1,720,962 research outputs found
Sviluppo di biomateriali ibridi per applicazioni teranostiche
No full textLa sintesi di silice mesoporosa a pori larghi (LPMS) offre un approccio promettente per ospitare e stabilizzare molecole bioattive con applicazioni farmaceutiche, essenziale per mantenere la loro attività biologica. A differenza della silice mesoporosa classica (MS), che presenta limitazioni dovute alle ridotte dimensioni dei pori (2–5 nm) che possono causare ostruzione dei pori e insufficiente capacità di caricamento, le strutture LPMS presentano pori significativamente più grandi (20–60 nm e 200–600 nm). Questi pori più grandi consentono un caricamento più efficiente, la stabilizzazione e il rilascio controllato di molecole bioattive.
Le LPMS sono sintetizzate utilizzando una soluzione acquosa acida di tetraetil ortosilicato con agenti formanti pori (Pluronic F127® e mesitilene), attraverso reazioni idrotermiche e assistite da microonde. Ottimizzazioni nel tempo di reazione e nell'uso di tensioattivi sono state effettuate per migliorare le proprietà del materiale. Studi di caricamento con Nisina, un peptide antibatterico policiclico con dimensioni di 4–6 nm, hanno dimostrato un'efficienza di caricamento significativamente più elevata (LE%) per le LPMS rispetto alle MS, come confermato da analisi UV-Vis, analisi elementare e termogravimetria. Gli studi sul rilascio in fluido corporeo simulato (SBF) hanno evidenziato un profilo di rilascio controllato per le LPMS su scale temporali estese, con la microscopia elettronica a scansione (SEM) che ha confermato la conservazione dell'integrità strutturale e della resistenza meccanica dopo i test di rilascio.
Inoltre, le LPMS sono state ulteriormente funzionalizzate incorporando ioni come Ca2+ e Ga3+, noti per le loro proprietà bioattive, antibatteriche e anticancro. Queste LPMS modificate hanno dimostrato proprietà di caricamento e rilascio superiori, in particolare in termini di rilascio di Ca2+ e Ga3+ in SBF, come mostrato dalla spettroscopia a emissione ottica con plasma accoppiato induttivamente (ICP-OES). Il comportamento bioattivo di queste strutture è stato confermato tramite spettroscopia infrarossa a trasformata di Fourier (FT-IR), SEM-EDS e diffrazione a raggi X su polveri (XRPD). Questi risultati indicano che le LPMS non solo offrono migliori caratteristiche di caricamento e rilascio per le molecole bioattive rispetto alla MS classica, ma presentano anche proprietà bioattive, rendendole candidate promettenti per applicazioni nella rigenerazione ossea e in altri campi biomedici.The synthesis of large pore mesoporous silica (LPMS) offers a promising approach for accommodating and stabilizing bioactive molecules with pharmaceutical applications, which is crucial for maintaining their biological activity. Unlike classical mesoporous silica (MS), which suffers from limitations due to smaller pore sizes (2–5 nm) that can lead to pore blocking and insufficient loading capacity, LPMS structures feature significantly larger pores (20–60 nm and 200–600 nm). These larger pores enable more efficient loading, stabilization, and controlled release of bioactive molecules.
LPMSs are synthesized using an acidic water solution of tetraethyl orthosilicate with pore-forming agents (Pluronic F127® and mesitylene), through hydrothermal and microwave-assisted reactions. Optimizations in reaction time and surfactant use have been performed to enhance the material properties. Loading studies using Nisin, a polycyclic antibacterial peptide with dimensions of 4–6 nm, demonstrated a significantly higher loading efficiency (LE%) for LPMSs compared to MS, as confirmed by UV-Vis, elemental analysis, and thermogravimetric analysis. Release studies in simulated body fluid (SBF) highlighted a controlled release profile for LPMSs over extended time scales, with scanning electron microscopy (SEM) confirming the preservation of structural integrity and mechanical strength after the release tests.
Moreover, LPMSs were further functionalized by incorporating ions such as Ca2+ and Ga3+, known for their bioactive, antibacterial, and anticancer properties. These modified LPMSs demonstrated superior loading and release properties, particularly in terms of Ca2+ and Ga3+ release in SBF, as shown by inductively coupled plasma—optical emission spectroscopy (ICP-OES). The bioactive behavior of these structures was confirmed through Fourier-transform infrared spectroscopy (FT-IR), SEM-EDS, and X-ray powder diffraction (XRPD). These results indicate that LPMSs not only provide better loading and release characteristics for bioactive molecules compared to classical MS but also exhibit bioactive properties, making them promising candidates for applications in bone tissue regeneration and other biomedical fields
Applications of Radiolabelled Curcumin and Its Derivatives in Medicinal Chemistry
Full text linkCurcumin is a natural occurring molecule that has aroused much interest among researchers
over the years due to its pleiotropic set of biological properties. In the nuclear medicine field,
radiolabelled curcumin and curcumin derivatives have been studied as potential radiotracers for the
early diagnosis of Alzheimer’s disease and cancer. In the present review, the synthetic pathways,
labelling methods and the preclinical investigations involving these radioactive compounds are
treated. The studies entailed chemical modifications for enhancing curcumin stability, as well as its
functionalisation for the labelling with several radiohalogens or metal radionuclides (fluorine-18,
technetium-99m, gallium-68, etc.). Although some drawbacks have yet to be addressed, and none
of the radiolabelled curcuminoids have so far achieved clinical application, the studies performed
hitherto provide useful insights and lay the foundation for further developments
Alginate Beads Containing Cerium-Doped Mesoporous Glass and Curcumin: Delivery and Stabilization of Therapeutics
Full text linkCancer is a leading cause of death worldwide, its genesis and progression are caused by homeostatic errors, and reactive oxygen species play a major role in promoting aberrant cancer homeostasis. In this scenario, curcumin could be an interesting candidate due to its versatile antioxidant, anti-inflammatory, anti-tumor, anti-HIV, and anti-infection properties. Nonetheless, the major problem related to its use is its poor oral bioavailability, which can be overcome by encapsulating it into small particles, such as hydrogel beads containing mesoporous silica. In this work, various systems have been synthesized: starting from mesoporous silica glasses (MGs), cerium-containing MGs have been produced; then, these systems have been loaded with 4 to 6% of curcumin. Finally, various MGs at different compositions have been included in alginate beads. In vitro studies showed that these hybrid materials enable the stabilization and effective delivery of curcumin and that a synergic effect can be achieved if Ce3+/Ce4+ and curcumin are both part of the beads. From swelling tests, it is possible to confirm a controlled curcumin release compartmentalized into the gastrointestinal tract. For all beads obtained, a curcumin release sufficient to achieve the antioxidant threshold has been reached, and a synergic effect of cerium and curcumin is observed. Moreover, from catalase mimetic activity tests, we confirm the well-known catalytic activity of the couple Ce3+/Ce4+. In addition, an extremely good radical scavenging effect of curcumin has been demonstrated. In conclusion, these systems, able to promote an enzymatic-like activity, can be used as drug delivery systems for curcumin-targeted dosing
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
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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