1,720,993 research outputs found
PLGA nanoparticles with folate-conjugation and co-encapsulation of doxorubicin, quantum dots and SPIONS for cancer drug delivery and dual-modality imaging
No full textDoxorubicin (Dox) is a traditional chemotherapy drug, which has significant side effects, such as cardiotoxicity, mucositis, and myelosuppression. Meanwhile, many tumor cells also have a multi-drug resistant (MDR), which results in lower drug concentration in the tumor cells, and reduces its therapeutic effect. So, it is an important work for us to improve the selective delivery of DOX. Recently, using various nanocarriers encapsulated with anticancer drugs or inorganic nanoparticles which possessing special imaging effects for targeted delivery to tumor cells, gradually become a focus in the field of the nano-biotechnology research.In this study, CdSe/ZnS quantum dots, superparamagetic iron oxide nanocrystals (SPIONs) and doxorubicin (Dox) are co-encapsulated into PLGA [poly(d,l-lactic-co-glycolic acid)]-based polymeric nanoparticles using a double emulsion solvent evaporation method (W/O/W), followed by coupled to the amine group of the polyethyleneimine (PEI) pre-modified with polyethylene glycol–folic acid segments (PEI–PEG–FA), the FA-targeted PEGylated PLGA NPs (QDs/DOX/Fe3O4@PLGA/PEI–PEG–FA) were formed for tumor specific targeting drug delivery and dual-modality imaging. SEM, TEM, EDX, ξ-potential analysis, fluorescence spectroscopy, ultraviolet and visible spectrophotometer were carried out to characterize the morphology, composition, and properties of the as-prepared composite nanoparticles. The mean diameter of the QDs/DOX/Fe3O4@PLGA/PEI–PEG–FA is 317 nm, which is dispersive and sable in water. When the weight ratio of DOX to PLGA was 100 (mg DOX/g PLGA), the encapsulation efficiency and the drug loading can be reached approximately 77.81% and 7.75% respectively. And the drug release was higher in an acid pH environment (pH 4.0) than in the physiological pH environment (pH 7.0). QDs/DOX/Fe3O4@PLGA/PEI–PEG–FA nanocomposite can be targeted to tumor cells with high expression of the folate receptor, reducing the side effects of Dox on normal tissues. It may be great promising for this nanocomposite to become an effective drug delivery system for tumor-targeted drug delivery and MR/optical dual-modality imaging
Magnetic mesoporous silica nanoparticles co-delivering doxorubicin and VEGF siRNA for cervical cancer targeting therapy and MR imaging
No full textRNA interference (RNAi) has been widely applied in biology and medicine because it can down-regulate the expression of specifically targeted genes. However, considerable barriers need to be overcome for delivery naked siRNA to appropriate site including rapid degradation by serum nucleases, hepatic clearance, low transfection efficiency, off-target effect, and inefficient release from endosomes. Therefore, developing effective delivery carrier holds the key to successful in clinical application of therapeutic siRNA. Inhibition of the vascular endothelial growth factor (VEGF) expression has been proven to effectively inhibit tumor growth and metastasis. The use of single chemotherapeutic drug has shown some limitations in anti-tumor treatment. Combining chemotherapy and gene therapy may be a promising approach for cancer treatment.In this study, a multifunctional co-delivery nanocarrier based on magnetic mesoporous silica nanoparticles(M-MSNs) was designed to simultaneously deliver VEGF shRNA and doxorubicin (Dox) in vitro and in vivo. The abundant pores on the surfaces of M-MSNs improved drug loading capacity. The targeting ligand folic acid (FA) conjugated polyethyleneimine (PEI-FA) was coated on the M-MSN surfaces through electrostatic interactions. PEI-FA modification increases VEGFshRNA binging capability because of electrostatic interactions between amino groups of PEI-FA and VEGF shRNA. The nanocomplexes were characterized by scanning electron microscopy, transmission electron microscopy, Brunauer–Emmett–Teller (BET) and zeta potential assy. The M-MSN(Dox)/PEI-FA nanocomplexes had average particle size of 217 ± 1 nm and drug-loading amount of 15%. They were stable and well-dispersed in 10% fetal bovine serum and had ability to protect VEGF shRNA degradation. Confocal microscopy confirmed that the FA receptor-mediated endocytosis of the M-MSN(Dox)/PEI-FA/VEGF shRNA composite was greater than that of the M-MSN(Dox)/PEI in folate receptor-overexpressed HeLa cells. The M-MSN(Dox)/PEI-FA/VEGF shRNA nanocomplexes also demonstrated excellent gene silencing efficiency in vitro and reduced the expression of VEGF expression. The in vitro magnetic resonance (MR) imaging indicated that M-MSN(DOX)/PEI-FA could be also used as an excellent MR contrast agent. Our results suggested that the M-MSN(Dox)/PEI-FA/VEGF shRNA nanocomplexes are a safe and efficient integration platform for MR imaging and co-delivering Dox and VEGF shRNA
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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Full text linkEngineering a safe and high-efficiency delivery system for efficient RNA interference is critical for successful gene therapy. In this study, we designed a novel nanocarrier system of polyethyleneimine (PEI)-modified Fe3O4@SiO2, which allows high efficient loading of VEGF small hairpin (sh)RNA to form Fe3O4@SiO2/PEI/VEGF shRNA nanocomposites for VEGF gene silencing as well as magnetic resonance (MR) imaging. The size, morphology, particle stability, magnetic properties, and gene-binding capacity and protection were determined. Low cytotoxicity and hemolyticity against human red blood cells showed the excellent biocompatibility of the multifunctional nanocomposites, and also no significant coagulation was observed. The nanocomposites maintain their superparamagnetic property at room temperature and no appreciable change in magnetism, even after PEI modification. The qualitative and quantitative analysis of cellular internalization into MCF-7 human breast cancer cells by Prussian blue staining and inductively coupled plasma atomic emission spectroscopy analysis, respectively, demonstrated that the Fe3O4@SiO2/PEI/VEGF shRNA nanocomposites could be easily internalized by MCF-7 cells, and they exhibited significant inhibition of VEGF gene expression. Furthermore, the MR cellular images showed that the superparamagnetic iron oxide core of our Fe3O4@SiO2/PEI/VEGF shRNA nanocomposites could also act as a T2-weighted contrast agent for cancer MR imaging. Our data highlight multifunctional Fe3O4@SiO2/PEI/VEGF shRNA nanocomposites as a potential platform for simultaneous gene delivery and MR cell imaging, which are promising as theranostic agents for cancer treatment and diagnosis in the future.</p
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