1,721,002 research outputs found
Development of an image Mean Square Displacement (iMSD)-based method as a novel approach to study the intracellular trafficking of nanoparticles
Full text linkFluorescence microscopy and spectroscopy techniques are commonly used to investigate complex and interacting biological systems (e.g. proteins and nanoparticles in living cells), since these techniques can explore intracellular dynamics with high time resolution at the nanoscale. Here we extended one of the Image Correlation Spectroscopy (ICS) methods, i.e. the image Mean Square Displacement, in order to study 2-dimensional diffusive and flow motion in confined systems, whose driving speed is uniformly distributed in a variable angular range. Although these conditions are not deeply investigated in the current literature, they can be commonly found in the intracellular trafficking of nanocarriers, which diffuse in the cytoplasm and/or may move along the cytoskeleton in different directions. The proposed approach could reveal the underlying system's symmetry using methods derived from fluorescence correlation concepts and could recover dynamic and geometric features which are commonly done by single particle analyses. Furthermore, it improves the characterization of low-speed flow motions, when compared to SpatioTemporal Image Correlation Spectroscopy (STICS). Although we present a specific example (lipoplexes in living cells), the emphasis is in the discussion of the method, its basic assumptions and its validation on numeric simulations. Statement of Significance Recent advances in nanoparticle-based drug and gene delivery systems have pointed out the interactions at cellular and subcellular levels as key-factors for the efficiency of the adopted biomaterials. Such biochemical and biophysical interactions drive and affect the intracellular dynamics, that is commonly characterized by means of fluorescence microscopy and spectroscopy techniques. Here we present a novel Image Correlation Spectroscopy (ICS) method as a promising tool to capture the intracellular behavior of nanoparticles with high resolution and low background's sensitivity. This study overcomes some of the approximations adopted so far, by decoupling the flow terms of the investigated dynamics and thus recovering ensemble's information from specific single particle behaviors. Finally, relevant implications for nanoparticle-based drug delivery are shown
Impact of the biomolecular corona on the structure of PEGylated liposomes
No full textDriven by the promises of gene therapy, PEGylated cationic liposomes (CLs) have been investigated for decades, but their use in the clinical setting is far from established. Such a dichotomy is due to several factors that have been ignored over the last two decades. The hardest challenge seems to occur when PEGylated CLs come into contact with a physiological environment (e.g. the blood). Recent evidence has demonstrated that PEGylation does not completely prevent protein binding (as believed so far), but a biomolecular shell, termed "biomolecular corona" (BC), covers the liposome surface. Here we show that the formation of a BC not only affects the surface properties of PEGylated CLs, but also, and significantly, their bilayer structure thus impairing their ability to safely deliver their cargo to the target site. Therefore, a mechanistic understanding of the structures emerging from liposome-protein interactions may represent a truly new paradigm for the clinical translation of PEGylated CLs
Fast and portable fluorescence lifetime analysis for early warning detection of micro- and nanoplastics in water
No full text: The presence of plastic fragments in aquatic environments, particularly at the micro- and nano-scale, has become a significant global concern. However, current detection methods are limited in their ability to reveal the presence of such particles in liquid samples. In this study, we propose the use of a fluorescence lifetime analysis system for the detection of micro- and nanoplastics in water. This approach relies on the inherent endogenous fluorescence of plastic materials and involves the collection of single photons emitted by plastic fragments upon exposure to a pulsed laser beam. Briefly, a pulsed laser beam (repetition frequency = 40 MHz) shines onto a sample solution, and the emitted light is filtered, collected, and used to trace the time distributions of the photons with high temporal resolution. Finally, the fluorescence lifetime was measured using fitting procedures and a phasor analysis. Phasor analysis is a fit-free method that allows the measurement of the fluorescence lifetime of a sample without any assumptions or prior knowledge of the sample decay pattern. The developed instrument was tested using fluorescence references and validated using unlabelled micro- and nano-scale particles. Our system successfully detected polystyrene particles in water, achieving a remarkable sensitivity with a detection limit of 0.01 mg/mL, without the need for sample pre-treatment or visual inspection. Although further studies are necessary to enhance the detection limit of the technique and distinguish between different plastic materials, this proof-of-concept study suggests the potential of the fluorescence lifetime-based approach as a rapid, robust, and cost-effective method for early warning detection and identification of plastic contaminants in aquatic environments
Time-lapse confocal imaging datasets to assess structural and dynamic properties of subcellular nanostructures
Full text linkTime-lapse optical microscopy datasets from living cells can potentially afford an enormous amount of quantitative information on the relevant structural and dynamic properties of sub-cellular organelles/structures, provided that both the spatial and temporal dimensions are properly sampled during the experiment. Here we provide exemplary live-cell, time-lapse confocal imaging datasets corresponding to three sub-cellular structures of the endo-lysosomal pathway, i.e. early endosomes, late endosomes and lysosomes, along with detailed guidelines to produce analogous experiments. Validation of the datasets is conducted by means of established analytical tools to extract the structural and dynamic properties at the sub-cellular scale, such as Single Particle Tracking (SPT) and imaging derived Mean Square Displacement (iMSD) analyses. In our aim, the present work would help other researchers in the field to reuse the provided datasets for their own scopes, and to combine their creative approaches/analyses to similar acquisitions
Insights into the effect of polyethylene terephthalate (PET) microplastics on HER2 signaling pathways
Full text link: Plastic pollution poses a significant threat to both ecosystems and human health, as fragments of microscale size are daily inhaled and ingested. Such tiny specks are defined as microplastics (MPs), and although their presence as environmental contaminants is ubiquitous in the world, their possible effects at biological and physiological levels are still not clear. To explore the potential impacts of MP exposure, we produced and characterized polyethylene terephthalate (PET) micro-fragments, then administered them to living cells. PET is widely employed in the production of plastic bottles, and thus represents a potential source of environmental MPs. However, its potential effects on public health are hardly investigated, as the current bio-medical research on MPs mainly utilizes different models, such as polystyrene particles. This study employed cell viability assays and Western blot analysis to demonstrate cell-dependent and dose-dependent cytotoxic effects of PET MPs, as well as a significant impact on HER-2-driven signaling pathways. Our findings provide insight into the biological effects of MP exposure, particularly for a widely used but poorly investigated material such as PET
Data descriptor: time-lapse confocal imaging datasets to assess structural and dynamic properties of subcellular nanostructures
No full textTime-lapse optical microscopy datasets from living cells can potentially afford an enormous amount of quantitative information on the relevant structural and dynamic properties of sub-cellular organelles/ structures, provided that both the spatial and temporal dimensions are properly sampled during the experiment. Here we provide exemplary live-cell, time-lapse confocal imaging datasets corresponding to three sub-cellular structures of the endo-lysosomal pathway, i.e. early endosomes, late endosomes and lysosomes, along with detailed guidelines to produce analogous experiments. Validation of the datasets is conducted by means of established analytical tools to extract the structural and dynamic properties at the sub-cellular scale, such as Single Particle Tracking (SPT) and imaging derived Mean Square Displacement (iMSD) analyses. In our aim, the present work would help other researchers in the field to reuse the provided datasets for their own scopes, and to combine their creative approaches/analyses to similar acquisitions
Test sierologico per coadiuvare la diagnosi e il monitoraggio del glioblastoma multiforme
No full textL’invenzione riguarda un metodo per la diagnosi del glioblastoma
multiforme che comprende l’utilizzo di nanoparticelle di ossido di
grafene e una successiva analisi di immagini, un metodo di screening o
monitoraggio di pazienti patologici e non per individuare pazienti
patologici a rischio di glioblastoma multiforme che comprende l’utilizzo
di nanoparticelle di ossido di grafene e una successiva analisi di
immagini, un kit comprendente reagenti per la diagnosi precoce del
glioblastoma multiform
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
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