronized laser pulses with a well-defined time delay. Typically, a pump pulse excites a molecular wavepacket. A subsequent probe pulse can then dissociate or ionize the molecule, and measurement of the molecular fragments provides information about where the wavepacket was for each time delay. Here, we propose to exploit the ultrafast nuclear-position-dependent emission obtained due to large light–matter coupling in plasmonic nanocavities to image wavepacket dynamics using only a single pump pulse. We show that the time-resolved emission from the cavity provides information about when the wavepacket passes a given region in nuclear configuration space. This approach can image both cavity-modified dynamics on polaritonic (hybrid light–matter) potentials in the strong light–matter coupling regime and bare-molecule dynamics in the intermediate coupling regime of large Purcell enhancements, and provides a route towards ultrafast molecular spectroscopy with plasmonic nanocavitiesThis work has been funded by the European Research Council grant ERC-2016-STG-714870 and the Spanish Ministry for Science, Innovation, and Universities—AEI grants RTI2018-099737-B-I00, PCI2018-093145 (through the QuantERA program of the European Commission), and CEX2018-000805-M (through the María de Maeztu program for Units of Excellence in R&D

Antioxidants properties of food ingredients measured by different in vitro analytical approaches

Several epidemiological studies indicate that foods containing antioxidant compounds can play an important role on human health. Indeed, they may contribute in reducing the risk of chronic diseases such as cancer, inflammation, heart diseases and aging-related disorders, caused by free radicals. These are highly unstable molecules that may oxidize nucleic acids, proteins, lipids or DNA and can initiate degenerative diseases. Antioxidant compounds inhibit or quench free radical reactions by accepting or donating electrons to eliminate the unpaired condition of the radical. Among others, grapes (Vitis vinifera L.) and green tea (Camellia sinensis L.) are considered a good source of compounds with considerable antioxidant activity. However, the claimed antioxidant activity of a food or food supplements should be confirmed by analytical tests, but due to the complexity of foods and botanical ingredients (the so called "matrix effect"), the assessment of this property is often considered too expensive and complex by food industry. The aim of this study was to set-up and compare different in vitro analytical approaches suitable for the evaluation of the antioxidant activity of samples containing Vitis vinifera and Camellia sinensis. Two spectrophotometric assays were used to evaluate the total antioxidant activity associated to the samples included in the study and were based on the use of two specific radicals: 1) 2,2-azinobis-(3-ethylbenzothiazoline-6-sulphonate) radical (ABTS \u307+), 2) 1,1-diphenyl-2-picrylhydrazyl radical (DPPH \u307). The results were expressed as equivalent of gallic acid (EAG) in mg/g. A novel chromatographic approach, based on the use of High Performance Thin Layer Chromatography (HPTLC) was also applied, allowing to obtain the semi-quantitative measure of antioxidant activity associated with any specific compound in the samples analyzed. Both chromatographic and spectrophotometric assays were reliable and the results obtained comparable. The positive results of the study suggest a possible application of methods here described to obtain a rapid in vitro evaluation of the biological activity of food