1,720,964 research outputs found
PROGETTAZIONE DI MACROMOLECOLE AD ARCHITETTURA COMPLESSA PER LA NANOMEDICINA
No full textPolimeri ad architettura complessa vengono sempre più utilizzati in nanomedicina, grazie alla loro capacità di attraversare barriere biologiche e di trasportare farmaci. Polimerizzazioni controllate e tecniche di “click chemistry” permettono una sintesi di macromolecole biocompatibili con peso molecolare, topologia e funzionalità regolabili
Mannosylated brush copolymers based on poly(ethylene glycol) and poly(ε-caprolactone) as multivalent lectin-binding nanomaterials
Full text linkA class of linear and four-arm mannosylated brush copolymers based on poly(ethylene glycol) and poly(ε-caprolactone) is presented here. The synthesis through ring-opening and atom transfer radical polymerizations provided high control over molecular weight and functionality. A post-polymerization azide–alkyne cycloaddition allowed for the formation of glycopolymers with different mannose valencies (1, 2, 4, and 8). In aqueous media, these macromolecules formed nanoparticles that were able to bind lectins, as investigated by concanavalin A binding assay. The results indicate that carbohydrate–lectin interactions can be tuned by the macromolecular architecture and functionality, hence the importance of these macromolecular properties in the design of targeted anti-pathogenic nanomaterials
FLUORINATED HYPERBRANCHED POLYGLYCEROL POLYMERS AND CORRESPONDING NANOPARTICLES AND ENCAPSULANTS
No full textDescribed herein are fluorinated hyper-branched polyglycerol ("HPG") polymers and corresponding synthesis methods. Also described herein are fluorinated HPG nanoparticles, drug encapsulated fluorinated HPG nanoparticles, and corresponding dispersions. Relative to corresponding non-fluorinated HPG polymers, the fluorinated HPG have desirable 19F nuclear magnetic resonance ("MR") activities for use as 19F magnetic resonance imaging ("MRI") probes. Furthermore, because the fluorinated HPG nanoparticles include, by definition, fluorine, drug loading and encapsulation efficiency is also significantly increased for fluorine containing drugs, relative to corresponding non-fluorinated HPG nanoparticles
Functional Poly(ε-caprolactone)/Poly(ethylene glycol) Copolymers with Complex Topologies for Doxorubicin Delivery to a Proteinase-Rich Tumor Environment
Full text linkDoxorubicin (DOX)-loaded polymer nanoparticles based on poly(ethylene glycol)-poly(epsilon-caprolactone) copolymers with a complex macromolecular topology are proposed to tackle the matrix metalloproteinase (MMP)-rich tumor environment. Linear, 4-arm comb-like copolymers and 4-arm brush block copolymers were synthesized through a combination of ring opening polymerization and atom transfer radical polymerization, in order to control the molar mass distribution, the arm/brush architecture, as well as the final size and DOX loading of self-assembled nanoparticles obtained by nanoprecipitation. The optimized nanocarriers were conjugated with penetrating low molecular weight protamine peptides coupled to a polyanionic inhibitory domain cleavable by matrix metalloproteinase-2 (MMP2). DOX-loaded, MMP2-activable nanocarriers were evaluated in the context of glioblastoma (GBM), a brain tumor characterized by remarkable and relevant MMP2 expression. Uptake and cytotoxicity in patient-derived GBM cells correlated with the level of MMP2 enzymatic activity in a dose-and time-dependent manner. No effects were observed in nontumoral endothelial cells that do not express MMP2. Results demonstrated that, by tuning polymer topology and peptide sequence, nanoparticle self-assembly, DOX encapsulation, and delivery can be optimized for the development of an advanced treatment for MMP2-overexpressing tumors
Engineered polyester-PEG nanoparticles prepared through a “grafting through” strategy and post-functionalization via Michael type addition
No full textFree radical polymerization (FRP) is widely used in industrial processes as an efficient and versatile method to engineer polymeric nanoparticles (PNPs) of controlled size, narrowly distributed, and of well-defined surface properties. Functional Poly(ε-caprolactone) (PCL) and poly(lactic acid) (PLA) can be utilized as macromonomers in FRP in combination with a co-polymerizable poly(ethylene glycol) (PEG), to achieve aqueous dispersions of PNPs composed of a hydrophobic polyester core and a hydrophilic PEG shell of tuneable size. For several industrial and biological applications, PNPs also need surface functionalization to provide specific physicochemical characteristics, including stimuli-responsiveness, and bioactivity. In this work, a flexible “grafting through” strategy based on Ring opening polymerization (ROP) and FRP was proposed to obtain engineered polyester-PEG nanoparticles functionalized with acrylate groups on the hydrophilic shell. The presence of acrylates allows a versatile surface functionalization through Michael-type addition with a thiolated ligand (peptide), in aqueous solution under physiological pH, with the advantage of high conversion and absence of reaction side products. A cysteine-containing cyclic RGD was used as model peptide for conjugation, due to its potential application as ligand for endothelial cells. Results indicated that active cell targeting can be achieved by using this surface functionalization approach
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
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