1,720,961 research outputs found
Materiali bioattivi contenenti cerio: sintesi, funzionalizzazione, valutazione in-vitro
No full textQuesto studio si concentra sui vetri bioattivi mesoporosi drogati con cerio (Ce-MBG), ottimizzati per la rigenerazione dei tessuti duri, e mira ad ampliarne le applicazioni mantenendo i benefici antiossidanti del dopaggio con cerio. Il progetto ha portato allo sviluppo di nuove composizioni contenenti ioni inorganici terapeutici, al caricamento dei campioni con molecole di interesse biologico, e all'indagine su nuove morfologie e materiali compositi. In questo modo è possibile ottenere sistemi di rilascio in situ di farmaci e ioni con capacità rigenerative dei tessuti, applicabili anche alla rigenerazione dei tessuti molli. Il metodo sol-gel EISA è stato utilizzato per sintetizzare Ce-MBG (0-3.6-5.3%mol di CeO2) e Ce-MBG dopati contemporaneamente con Ce/Cu, Ce/Ag e Ce/Zn (0-2.6-3.6-5.3%mol di ossidi dopanti). Il caricamento dei Ce-MBG è stato quantificato e ottimizzato con diverse molecole di interesse, come antiossidanti naturali (polifenoli), antibiotici (amoxicillina), farmaci anti-osteoporosi (alendronato) e antinfiammatori (ibuprofene, paracetamolo), garantendo il mantenimento della bioattività dei campioni ottenuti. Le composizioni degli MBG contenenti Ce/Cu e Ce/Ag sono state ottimizzate per evitare la formazione di fasi secondarie significative, mantenere la bioattività e l'attività antiossidante CAT-mimetica, inoltre sono stati caricati con successo con una miscela di polifenoli antiossidanti aggiungendo attività antiossidante SOD-mimetica. Purtroppo, il dopaggio con Ce/Zn ha causato una riduzione significativa della capacità di formazione di idrossiapatite (HA), quindi i Ce/Zn-MBG sono stati scartati. I Ce-MBG sono stati anche incorporati in idrogel compositi iniettabili di alginato/agarosio studiati per la guarigione delle ferite croniche. La matrice dell'idrogel non ha impedito il rilascio di ioni di Si, Ca e P, né ha compromesso le proprietà antiossidanti del sistema. D'altra parte, la formazione di HA è stata fortemente rallentata, riducendo il rischio di calcificazione della ferita. Per fabbricare scaffold a base Ce-MBG con porosità su più livelli per migliorare la colonizzazione cellulare e la vascolarizzazione nel sito d'impianto, il metodo sol-gel EISA è stato combinato con il metodo foam replica. È stata poi verificata la conservazione della bioattività, la capacità di caricamento con polifenoli naturali e le attività antiossidanti CAT-mimetica e SOD-mimetica degli scaffold ottenuti. Infine, è stata investigata la sintesi di nanoparticelle di vetro bioattivo mesoporoso dopato con cerio (Ce-MBGN), regolando i parametri di sintesi per ottenere un sistema ricco di CaO, la cui composizione fosse simile a quella dei Ce-MBG. Queste nanoparticelle hanno mantenuto un'elevata capacità di formazione di HA, una morfologia porosa sfruttata per il caricamento di polifenoli, e una rapida attività antiossidante. Con dimensioni di circa 100-150 nm, queste nanoparticelle hanno l’abilità di penetrare le barriere biologiche ed provocare risposte biologiche specifiche, offrendo nuove applicazioni come sistemi di rilascio di farmaci e ioni.
Nel complesso, questi risultati hanno evidenziato la versatilità dei materiali a base di Ce-MBG nel rispondere ai bisogni critici nel campo dell'ingegneria dei tessuti duri e molli, fungendo da sistemi di rilascio in situ di farmaci e ioni.This project focuses on cerium-doped mesoporous bioactive glasses (Ce-MBGs), optimized for hard tissue regeneration, and seeks to extend their applications while maintaining the antioxidant benefits of cerium. This has led to develop new compositions that include biologically useful elements, to load the samples with beneficial molecules, to investigate new morphologies and composite materials. In this way it is possible to obtain in situ drug and ions delivery systems with tissue regenerating abilities, applicable also in soft tissue regeneration. The sol-gel EISA method was exploited to synthesize Ce-MBGs (0-3.6-5.3%mol of CeO2) and double-doped Ce/Cu, Ce/Ag and Ce/Zn-MBGs (0-2.6-3.6-5.3%mol of doping oxides). Ce-MBGs loading was quantified and optimized with different interesting molecules, such as natural antioxidants (polyphenols), antibiotics (amoxicillin), anti-osteoporotic (alendronate) and anti-inflammatory drugs (ibuprofen, paracetamol), ensuring bioactivity retention. Ce/Cu and Ce/Ag-MBGs were optimized to avoid significant secondary phase formation, maintain their bioactivity and CAT-like antioxidant activity, and were successfully loaded with a mixture of antioxidant SOD-like polyphenols. Unfortunately, doping with Zn caused a sensible decrease in hydroxyapatite (HA) formation ability, so Ce/Zn-MBGs were discarded. Ce-MBGs were incorporated in composite injectable alginate/agarose hydrogels for chronic wound healing. The hydrogel matrix did not impede the release of Si, Ca and P ions, and did not compromise the antioxidant properties of the system. On the other hand, the HA formation was strongly slowed, decreasing the risk of wound calcination. To fabricate Ce-MBGs scaffolds with multiscale porosity to enhance cell colonization and vascularization at the implant site, the sol-gel EISA method was paired with the foam replica method. The retention of bioactivity, loading ability with natural polyphenols, CAT-like and SOD-like antioxidant activities were verified. Finally, the synthesis of Ce-doped mesoporous bioactive glass nanoparticles (Ce-MBGNs) was investigated, tuning the synthesis parameters to obtain a Ca-rich system, which composition closely matched Ce-MBGs one. These nanoparticles retained a high HA forming ability, a porous morphology that was exploited for polyphenols loading, and fast antioxidant activity. With size around 100-150 nm, they could penetrate biological barriers and elicit specific biological responses, offering new drug and ion delivery applications.
Overall, these findings highlighted the versatility of Ce-MBG based materials to meet critical needs of both hard and soft tissue engineering field, working as tunable drug and ion in situ delivery systems
Loading with Biomolecules Modulates the Antioxidant Activity of Cerium-Doped Bioactive Glasses
Full text link: In order to identify new bioactive glasses (BGs) with optimal antioxidant properties, we carried out an evaluation of a series of cerium-doped BGs [Ce-BGs─H, K, and mesoporous bioactive glasses (MBGs)] loaded with different biomolecules, namely, gallic acid, polyphenols (POLY), and anthocyanins. Quantification of loading at variable times highlighted POLY on MBGs as the system with the highest loading. The ability to dismutate hydrogen peroxide (catalase-like activity) of the BGs evaluated is strongly correlated with cerium doping, while it is marginally decreased compared to the parent BG upon loading with biomolecules. Conversely, unloaded Ce-BGs show only a marginal ability to dismutate the superoxide anion (SOD)-like activity, while upon loading with biomolecules, POLY in particular, the SOD-like activity is greatly enhanced for these materials. Doping with cerium and loading with biomolecules give complementary antioxidant properties to the BGs investigated; combined with the persistent bioactivity, this makes these materials prime candidates for upcoming studies on biological systems
Cerium Containing Bioactive Glasses: A Review
Full text linkBioactive glasses (BGs) for biomedical applications are doped with therapeutic inorganic ions (TIIs) in order to improve their performance and reduce the side effects related to the surgical implant. Recent literature in the field shows a rekindled interest toward rare earth elements, in particular cerium, and their catalytic properties. Cerium-doped bioactive glasses (Ce-BGs) differ in compositions, synthetic methods, features, and in vitro assessment. This review provides an overview on the recent development of Ce-BGs for biomedical applications and on the evaluation of their bioactivity, cytocompatibility, antibacterial, antioxidant, and osteogenic and angiogenic properties as a function of their composition and physicochemical parameters
Bifunctional mesoporous glasses for bone tissue engineering: Biological effects of doping with cerium and polyphenols in 2D and 3D in vitro models
Full text linkThis study evaluates the cytocompatibility of cerium-doped mesoporous bioactive glasses (Ce-MBGs) loaded with polyphenols (Ce-MBGs-Poly) for possible application in bone tissue engineering after tumour resection. We tested MBGs powders and pellets on 2D and 3D in vitro models using human bone marrow-derived mesenchymal stem cells (hMSCs), osteosarcoma cells (U2OS), and endothelial cells (EA.hy926). Promisingly, at a low concentration in culture medium, Poly-loaded MBGs powders containing 1.2 mol% of cerium inhibited U2OS metabolic activity, preserved hMSCs viability, and had no adverse effects on EA.hy926 migration. Moreover, the study discussed the possible interaction between cerium and Poly, influencing anti-cancer effects. In summary, this research provides insights into the complex interactions between Ce-MBGs, Poly, and various cell types in distinct 2D and 3D in vitro models, highlighting the potential of loaded Ce-MBGs for post-resection bone tissue engineering with a balance between pro-regenerative and anti-tumorigenic activities.This study evaluates the cytocompatibility of cerium-doped mesoporous bioactive glasses (Ce-MBGs) loaded with polyphenols (Ce-MBGs-Poly) for possible application in bone tissue engineering after tumour resection. We tested MBGs powders and pellets on 2D and 3D in vitro models using human bone marrow-derived mesenchymal stem cells (hMSCs), osteosarcoma cells (U2OS), and endothelial cells (EA.hy926). Promisingly, at a low concentration in culture medium, Poly-loaded MBGs powders containing 1.2 mol% of cerium inhibited U2OS metabolic activity, preserved hMSCs viability, and had no adverse effects on EA.hy926 migration. Moreover, the study discussed the possible interaction between cerium and Poly, influencing anti-cancer effects. In summary, this research provides insights into the complex interactions between Ce-MBGs, Poly, and various cell types in distinct 2D and 3D in vitro models, highlighting the potential of loaded Ce-MBGs for post-resection bone tissue engineering with a balance between pro-regenerative and anti-tumorigenic activities
Ce-MBGs Loaded with Gentamicin: Characterization and In Vitro Evaluation
Full text linkMesoporous Bioactive Glasses (MBGs) are biomaterials widely used in tissue engineering, particularly for hard tissue regeneration. One of the most frequent postoperative complications following a biomaterial surgical implant is a bacterial infection, which usually requires treatment by the systemic administration of drugs (e.g., antibiotics). In order to develop biomaterials with antibiotic properties, we investigated cerium-doped MBGs (Ce-MBGs) as in situ-controlled drug delivery systems (DDSs) of gentamicin (Gen), a wide spectrum antibiotic commonly employed against bacteria responsible of postoperative infections. Here we report the optimization of Gen loading on MBGs and the evaluation of the antibacterial properties and of retention of bioactivity and antioxidant properties of the resulting materials. The Gen loading (up to 7%) was found to be independent from cerium content, and the optimized Gen-loaded Ce-MBGs retain significant bioactivity and antioxidant properties. The antibacterial efficacy was verified up to 10 days of controlled release. These properties make Gen-loaded Ce-MBGs interesting candidates for simultaneous hard tissue regeneration and in situ antibiotic release
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
Evaluation of the Properties of Bioactive Mesoporous Glasses Doped with Cerium and Loaded with Polyphenols
Full text link(1) Background: The onset of inflammation and oxidative stress after biomaterial implantation can lead to complications and prolonged recovery times. To address this, bioactive mesoporous glasses doped with cerium (0, 3.6 and 5.3 mol%) were loaded with three different biomolecules—3-hydroxyflavone, quercetin and morin hydrate—to enhance antioxidant properties while preserving bioactivity. (2) Methods: Elemental analysis, specific surface area determination, spectroscopic techniques, evaluation of antioxidant activity and in vitro bioactivity assessment were performed to characterize mesoporous glass loaded with biomolecules. (3) Results: Biomolecule loading gives values in the range of 0.5–2.0% and 10.3–39.6% for loading content and loading efficiency, respectively. The loading order is quercetin > morine hydrate > 3-hydroxyflavone, and a cerium percentage of 3.6 seems to be a good compromise. The antioxidant properties evaluated on both solids and solutions in contact with simulated biological fluids improve markedly over loaded glasses, and the most promising results are obtained with quercetin. In the most efficient systems, the bioactivity results were delayed and more evident at longer times (168 h) but were still retained. (4) Conclusions: We obtained new materials still bioactive with improved antioxidant properties that can be proposed for the regeneration of both hard and soft tissues
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
- …
