Synthesis and characterization of a water-soluble pentamethine indocyanine dye for peptide labeling

A water-soluble pentamethine cyanine dye was synthesized for further conjugation with peptides. The dye preparation was accomplished by solution-phase chemistry and the synthesized compounds were characterized by the usual techniques (nuclear magnetic resonance, UV-vis ab-sorption and fluorescence spectroscopies and mass spectrometry). The photophysical properties of cyanine 4 were studied in aqueous media, namely in phosphate-buffered saline (PBS) at pH 7.4. Sulfo-Cy5 carboxylic acid 4 exhibited a narrow absorption band and a high molar extinction coef-ficient (log ε = 5.11) at 646 nm. The wavelength of maximum fluorescence was found in the near-infrared (NIR) region at 661 nm. Therefore, due to its excellent spectral proprieties, good wa-ter solubility and emission in the NIR region, dye 4 can be employed in the synthesis of fluores-cence resonance energy transfer (FRET) probes for studying enzymatic hydrolysis in vitro.This research was funded by the Foundation for Science and Technology (FCT) for financial support to CQ/UM (UID/QUI/00686/2020) and project PTDC/QUI-COL/28052/2017 and a PhD grant to C. D. F. Martins (SFRH/BD/05277/2020). The NMR spectrometer Bruker Avance III 400 is part of the National NMR Network and was purchased within the framework of the National Program for Scientific Re-equipment, contract REDE/1517/RMN/2005 with funds from POCI 2010 (FEDER) and FCT

Dabcyl as a naked eye colorimetric chemosensor for palladium detection in aqueous medium

Industrial activity has raised significant concerns regarding the widespread pollution caused by metal ions, contaminating ecosystems and causing adverse effects on human health. Therefore, the development of sensors for selective and sensitive detection of these analytes is extremely important. In this regard, an azo dye, Dabcyl 2, was synthesised and investigated for sensing metal ions with environmental and industrial relevance. The cation binding character of 2 was evaluated by colour changes as seen by the naked eye, UV-Vis and 1H NMR titrations in aqueous mixtures of SDS (0.02 M, pH 6) solution with acetonitrile (99:1, v/v). Out of the several cations tested, chemosensor 2 had a selective response for Pd2+, Sn2+ and Fe3+, showing a remarkable colour change visible to the naked eye and large bathochromic shifts in the UV-Vis spectrum of 2. This compound was very sensitive for Pd2+, Sn2+ and Fe3+, with a detection limit as low as 5.4 × 10−8 M, 1.3 × 10−7 M and 5.2 × 10−8 M, respectively. Moreover, comparative studies revealed that chemosensor 2 had high selectivity towards Pd2+ even in the presence of other metal ions in SDS aqueous mixtures.FCT - Fundação para a Ciência e a Tecnologia(PTDC/QUI-COL/28052/2017)This research was funded by the Foundation for Science and Technology (FCT) for financial support to CQ-UM (UID/QUI/00686/2020) and project PTDC/QUI-COL/28052/2017 and a PhD grant to C.D.F. Martins (SFRH/BD/05277/2020). The NMR spectrometer Bruker Avance III 400 is part of the National NMR Network and was purchased within the framework of the National Program for Scientific Re-equipment, contract REDE/1517/RMN/2005, with funds from POCI 2010 (FEDER) and FCT

Chromo-fluorogenic detection of cyanide ion with a cyanine probe

Due to the extreme toxicity of cyanide in biological systems and its widespread presence in the environment, great efforts have been focused on developing sensitive and selective methods for cyanide detection. In this regard, a sulfo-cyanine dye 1 was evaluated as a colorimetric and fluorimetric probe for various anions. Chemosensing studies revealed that this compound exhib-ited remarkable selectivity and sensitivity for CN− in acetonitrile solution, with a marked colour change from cyan to colourless and the fluorescence emission was switched off. The detection lim-it was estimated to be as low as 0.45 μM, and the binding mode was studied using NMR techniques.This research was funded by Fundação para a Ciência e Tecnologia—FCT (Portugal) through CQ-UM (UID/QUI/00686/2020), project PTDC/QUI-OUT/3143/2021 and a PhD grant to C. D. F. Martins (SFRH/BD/05277/2020). The NMR spectrometer Bruker Avance III 400 is part of the National NMR Network and was purchased within the framework of the National Program for Scientific Re-equipment, contract REDE/1517/RMN/2005 with funds from POCI 2010 (FEDER) and FCT

Intermolecular quenching of edans/Dabcyl Donor–Acceptor FRET pair

The intermolecular quenching between 5-(2′-aminoethyl)aminonaphthalene sulfonic acid (Edans) and 4-[[4′-(N,N-dimethylamino)phenyl]diazenyl]benzoic acid (Dabcyl) was studied by photometric and fluorimetric measurements at pH 7.5 in phosphate buffer. The spectral properties of the Edans/Dabcyl donor–acceptor pair were determined and Dabcyl exhibited an intense absorption band at 463 nm, contributing to the quenching efficiency. We also found the primary requirement for fluorescence resonance energy transfer (FRET), the excellent overlap between the fluorescence emission spectrum of the donor molecule and the absorption spectrum of the acceptor molecule, resulting in efficient energy transfer. The quenching mechanism was studied using the Stern–Volmer plot, confirming that this FRET pair was involved in a dynamic quenching process.The authors acknowledge Fundação para a Ciência e Tecnologia (Portugal) for funding through CQUM (Pest-C/QUI/UI0686/2018) and project PTDC/QUI-COL/28052/2017

A new fluorogenic substrate for granzyme B based on fluorescence resonance energy transfer

The synthesis and characterization of a new fluorogenic substrate for granzyme B (GzmB) is reported. The substrate design was based on the fluorescence resonance energy transfer (FRET) principle using 5-(2′-aminoethyl)aminonaphthalene sulfonic acid (Edans) and 4-[[4′-(N,N-dimethylamino)phenyl]diazenyl]benzoic acid (Dabcyl) as a donor–acceptor pair, linked to a specific sequence for GzmB (AAD), with an additional amino acid as the anchoring point (K). The tetrapeptide was synthesized by microwave-assisted solid-phase peptide synthesis (MW-SPPS) and coupled to Dabcyl and Edans at its N- and C-termini, respectively. The obtained probe was purified by semi-preparative HPLC and characterized by NMR, UV/Vis absorption and fluorescence spectroscopy and mass spectrometry.The authors acknowledge Fundação para a Ciência e Tecnologia—FCT (Portugal), for funding through CQUM (UIDB/00686/2020) and project PTDC/QUI-COL/28052/2017. The NMR spectrometer Bruker Avance III 400 is part of the National NMR Network and was purchased within the framework of the National Program for Scientific Re-equipment, contract REDE/1517/RMN/2005 with funds from POCI 2010 (FEDER) and FCT

Pineapple (Ananas comosus L.) by-products valorization: Novel bio ingredients for functional foods

Pineapple is consumed on a large scale around the world due to its appreciated sensorial characteristics. The industry of minimally processed pineapple produces enormous quantities of by-products (3050%) which are generally undervalued. The end-of-life of pineapple by-products (PBP) can be replaced by reuse and renewal flows in an integrated process to promote economic growth by reducing consumption of natural resources and diminishing food waste. In our study, pineapple shell (PS) and pineapple core (PC), vacuum-packed separately, were subjected to moderate hydrostatic pressure (225 MPa, 8.5 min) (MHP) as abiotic stress to increase bromelain activity and antioxidant capacity. Pressurized and raw PBP were lyophilized to produce a stable powder. The dehydrated samples were characterized by the following methodologies: chemical and physical characterization, total phenolic compounds (TPC), antioxidant capacity, bromelain activity, microbiology, and mycotoxins. Results demonstrated that PBP are naturally rich in carbohydrates (6688%), insoluble (1628%) and soluble (24%) fiber, and minerals (45%). MHP was demonstrated to be beneficial in improving TPC (24%), antioxidant activity (26%), and bromelain activity (632%) without affecting the nutritional value. Furthermore, microbial and mycotoxical analysis demonstrated that powdered PC is a safe by-product. PS application is possible but requires previous decontamination to reduce the microbiological load.Fundação para a Ciência e a Tecnologia (FCT), Portugal, through a PhD grant (SFRH/BD/109124/2015) and for financing the PhD grant of Renata A. Amaral (SFRH/BD/146009/2019). This work was supported by the national funding of FCT, under the scope of the strategic funding to the research units LEAF (UIDB/04129/2020), LAQV-REQUIMTE Associate Laboratory (UIDB/50006/2020) and CEB (UIDP/04469/2020) through national funds and where applicable co-financed by the FEDER, within the PT2020 Partnership Agreement, and PDR2020-101-031856 ProEnergy—New food products and bioenergy from fruits of low commercial value and agro industrial wastesinfo:eu-repo/semantics/publishedVersio

A viewpoint on the use of microalgae as an alternative feedstuff in the context of pig and poultry feeding - a special emphasis on tropical regions

With the current increase in meat and animal products consumption, there is a need to make production systems more sustainable. The use of microalgae in monogastric feeds, replacing widely used conventional feedstuffs such corn and soybean, can be a solution to overcome this problem. Several studies have shown promising results in the use of microalgae in feeding of both pigs and poultry. However, there are several important constraints associated to the production of microalgae. Such constraints are particularly limiting in the context of tropical regions. Research and scientific development on microalgae production systems are thus essential so that may be widely used in monogastric feeding. Herein, we conduct an overview of the major findings in the use of microalgae in the context of monogastric feeding and analyse the major constraints associated to its production and use, particularly in the specific context of tropical regions.info:eu-repo/semantics/submittedVersio

Colloidal nanomaterials for water quality improvement and monitoring

Water is the most important resource for all kind forms of live. It is a vital resource distributed unequally across different regions of the globe, with populations already living with water scarcity, a situation that is spreading due to the impact of climate change. The reversal of this tendency and the mitigation of its disastrous consequences is a global challenge posed to Humanity, with the scientific community assuming a major obligation for providing solutions based on scientific knowledge. This article reviews literature concerning the development of nanomaterials for water purification technologies, including collaborative scientific research carried out in our laboratory (nanoLAB@UA) framed by the general activities carried out at the CICECO-Aveiro Institute of Materials. Our research carried out in this specific context has been mainly focused on the synthesis and surface chemical modification of nanomaterials, typically of a colloidal nature, as well as on the evaluation of the relevant properties that arise from the envisaged applications of the materials. As such, the research reviewed here has been guided along three thematic lines: 1) magnetic nanosorbents for water treatment technologies, namely by using biocomposites and graphite-like nanoplatelets; 2) nanocomposites for photocatalysis (e.g., TiO2/Fe3O4 and POM supported graphene oxide photocatalysts; photoactive membranes) and 3) nanostructured substrates for contaminant detection using surface enhanced Raman scattering (SERS), namely polymers loaded with Ag/Au colloids and magneto-plasmonic nanostructures. This research is motivated by the firm believe that these nanomaterials have potential for contributing to the solution of environmental problems and, conversely, will not be part of the problem. Therefore, assessment of the impact of nanoengineered materials on eco-systems is important and research in this area has also been developed by collaborative projects involving experts in nanotoxicity. The above topics are reviewed here by presenting a brief conceptual framework together with illustrative case studies, in some cases with original research results, mainly focusing on the chemistry of the nanomaterials investigated for target applications. Finally, near-future developments in this research area are put in perspective, forecasting realistic solutions for the application of colloidal nanoparticles in water cleaning technologies.publishe

Cymoxanil inhibits respiration through inhibition of mitochondrial complex IV

Cymoxanil is a synthetic acetamide fungicide, used against oomycetes. It was first introduced in 1977 and can be used against downy mildew diseases induced by Plasmopara viticola in grapevine cultures and late blight diseases caused by Phytophthora infestans, in tomatoes and potatoes cultures. This fungicide is used in mixed formulations and its higher solubility enables a relatively widespread occurrence in toxic concentrations in aquatic environments. Although it has been used over the years, its biochemical mode of action is not yet known. Some studies reported that cymoxanil affects growth, respiration, DNA, RNA and protein synthesis and RNA polymerase activity of Phytophthora infestans, and it was reported to inhibit cell growth and biomass production and decrease the respiration rate of S. cerevisiae. Using yeast S. cerevisiae as model, we further characterized its effect on mitochondria. We found that whole cells treated with cymoxanil present a higher inhibition of oxygen consumption after 3 h of treatment that remains over time. Using isolated mitochondria, we observe that cymoxanil inhibits respiratory rate of yeast cells by inhibiting oxidative phosphorylation, through inhibition of complex IV activity. Although other targets cannot be excluded, our data provide new information about mode of action of cymoxanil that can be instrumental to drive informed management regarding the use of this fungicide.info:eu-repo/semantics/publishedVersio

Peripheral axonal ensheathment is regulated by RalA GTPase and the exocyst complex

Funding This work was supported by H2020 Marie Skłodowska-Curie Actions [H2020- GA661543-Neuronal Trafficking to R.O.T.], Fundo Regional para a Ciência e Tecnologia [IF/00392/2013/CP1192/CT0002 to R.O.T.] and iNOVA4Health (UID/Multi/04462/2013) (co-funded by FCT-FEDER-PT2020).Axon ensheathment is fundamental for fast impulse conduction and the normal physiological functioning of the nervous system. Defects in axonal insulation lead to debilitating conditions, but, despite its importance, the molecular players responsible are poorly defined. Here, we identify RalA GTPase as a key player in axon ensheathment in Drosophila larval peripheral nerves. We demonstrate through genetic analysis that RalA action through the exocyst complex is required in wrapping glial cells to regulate their growth and development. We suggest that the RalA-exocyst pathway controls the targeting of secretory vesicles for membrane growth or for the secretion of a wrapping glia-derived factor that itself regulates growth. In summary, our findings provide a new molecular understanding of the process by which axons are ensheathed in vivo, a process that is crucial for normal neuronal function.publishersversionpublishe