Navegando por Autor "Figueredo, Cleber Cunha"

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Detection of glycidic receptors in microalgae using glycodendrons as probes : a new tool for studies on cell surface interactions.
(2019) Gonçalves, Cíntia de Almeida; Figueiredo, Rute Cunha; Giani, Alessandra; Collado, Daniel; Pérez-Inestrosa, Ezequiel; Rojo Marcos, Francisco Javier; Figueredo, Cleber Cunha
Cell recognition, adhesion, and internalization are involved in infectious, reproductive, and inflammatory processes and are generally mediated by interactions between molecules located in the cell membrane and the extracellular matrix. These processes can decrease proliferation rates and they are well known for bacteria, fungi, and animals, but there is a lack of knowledge regarding autotrophic cells. Carbohydrates and proteins (e.g., lectins) are important molecules for cell interactions and information about these molecules is essential to better understand many biological phenomena in uni- or multicellular organisms. Most studies focus on the identification of the carbohydrates present on the cell surface by using labeled lectins. Alternatively, here we present a pioneer research performed by using three different labeled carbohydrates in a multivalent presentation (glycodendrons) to detect the presence of carbohydrate receptors (e.g., lectins) on cell surfaces of 12 algal species. The goal of this study was to detect some specificity in these molecular interactions, but in a reverse way in comparison to that commonly described in the literature. We tested trivalent molecules containing residuals of D-mannose, L-fucose, or N-acetyl-galactosamine to identify their bindings with the corresponding lectins expressed on cell surfaces. We envisage that our new approach could be an alternative tool for taxonomic and physiological studies on microalgae or even on other groups of organisms. Based on our results, the receptors found in the cell surface of the algal species tend to differ in composition, quantity, and distribution. The differences were mainly species-specific, since no patterns were identified at higher taxonomic level. Moreover, like lectins, labeled carbohydrates were proved to be a reliable tool for the study of cell surface composition.
High diversity of microalgae as a tool for the synthesis of different silver nanoparticles : a species-specific green synthesis.
(2021) Teixeira, Leonardo César de Moraes; Figueiredo, Rute Cunha; Andrade, Rodrigo Ribeiro de; Silva, Augusto Vieira Pontes; Arantes, Mônica L.; Giani, Alessandra; Figueredo, Cleber Cunha
Autotrophic microorganisms can be useful for the green synthesis of nanoparticles (NPs), but there is a lack of knowledge to affirm if the high variety of microorganisms is connected to a potential high diversity of NPs. Here, aqueous extracts of two cyanobacteria (Synechococcus elongatus and Microcystis aeruginosa) and four microalgae (the chlorophytes Coelastrum astroideum and Desmodesmus armatus; and the charophytes Cosmarium punctulatum and Klebsormidium flaccidum) were used for the biosynthesis of silver nanoparticles (AgNPs). The nanoparticle characterization was performed by UV–Visible absorption spectrum, Fourier Transforms Infrared (FT-IR), Transmission Electron Microscopy (TEM) and Energy Dispersive X-Ray Spectroscopy (EDS). This is the first study trying to establish some connection between the taxonomical diversity of microalgae and cyanobacteria and the synthesis of different silver nanoparticles. All algal and cyanobacterial extracts resulted in the synthesis of welldisperse and crystalline AgNPs, with no agglomerate formation. TEM analysis showed spherical AgNPs shape with size range within 1.8–5.4 nm. FTIR analysis demonstrated the presence of hydroxyl groups of peptidoglycan nature acting as stabilizing agents in the surface of the AgNPs. The nanoparticle shape and kind of stabilizing biomolecules were highly similar, but their size was significantly different, which can affect the NP properties. There was no pattern for the AgNPs in terms of the microorganism phyla. Our results showed a very high potential for the use of cyanobacteria and microalgae in the green synthesis of NPs since the variety of AgNPs obtained was species-specific.