1,720,996 research outputs found
Flow field-flow fractionation for the analysis of nanoparticles used in drug delivery
No full textStructured nanoparticles (NPs) with controlled size distribution and novel physicochemical features present fundamental advantages as drug delivery systems with respect to bulk drugs. NPs can transport and release drugs to target sites with high efficiency and limited side effects.Regulatory institutions such as the US Food and Drug Administration (FDA) and the European Commission have pointed out that major limitations to the real application of current nanotechnology lie in the lack of homogeneous, pure and well-characterized NPs, also because of the lack of well-assessed, robust routine methods for their quality control and characterization. Many properties of NPs are size-dependent, thus the particle size distribution (PSD) plays a fundamental role in determining the NP properties. At present, scanning and transmission electron microscopy (SEM, TEM) are among the most used techniques to size characterize NPs. Size-exclusion chromatography (SEC) is also applied to the size separation of complex NP samples. SEC selectivity is, however, quite limited for very large molar mass analytes such as NPs, and interactions with the stationary phase can alter NP morphology. Flow field-flow fractionation (F4) is increasingly used as a mature separation method to size sort and characterize NPs in native conditions. Moreover, the hyphenation with light scattering (LS) methods can enhance the accuracy of size analysis of complex samples. In this paper, the applications of F4-LS to NP analysis used as drug delivery systems for their size analysis, and the study of stability and drug release effects are reviewe
Quality control and purification of ready-to-use conjugated gold nanoparticles to ensure effectiveness in biosensing
Full text linkIntroduction: Gold nanoparticles (AuNPs) and their conjugates are used for
many applications in the field of sensors. Literature lacks procedures able to
separate, purify and characterize these species in native conditions without
altering them while assuring a high throughput. This technological gap can be
reduced by exploiting Asymmetrical Flow Field Flow Fractionation
multidetection platforms (AF4 multidetection).
Method: This work describes a complete set of strategies based on the AF4
system, from nanoparticle synthesis to separative method optimization to
conjugates screening and characterization, achieving quantitative control
and purification of ready-to-use conjugated Gold nanoparticles and
ensuring effectiveness in biosensing.
Results and Discussion: AF4-multidetection was used to study AuNPs with
different types of surface coating [Poly ethylene glycol, (PEG) and Citrate], their
binding behaviour with protein (Bovine serum albumin, BSA) and their stability
after conjugation to BSA. A robust but flexible method was developed, able to
be applied to different AuNPs and conjugating molecules. The morphology and
conjugation mechanism of AuNPs-BSA conjugates were evaluated by
combining online Multiangle light scattering (MALS) and offline Dynamic
Light Scattering (DLS) measures, which provided an important feature for the
quality control required to optimize bio-probe synthesis and subsequent
bioassay
Shining light on biosensors: Chemiluminescence and bioluminescence in enabling technologies
No full textChemiluminescence (CL) and bioluminescence (BL) are both fascinating natural phenomena involving the emission of light by a chemical reaction without the need for an excitation source. Both CL and BL have been used extensively in research and technology development and have become valuable tools in fields ranging from chemistry to medicine and beyond. Specifically, they offer unique advantages in the design of highly sensitive and specific detection probes for biosensors. In the CL field, novel probe designs, integration of nanomaterials, and synthetic strategies have led to enhanced sensitivity, selectivity, and versatility in biosensor applications. This in combination with portable microfluidic technologies has facilitated the detection and quantification of biomolecules, metabolites, pathogens, and environmental pollutants with high accuracy and low cost. Similarly, the exploration of bioluminescent proteins has led to the engineering of genetically encoded bioluminescent probes enabling the development of biosensors, molecular diagnostics methods, and real-time imaging and detection within living systems. Further, the development of bioluminescent reporter assays and biosensors has shown application in high-throughput screening, drug discovery, and biological mechanistic studies. The integration of BL and CL technologies into point-of-care devices has found applications in medical diagnostics, environmental monitoring, and food safety. This review highlights recent advancements in both CL and BL technologies, mainly focusing on their implications in biosensor development
Multi-environment and multi-parameter screening of stability and coating efficiency of gold nanoparticle bioconjugates in application media
Full text linkGold nanoparticles (AuNPs) and their biocompatible conjugates find wide use as transducers in (bio)sensors and as Nano-pharmaceutics. The study of the interaction between AuNPs and proteins in representative application media helps to better understand their intrinsic behaviors. A multi-environment, multi-parameter screening strategy is proposed based on asymmetric flow field flow fractionation (AF4)-multidetector. Citrate-coated AuNPs (AuCIT, 25.1 ± 0.2 nm) and PEG-coated AuNPs (AuPEG, 38.3 ± 0.8 nm) were employed with albumin as a model system. Attention was put in investigating the influence of Au/BSA mass ratios, that allowed to identify the yield-maximizing (1:1) and product-maximizing (2.5:1) conditions for the generation of AuNPs-protein conjugates. Furthermore, bioconjugate properties were thoroughly assessed across various saline media with different pH and ionic strengths. While AuNPs with PEG coating exhibit greater stability at high salinities, such as 30 mM, their conjugates are less stable over time. In contrast, although bare AuNPs are significantly affected by pH and salt concentration, once conjugates are formed, their stability surpasses that of the conjugates formed with AuPEG. The developed methodology can fill the vacancy of standard reference quality control (QC) procedures for bioconjugate synthesis and application in (bio)sensors and Nano-pharmaceutics, screening in a short time many combinations, easily scaling up to the semi-preparative scale or translating to different bioconjugates
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
A new approach for the separation, characterization and testing of potential prionoid protein aggregates through hollow-fiber flow field-flow fractionation and multi-angle light scattering
No full textProtein misfolding and aggregation are the common mechanisms in a variety of aggregation-dependent diseases. The compromised proteins often assemble into toxic, accumulating amyloid-like structures of various lengths and their toxicity can also be transferred both in vivo and in vitro a prion-like behavior. The characterization of protein interactions, degradation and conformational dynamics in biological systems still represents an analytical challenge in the prion-like protein comprehension. In our work, we investigated the nature of a transferable cytotoxic agent, presumably a misfolded protein, through the coupling of a multi-detector, non-destructive separation platform based on hollow-fiber flow field-flow fractionation with imaging and downstream in vitro tests. After purification with ion exchange chromatography, the transferable cytotoxic agentwas analyzed with Atomic Force Microscopy and statistical analysis, showing that the concentration of protein dimers and low n-oligomer forms was higher in the cytotoxic sample than in the control preparation. To assess whether the presence of these species was the actual toxic and/or self-propagating factor, we employed HF5 fractionation, with UV and Multi-Angle Light Scattering detection, to define proteins molar mass distribution and abundance, and fractionate the sample into size-homogeneous fractions. These fractions were then tested individually in vitro to investigate the direct correlation with cytotoxicity. Only the later-eluted fraction, which contains high-molar mass aggregates, proved to be toxic onto cell cultures. Moreover, it was observed that the selective transfer of toxicity also occurs for one lower-mass fraction, suggesting that two different mechanisms, acute and later induced toxicity, are in place. These results strongly encourage the efficacy of this platform to enable the identification of protein toxicants.Protein misfolding and aggregation are the common mechanisms in a variety of aggregation-dependent diseases. The compromised proteins often assemble into toxic, accumulating amyloid-like structures of various lengths and their toxicity can also be transferred both in vivo and in vitro a prion-like behavior. The characterization of protein interactions, degradation and conformational dynamics in biological systems still represents an analytical challenge in the prion-like protein comprehension. In our work, we investigated the nature of a transferable cytotoxic agent, presumably a misfolded protein, through the coupling of a multi-detector, non-destructive separation platform based on hollow-fiber flow field-flow fractionation with imaging and downstream in vitro tests. After purification with ion exchange chromatography, the transferable cytotoxic agentwas analyzed with Atomic Force Microscopy and statistical analysis, showing that the concentration of protein dimers and low n-oligomer forms was higher in the cytotoxic sample than in the control preparation. To assess whether the presence of these species was the actual toxic and/or self-propagating factor, we employed HF5 fractionation, with UV and Multi-Angle Light Scattering detection, to define proteins molar mass distribution and abundance, and fractionate the sample into size-homogeneous fractions. These fractions were then tested individually in vitro to investigate the direct correlation with cytotoxicity. Only the later-eluted fraction, which contains high-molar mass aggregates, proved to be toxic onto cell cultures. Moreover, it was observed that the selective transfer of toxicity also occurs for one lower-mass fraction, suggesting that two different mechanisms, acute and later induced toxicity, are in place. These results strongly encourage the efficacy of this platform to enable the identification of protein toxicants
Colloids in red wines: new insights from recent research
No full textDespite their significant impact on wine quality and stability, colloids in red wine remain relatively under-researched. a series of studies, developed in the context of the d-wines project, aimed to provide a comprehensive understanding of the structure, composition, and formation mechanisms of red wine colloids by studying monovarietal wines from 10 of the most significant italian red grape varieties.starting from the idea that proteins, polysaccharides, and tannins should be involved in colloid formation, 110 monovarietal red wines were analysed for these components, revealing high inter- and intra-varietal diversity [1]. despite this diversity, sds-page analysis of the proteins shows the presence of high molecular weight aggregates in all wines, whereas no free protein bands could be detected. this suggests that all proteins exist in an aggregated form, this aggregation being probably mediated by tannins. however, the studied varieties can be divided in two groups based on the mobility (dimension) of the aggregates, a distinction significantly related to the quantity of protein (bsa)-reactive tannins. this indicates that these compounds, whose quantity appears to be variety-related, determine the extent of aggregation.in a second step, an analytical method based on asymmetrical flow-field flow fractionation (af4) with online multidetection was developed to isolate and characterize red wine colloids in their native state [2]. af4 facilitated the quantification and size-separation of wine colloids. analysis of the separated colloidal fractions revealed varying proportions of proteins, polysaccharides, and phenolics, indicating that these compounds participate in colloid formation and likely determine their dimension and shape. the validity of the af4 method was confirmed by characterizing the colloidal composition of 24 italian wines selected from the previously analysed 110 red wines [3]. results confirmed the diversity in colloidal populations, which varied in size and compactness. relationships between compositional data of red wines [4] and their colloidal content and structures can be observed. in particular, red wine colloids also include polymeric pigments associated with proteins, and this can be an important aspect for the stability of red wines colour. in conclusion, the findings highlight the fundamental role of proteins in affecting the colloidal status of wine and allow to propose an updated model for colloidal aggregation in red wines. references marangon, m. et al. the macromolecular diversity of italian monovarietal red wines. oeno one 2022, 56, 81–90. marassi, v. et al. characterization of red wine native colloids by asymmetrical flow field-flow fractionation with online multidetection. food hydrocoll. 2021, 110, 106204–106204. marangon, m. et al. comprehensive analysis of colloid formation, distribution, and properties of monovarietal red wines using asymmetrical flow field-flow fractionation with online multidetection. food res. int. 2024, 187, 114414. giacosa, s. et al. diversity of italian red wines: a study by enological parameters, color, and phenolic indices. food res. int. 2021, 143, 110277–110277
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