Low-Power Upconversion in Poly(Mannitol-Sebacate) Networks with Tethered Diphenylanthracene and Palladium Porphyrin

[EN] Efforts to fabricate low-power up converting solid-state systems have rapidly increased in the past decade because of their possible application in several fields such as bio-imaging, drug delivery, solar harvesting or displays. The synthesis of upconverting cross-linked polyester rubbers with covalently tethered chromophores is presented here. Cross-linked films were prepared by reacting a poly(mannitol- sebacate) pre-polymer with 9,10-bis(4-hydroxymethylphenyl) anthracene (DPA-(CH2OH)2) and palladium mesoporphyrin IX. These chromophores served as emitters and sensitizers, respectively, and through a cascade of photophysical events, resulted in an anti-Stokes shifted emission. Indeed, blue emission (*440 nm) of these solid materials was detected upon excitation at 543 nm with a green laser and the power dependence of integrated unconverted intensity versus excitation was examined. The new materials display upconversion at power densities as low as 32 mW/cm2, and do not display phase de-mixing, which has been identified as an obstacle in rubbery blends comprising untethered chromophores.The authors are thankful for the financial support of the Swiss National Science Foundation (200021_13540/1 and 200020_152968), Spanish Ministry of Economy and Competitiveness (Project MAT2010/21494-C03) and the Adolphe Merkle Foundation. The authors thank Prof. Christoph Weder for his help and support.Lee, S.; Sonseca, A.; Vadrucci, R.; Giménez Torres, E.; Foster, E.; Simon, YC. (2014). Low-Power Upconversion in Poly(Mannitol-Sebacate) Networks with Tethered Diphenylanthracene and Palladium Porphyrin. Journal of Inorganic and Organometallic Polymers. 24(5):898-903. https://doi.org/10.1007/s10904-014-0063-7S898903245C. A. Parker, C. G. Hatchard. P. Chem. Soc. London, 386–387 (1962)Y.C. Simon, C. Weder, J. Mater. Chem. 22, 20817–20830 (2012)J.Z. Zhao, S.M. Ji, H.M. 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If Dante had known Phytoplankton. A comparison between literature and science through the didactics of metaphors.

This project, conducted with Classical High School students, was developed under the "Alternating School and Work Experience" program (Italian Law n. 107/2015) between the "G. Palmieri" High School of Lecce and the Environmental Protection Agency of Puglia (ARPA), Department of Lecce, in Italy. In particular, this paper describes the “HABs’ world” allegorically, in terms of one of the most famous examples of Italian literature, the Divine Comedy. Harmful algal blooms, or HABs, occur when colonies of algae, simple photosynthetic organisms that live in the sea and freshwater, grow out of control while producing toxic or harmful effects on people, fish, shellfish, marine mammals, and birds. Since HABs can be defined as “bad”, based on their negative characteristics, some of these were compared to the sinful souls that Dante and Virgil encountered along their journey into Hell. It is argued that such integration of literary and scientific contexts in terms of ecological indicators helps students understand the relationship between the sustainability of human and environmental trajectories.Key words: Phytoplankton, Harmful Algae Blooms (HABs), The Divine Comedy, Dante Alighieri, ecological indicator

Low-Power Upconversion in Poly(Mannitol-Sebacate) Networks with Tethered Diphenylanthracene and Palladium Porphyrin

Efforts to fabricate low-power upconverting solid-state systems have rapidly increased in the past decade because of their possible application in several fields such as bio-imaging, drug delivery, solar harvesting or displays. The synthesis of upconverting cross-linked polyester rubbers with covalently tethered chromophores is presented here. Cross-linked films were prepared by reacting a poly(mannitol-sebacate) pre-polymer with 9,10-bis(4-hydroxymethylphenyl) anthracene (DPA-(CH2OH)2) and palladium mesoporphyrin IX. These chromophores served as emitters and sensitizers, respectively, and through a cascade of photophysical events, resulted in an anti-Stokes shifted emission. Indeed, blue emission (~440nm) of these solid materials was detected upon excitation at 543nm with a green laser and the power dependence of integrated upconverted intensity versus excitation was examined. The new materials display upconversion at power densities as low as 32mW/cm2, and do not display phase de-mixing, which has been identified as an obstacle in rubbery blends comprising untethered chromophores. Graphical Abstract: ToC Low-power upconverting cross-linked polyester with tethered chromophores was synthesized by polycondensation of poly(mannitol-sebacate) pre-polymers with 9,10-bis(4-hydroxymethylphenyl) anthracene and palladium mesoporphyrin IX. Upconverted blue fluorescence (440nm) of these solid materials is detected upon excitation at 543nm with a green laser and the power dependence of integrated upconverted intensity versus excitation is examined in this study

Mechanochromic, Structurally Colored, and Edible Hydrogels Prepared from Hydroxypropyl Cellulose and Gelatin

Abstract: Hydroxypropyl cellulose (HPC) is an edible, cost‐effective and widely used derivative of cellulose. Under lyotropic conditions in water, HPC forms a photonic, liquid crystalline mesophase with an exceptional mechanochromic response. However, due to insufficient physical cross‐linking photonic HPC can flow freely as a viscous liquid, preventing the exploitation of this mechanochromic material in the absence of any external encapsulation or structural confinement. Here this challenge is addressed by mixing HPC and gelatin in water to form a self‐supporting, viscoelastic, and edible supramolecular photonic hydrogel. It is demonstrated that the structural coloration, mechanochromism and non‐Newtonian shear‐thinning behavior of the lyotropic HPC solutions can all be retained into the gel state. Moreover, the rigidity of the HPC‐gel provides a 69% shorter mechanochromic relaxation time back to its initial color when compared to the liquid HPC–water only system, broadening the dynamic color range of HPC by approximately 2.5× in response to a compressive pressure. Finally, the ability to formulate the HPC‐gels in a scalable fashion from only water and “food‐grade” constituents unlocks a wide range of potential applications, from response‑tunable mechanochromic materials and colorant‐free food decoration, to short‐term sensors in, for example, biodegradable “smart labels” for food packaging

Marine phycotoxin levels in shellfish-14 years of data gathered along the Italian coast

Along the Italian coasts, toxins of algal origin in wild and cultivated shellfish have been reported since the 1970s. In this study, we used data gathered by the Veterinary Public Health Institutes (IZS) and the Italian Environmental Health Protection Agencies (ARPA) from 2006 to 2019 to investigate toxicity events along the Italian coasts and relate them to the distribution of potentially toxic species. Among the detected toxins (OA and analogs, YTXs, PTXs, STXs, DAs, AZAs), OA and YTX were those most frequently reported. Levels exceeding regulatory limits in the case of OA (≤2,448 μg equivalent kg-1) were associated with high abundances of Dinophysis spp., and in the case of YTXs (≤22 mg equivalent kg-1) with blooms of Gonyaulax spinifera, Lingulodinium polyedra, and Protoceratium reticulatum. Seasonal blooms of Pseudo-nitzschia spp. occur all along the Italian coast, but DA has only occasionally been detected in shellfish at concentrations always below the regulatory limit (≤18 mg kg-1). Alexandrium spp. were recorded in several areas, although STXs (≤13,782 μg equivalent kg-1) rarely and only in few sites exceeded the regulatory limit in shellfish. Azadinium spp. have been sporadically recorded, and AZAs have been sometimes detected but always in low concentrations (≤7 μg equivalent kg-1). Among the emerging toxins, PLTX-like toxins (≤971 μg kg-1 OVTX-a) have often been detected mainly in wild mussels and sea urchins from rocky shores due to the presence of Ostreopsis cf. ovata. Overall, Italian coastal waters harbour a high number of potentially toxic species, with a few HAB hotspots mainly related to DSP toxins. Nevertheless, rare cases of intoxications have occurred so far, reflecting the whole Mediterranean Sea conditions

Nanodroplet-Containing Polymers for Efficient Low-Power Light Upconversion

Sensitized triplet-triplet-annihilation-based photon upconversion (TTA-UC) permits the conversion of light into radiation of higher energy and involves a sequence of photophysical processes between two dyes. In contrast to other upconversion schemes, TTA-UC allows the frequency shifting of low-intensity light, which makes it particularly suitable for solar-energy harvesting technologies. High upconversion yields can be observed for low viscosity solutions of dyes; but, in solid materials, which are better suited for integration in devices, the process is usually less efficient. Here, it is shown that this problem can be solved by using transparent nanodroplet-containing polymers that consist of a continuous polymer matrix and a dispersed liquid phase containing the upconverting dyes. These materials can be accessed by a simple one-step procedure that involves the free-radical polymerization of a microemulsion of hydrophilic monomers, a lipophilic solvent, the upconverting dyes, and a surfactant. Several glassy and rubbery materials are explored and a range of dyes that enable TTA-UC in different spectral regions are utilized. The materials display upconversion efficiencies of up to approximate to 15%, approaching the performance of optimized oxygen-free reference solutions. The data suggest that the matrix not only serves as mechanically coherent carrier for the upconverting liquid phase, but also provides good protection from atmospheric oxygen

Thermoresponsive Low-Power Light Upconverting Polymer Nanoparticles

We report highly efficient sensitized triplet-triplet annihilation based upconversion in aqueous suspensions of nanoparticles prepared from 9,10-diphenylanthracene- terminated poly(epsilon-caprolactone) and with platinum octaethylporphyrin as the sensitizer. The particles upconversion characteristics are strongly temperature-dependent. This feature gives insights into the mechanisms enabling the process in the nanoparticle environment, and the specific temperature range in which the photophysical parameters change is suitable for live cell and in vivo temperature sensing

Roll-to-roll fabrication of touch-responsive cellulose photonic laminates.

Hydroxypropyl-cellulose (HPC), a derivative of naturally abundant cellulose, can self-assemble into helical nanostructures that lead to striking colouration from Bragg reflections. The helical periodicity is very sensitive to pressure, rendering HPC a responsive photonic material. Recent advances in elucidating these HPC mechano-chromic properties have so-far delivered few real-world applications, which require both up-scaling fabrication and digital translation of their colour changes. Here we present roll-to-roll manufactured metre-scale HPC laminates using continuous coating and encapsulation. We quantify the pressure response of the encapsulated HPC using optical analyses of the pressure-induced hue change as perceived by the human eye and digital imaging. Finally, we show the ability to capture real-time pressure distributions and temporal evolution of a human foot-print on our HPC laminates. This is the first demonstration of a large area and cost-effective method for fabricating HPC stimuli-responsive photonic films, which can generate pressure maps that can be read out with standard cameras

Ability of phytoplankton trait sensitivity to highlight anthropogenic pressures in Mediterranean lagoons: A size spectra sensitivity index (ISS-phyto)

Size spectra exhibit common patterns of variation and predictable responses to pressures across ecosystem types, functional guilds and taxonomic groups. Here, we extend the size spectra approach to phytoplankton ecological status assessment in transitional waters by developing, testing and validating a multi-metric index of size spectra sensitivity (ISS-phyto), which integrates size structure metrics with others such as phytoplankton diversity, biomass and sensitivity of size classes to anthropogenic disturbance. The ability of various theoretical models of size spectra sensitivity to discriminate between disturbed and undisturbed ecosystems and levels of anthropogenic stress was evaluated. We used data on phytoplankton samples collected in 14 Mediterranean and Black sea transitional water ecosystems (coastal lagoons) from Italy, Albania, Greece, Bulgaria and Romania, and compared the models\u2019 efficiency by looking at their pressure\u2013impact response along salinity and enrichment gradients, the latter quantified as variations in dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorus (DIP). Data from a fifteenth Mediterranean lagoon was used for external validation purposes. Right asymmetric models of size class sensitivity, implying higher sensitivity of smaller cell size classes, were found to contribute to the ISS-phyto multimetric tool more effectively than symmetric and left asymmetric models, distinguishing disturbed from undisturbed lagoons and disturbed from undisturbed stations within the same lagoon. When based on right asymmetric sensitivity models, i.e., those that were most efficient in identifying anthropogenic impacts, ISS-phyto also showed the best fit of pressure\u2013response relationships along the salinity and enrichment gradients; at low to high levels of impact ISS response was driven by size class sensitivity and at very high impacts by phytoplankton biomass. A scheme for the classification of Ecological Quality Status based on ISS-phyto is proposed and validated. The validation procedure found that ISS-phyto is an effective and sensitive monitoring tool, robust, easy to apply and to inter-calibrate among laboratories