Laboratory experiments extend our possibility to understand the behavior of organic molecules under extraterrestrial conditions. In the scope of such simulation experiments, organic molecules are often prepared as thin films, embedded in ice matrices, or adsorbed onto mineral surfaces. Albeit a single-species approach often adequately mimics the conditions to be studied, there are scenarios where the interactions between different organic molecules should be considered. In this work, we investigate the interaction of the two simplest α-amino acids, glycine and alanine, while codeposited as homogeneous nanolayers. Our results demonstrate that their interaction leads to deposition patterns, infrared signatures, and electronic properties that cannot be predicted by studying each molecular species in isolation. We conclude that organic interactions influence the photochemistry and spectroscopic signatures of biomolecules potentially present in planetary environments of interest such as Titan's surface.

BACKGROUND:Fiber optic chemical sensors (FOCS) can be rapidly integrated in future instrument suites for in-situ extraterrestrial chemical characterizations. At low development and deployment costs, they can complement the analysis of more capable instruments. The contribution of FOCS can best be exemplified by the detection of 1,3-butadiene in Titan. This analyte is an unsaturated hydrocarbon of relevance for Titan's atmospheric chemistry and geology, but its detection poses challenges for current spectroscopy and mass spectrometry space instruments. Here, we report the design of the sensing core of a future space-mission-ready FOCS tailored to detect 1,3-butadiene in Titan's hydrocarbon environments. RESULTS:We report the discovery and characterization of the first fluorescent indicator for 1,3-butadiene. The off-on detection strategy is based on an inverse electron demand Diels-Alder click-reaction between the analyte and a tetrazine indicator, yielding emissive 1,4-dihydropyridazine derivatives, as confirmed by NMR. Excitation above 415 nm enables the selective detection of 1,3-butadiene against competing unsaturated hydrocarbons present in Titan. The sensor exhibited a limit of detection of 1.1 ppm (mol mol-1) and a linear response up to the expected saturation concentration in Titan's lakes. Furthermore, the fast and irreversible reaction between the tetrazine indicator and 1,3-butadiene provides rapid sensor responses that increase with temperature. Operating the sensor at high temperatures also mitigates competing photobleaching reactions. The immobilization of the indicator in polystyrene membranes maintained its detection capability for 1,3-butadiene dissolved in hexane, an apolar solvent analogous to Titan's hydrocarbon lakes. SIGNIFICANCE:The demonstration of the solid-state functionality of the indicator marks the last step towards its integration with space-qualified instrumentation. This proof-of-principle detection of 1,3-butadiene highlights the potential of fluorescence sensing for probing exotic planetary environments. Fiber optic architectures are ideal platforms for adapting fluorescence-based chemical sensing strategies to the in-situ characterization of extraterrestrial sites.

The cryovolcanic regions of Titan offer transient opportunities for prebiotic molecules to exist in water-ammonia solutions on the surface of the Saturnian moon. The upcoming NASA's Dragonfly mission will search for high nitrogen concentrations and amino acids on Titan's equatorial terrains. Cryovolcanic features, however, are most common on the polar regions. To mitigate the distance, bubble bursting may encapsulate the prebiotic molecules into aerosols, which Titan's Hadley circulation would subsequently transport to the equator. We investigate whether alanine and glycine survive this meridional journey. Despite the unconstrained meridional wind velocities, our results suggest that the amino acids can survive the transport through the mesosphere. Dragonfly may find cryo-volcanogenic amino acids on Titan's equator. Further, the interaction between the two amino acids increased 10-fold the photodegradation rate of glycine. We justify it based on changes in the environment polarity.

The moons of Jupiter and Saturn, such as Europa and Enceladus, are strong candidates for the search for life outside of Earth. Together with the use of direct observational methods, physical and chemical processes that take place on icy moons may be studied on planetary field analogs, that is, on similar reachable locations on Earth. Fieldwork performed on planetary field analogs can test protocols and technology that may be applied on future space missions to extraterrestrial environments. The Arctic is a strong candidate for such studies. This study assesses a spectroscopic protocol for biosignature detection in the Arctic, as a proxy to icy moons. Samples of ice and the water underneath were collected by our team in different locations at and nearby Hudson Bay, Canada, and spectroscopic analysis detected the presence of humic acid in all the samples. On the contrary, biosignatures such as amino acids and β-carotene may have been present in concentrations below the limit of detection of the equipment used. With proper optimization, it will be possible to implement this simple protocol that relies on lightweight equipment in future space missions to icy moons.

Naphthalenediimide amphiphiles (NDI-as) with quaternary ammonium groups (DC4, DaP, and DaO) display unprecedented UV light-induced aggregation in solutions of water, acetonitrile and THF.

Some of the icy moons of the solar system with a subsurface ocean, such as Europa and Enceladus, are the targets of future space missions that search for potential extraterrestrial life forms. While the ice shells that envelop these moons have been studied by several spacecrafts, the oceans beneath them remain unreachable. To better constrain the habitability conditions of these moons, we must understand the interactions between their frozen crusts, liquid layers, and silicate mantles. To that end, astrobiologists rely on planetary field analogues, for which the polar regions of Earth have proven to be great candidates. This review shows how spectroscopy is a powerful tool in space missions to detect potential biosignatures, in particular on the aforementioned moons, and how the polar regions of the Earth are being used as planetary field analogues for these extra-terrestrial environments.

Phobos, a satellite of Mars, was successfully studied by flyby, orbiter, and landing missions to the Red Planet, but several questions remain about its origin, composition, and relationship to Mars. It is suggested that Phobos is either a captured body from the asteroid belt or the outer Solar System (capture scenario), or a consequence of re-accreted ejecta from Mars (in situ formation/giant impact). So far, Phobos has been characterized by its two spectral units - blue and red - with different compositional restrains. The red unit represents most of the surface, while the blue unit is focused on the Stickney crater and surroundings. In the absence of samples returned from this satellite, simulant regolith must be studied to infer various proprieties, and complement in situ studies. To date, there are three simulants of this satellite: Phobos-1C, Phobos Captured Asteroid-1 (PCA-1), and Phobos Giant Impact-1 (PGI-1). Since Phobos may have a Mars-like composition, terrestrial analogues of Mars should also be analysed. The data retrieved from the various assays performed with these planetary field analogues may be used as a database to complement future space missions to Phobos, but, ultimately, the composition of Phobos will have to be analysed by a sample-return mission.

In this work, the oxygen transport and hydrodynamic flow of the PBS Vertical-Wheel MINI™ 0.1 bioreactor were characterized using experimental data and computational fluid dynamics simulations. Data acquired from spectroscopy-based oxygenation measurements was compared with data obtained from 3D simulations with a rigid-lid approximation and LES-WALE turbulence modeling, using the open-source software OpenFOAM-8. The mass transfer coefficients were determined for a range of stirring speeds between 10 and 100 rpm and for working volumes between 60 and 100 mL. Additionally, boundary condition, mesh refinement, and temperature variation studies were performed. Lastly, cell size, energy dissipation rate, and shear stress fields were calculated to determine optimal hydrodynamic conditions for culture. The experimental results demonstrate that the kL can be predicted using Sh=1.68Re0.551Sc13G1.18, with a mean absolute error of 2.08%. Using the simulations and a correction factor of 0.473, the expression can be correlated to provide equally valid results. To directly obtain them from simulations, a partial slip boundary condition can be tuned, ensuring better near-surface velocity profiles or, alternatively, by deeply refining the mesh. Temperature variation studies support the use of this correlation for temperatures up to 37 °C by using a Schmidt exponent of 1/3. Finally, the flow was characterized as transitional with diverse mixing mechanisms that ensure homogeneity and suspension quality, and the results obtained are in agreement with previous studies that employed RANS models. Overall, this work provides new data regarding oxygen mass transfer and hydrodynamics in the Vertical-Wheel bioreactor, as well as new insights for air-water mass transfer modeling in systems with low interface deformation, and a computational model that can be used for further studies.

The photoluminescence (PL) of powders consisting of N,N'-(N,N'-dimethylethyleneamine-N ''-allyl) - 1,4,5,8-naphthaldiimide (ANDI) and polystyrene (PS) was studied as they are simply ground together and as repetitive units of copolymers. Reflectance absorption spectra showed typical solid-state ANDI CT-band from 430 nm until 600 nm by both the mixture and the copolymers. PL of the copolymers was proposed to be a CT-emission that comes from the electron donor-acceptor styrene-NDI interaction. Under excitation at 365 nm, the copolymers exhibited emission, lambda(max) similar to 500 nm, with intensity inversely proportional to the ANDI amount. The PS-ANDI ground powders displayed an excimer-like emission band at ca. 485 nm, inversely, increasing ANDI amount in the mix, PL increases. XRD analysis showed that the ANDI crystals were dismantled in some extent inside the PS matrix as they were ground together. An easy method was developed to obtain an emitting-solid system that can be useful to generate charge-transfer devices.

Four novel TADF emitters, containing phenothiazine and phenoxazine as electron-donors and benzonitrile derivatives as electron-acceptors were synthesized and fully characterized. Their photophysical (absorption and emission spectra, molar extinction coefficients, fluorescence quantum yields and lifetimes) and electrochemical properties (HOMO and LUMO energy levels) were measured, and drop-cast solid films of the four compounds were obtained to perform TADF studies. The obtained values for ΔEST indicate that these compounds are candidates for OLED applications.

The aim of this study was to valorize spent coffee grounds (SCG) into bioactive extracts for improving skin health. These extracts were obtained by subcritical water extraction (SWE) at 100 bar and temperatures up to 220 degrees C, in a semicontinuous mode. They were analyzed for phenolic acids, carbohydrates, antioxidant activity (AA) measured by the DPPH assay, ROS-scavenging activity in keratinocyte cells, and elastase and tyrosinase inhibitory activity. SCG extracts collected up to 140 degrees C had higher phenolic acids content (19.9 mg(GA)/g(dry) SCG), higher AA (EC50 of 20.6 mu g mL(-1)), and lower carbohydrate content (38 mgsugars/gdry SCG) than the fraction collected from 140 to 220 degrees C (5.7 mg(GA)/g(dry SCG), EC50 of 132.2 mu g mL(-1), and 286 mg(sugars)/g(dry SCG)). The extracts were proven to have antiaging and skin lightening effects by inhibiting elastase (99% and 97.9%) and tyrosinase (78.6% and 92.1%) activity. The extracts were incorporated in shear thinning and acidic hydrogels for topical application. Release (70%) and permeation studies (65.3 +/- 13.1 g/cm(2)) as well as cytotoxicity assays were performed to evaluate the release and permeation of bioactive compounds and the safety of hydrogels.

Treatment of trans-[PtCl2(NCR)2] 1 (R = Me (1a), Et (1b), o-ClC6H4 (1c), p-ClC6H4 (1d), p-(HCO)C6H4 (1e), p-O2NC6H4CH2 (1f)) with 1,3-diiminoisoindoline HNCC6H4C(NH)NH 2 gives access to the corresponding (1,3,5,7,9-pentaazanona-1,3,6,8-tetraenato)Pt(II) complexes [PtCl{NHC(R)NC(C6H4)NCNC(R)NH}] 3a–f, in good yields (65–70%). The reaction of trans-[PdCl2(NCMe)2] 4a with 2 furnishes (1,3,5,7,9-pentaazanona-1,3,6,8-tetraenato)Pd(II) complex [PdCl{NHC(Me)NC(C6H4)NCNC(Me)NH}] 5a, in good yield (65%). However, the reaction of trans-[PdCl2(NCR)2] 4 (R = Ph (4b), p-MeC6H4CH2 (4c), p-(HCO)C6H4 (4d), p-O2NC6H4CH2 (4e)) with 2 gives a number of unidentified products. The compounds 3a–f and 5a were characterized by IR, 1H, 13C and DEPT-135 NMR spectroscopies, elemental analyses and, in the case of the Pt(II) complex [PtCl{NHC(Me)NC(C6H4)NCNC(Me)NH}] 3a, also by X-ray diffraction analysis. Compounds 3a and 3b were also characterized by UV–Vis absorption and luminescence emission spectroscopies. Emission quantum yields of ca. 3 × 10−3 were obtained in dichloromethane solution, and luminescence lifetimes are in the order of the tens of nanoseconds. Both compounds also exhibited luminescence in solid state (polystyrene matrix), with luminescence lifetimes in the order of hundreds of nanoseconds.

Silicones are extremely versatile materials that have found manifold applications in optical sensing of chemical species. Their high gas permeability, processability, optical transparency, composition tunability, resiliency to biofilm adhesion and low cost, together with good chemical and thermal stability, have made silicones one of the polymer materials of choice to immobilize optical indicator dyes at the sensitive layer of fiber-optic gas sensors (mostly for O-2 monitoring). Silicones can also be used to manufacture optosensors for nonvolatile species, as long as they are modified with other materials to confer the required permeability to the indicator films.

A new family of Ru(II) polypyridyl complexes (C1 to C6) containing furyl- or thienyl-imidazo-phenanthroline ligands (4–6) were synthesized using microwave irradiation and characterized by elemental analysis, 1H NMR, UV–Vis absorption and fluorescence spectroscopy, FAB, ESI-MS and MALDI-TOF-MS spectrometry. On the other hand, the novel furyl- or thienyl-imidazo-phenanthroline derivatives (5–6) were synthesized through the Radziszewski reaction and completely characterized by the usual spectroscopic techniques. The interaction of the complexes with calf thymus DNA in the absence and in the presence of different quenchers (ethidium bromide, potassium hexacyanoferrate(II) and methyl viologen) has been studied by absorption spectroscopy, steady-state and single-photon timing luminescence measurements. Their electronic spectra show visible absorption peaks at 457–463 nm, with red luminescence at 603–613 nm. The emission quantum yields of these complexes are between 0.006 and 0.016 in air-equilibrated DMSO solution. Luminescence lifetimes in water lie within the 0.4–1.0 μs range, with a non-exponential behavior due to aggregation of the probe. Ru(II) complexes C3, C4, C5 and C6 show intrinsic dsDNA-binding constants of 2.74 × 105, 3.02 × 105, 1.32 × 105 and 1.63 × 105 M−1, respectively. The planar extended structure of the imidazo-phenanthroline ligands and the collected spectroscopic data suggest a partial intercalative binding mode of the novel metal probes to double-stranded DNA.

Dissertacao apresentada para a obtencao do Grau de Doutor em Quimica Sustentavel, especialidade de Quimica-Fisica Inorgânica, pela Universidade Nova de Lisboa, Faculdade de Ciencias e Tecnologia

Three new emissive 8-aminoquinoline derived probes (1)–(3) and one dinuclear Zn(II) complex (4) were synthesized and fully characterized. Their absorption spectra show maxima at 310–336nm, and fluorescence emission between 456 and 498nm. Compound (1) was characterized by single crystal X-ray diffraction. The effect upon Zn(II) and Cu(II) coordination to compounds (1)–(3) was studied by monitoring the changes in absorption and fluorescence spectra, and complemented by calculation of metal–ligand stability constants. The results indicate that compound (3) is the one that presents the most favorable geometry for coordinating two metal cations, fact that is confirmed by the synthesis of the dinuclear complex (4), with similar molecular geometry.