1,720,960 research outputs found
Alternative biological sources for extracellular vesicles production and purification strategies for process scale-up
Full text link: Extracellular vesicles (EVs) are phospholipidic bi-layer enclosed nanoparticles secreted naturally by all cell types. They are attracting increasing attention in the fields of nanomedicine, nutraceutics and cosmetics as biocompatible carriers for drug delivery, with intrinsic properties beneficial to human health. Scientific work now focuses on developing techniques for isolating EVs that can translate into industrial-scale production and meet rigorous clinical requirements. The science of EVs is ongoing, and many pitfalls must be addressed, such as the requirement for standard, reproducible, inexpensive, and Good Manufacturing Practices (GMP) adherent EV processing techniques. Researchers are exploring the use of alternative sources to EVs derived from mammalian cultures, such as plant EVs, as well as the use of bacteria, algae and milk. Regarding the downstream processing of EVs, many alternative techniques to the ultracentrifugation (UC) protocols most commonly used in the laboratory are emerging. In the context of process scale-up, membrane-based processes for isolation and purification of EVs are the most promising, either as stand-alone processes or in combination with chromatographic techniques. This review discusses current trends on EVs source selection and EVs downstream processing techniques, with a focus on plant-derived EVs and membrane-based techniques for EVs enrichment
Continuous Tangential Flow Filtration to Isolate Extracellular Vesicles from Dairy By-Products
No full textExtracellular vesicles (EVs) are nanoparticles with high diagnostic and therapeutic potential, but their large-scale application remains hampered by challenges related to the availability of suitable sources and isolation techniques. In this study, we investigated sweet whey, the main byproduct of the dairy industry, as an innovative source of EVs. Whey was pretreated by centrifugation, followed by purification and concentration using a two-stage tangential flow filtration (TFF) process, the first
operating in diafiltration mode and the second in concentration mode. Two TFF hollow fiber membrane modules were tested: a microfiltration membrane with a pore size of 0.15 μm and an ultrafiltration membrane with a molecular weight cutoff of 750 kDa. Process performance was evaluated using several analytical techniques and parameters, with impurity removal, EV loss, and relative EV content in the final product calculated from HPLC size exclusion chromatography results as the primary metrics. TFF performance was compared with a standard ultracentrifugation protocol.TFF microfiltration outperformed ultracentrifugation in terms of both final product purity (>99%), relative EV content (>57%), EVloss (<6%), and process throughput. However, TFF ultrafiltration completely prevented EV loss (0.04%), but it was not as efficient at removing impurities (<98%) when compared to microfiltration. This study demonstrates for the first time that sweet whey is a low-cost, sustainable, and widely available source of EVs. By combining these properties with a highly efficient, continuous, and easily scalable TFF process, we have addressed the barriers that limit the industrial-scale therapeutic application of EVs, further capitalizing on the use of a byproduct rather than consuming a primary resource
Análisis de afinidad de Escherichia coli sobre películas plásticas con recubrimientos multicapa
No full textLa detección y monitoreo de contaminantes potencialmente peligrosos para la salud de la población, tales como los microorganismos, es uno de los desafíos actuales de la comunidad científica. La necesidad de disponer de nuevas tecnologías de detección que sean compactas, portables, fáciles de operar, y con buena performance y durabilidad ha llevado a desarrollar y estudiar nuevos materiales de sensado. En este contexto, el grafeno se presenta como un material promisorio para el desarrollo de plataformas de sensado de microorganismos gracias a sus propiedades fisicoquímicas únicas y, particularmente, su biocompatibilidad. En este trabajo, se propone el estudio de la afinidad de la bacteria Escherichia coli (EC) DH5-α sobre un material de sensado obtenido a partir de películas de polietilen tereftalato (PET) recubiertas con grafeno producido por exfoliación química de grafito.Fil: Berthe, Jazmin Aldana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Giancaterino, Sara. Universidad de Bologna; ItaliaFil: Castillo, Luciana Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Boi, Cristiana. Universidad de Bologna; ItaliaFil: Barbosa, Silvia Elena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaXV Simposio Argentino de Polímeros; I Congreso Argentino de Materiales CompuestosArgentinaConsejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiale
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Isolation of extracellular vesicles from citrus limon fruit through membrane-based techniques.
Full text linkThe project is aimed at the development of a membrane-based protocol for the isolation of plant-derived extracellular vesicles. In particular, citrus limon fruit is selected as source material, due to its beneficial phyto-properties, availability and cheapness. In the chosen strategy the focus is placed upon the development of a protocol potentially suitable for large-scale operations, conversely to differential ultracentrifugation method, the benchmark in extracellular vesicles production, whose applicability is limited to lab-scale operations. In this context dead-end and crossflow MF/UF units are compared, both as concentration and purification steps. Followingly, the isolated vesicles ware analysed and characterized with SEC liquid chromatography and both physical and biochemical methods. Finally, passive cargo loading techniques are applied to the isolated vesicles to test their encapsulation capability with bioactive phytocomponents, as curcumin
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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