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1.
Environ Sci Technol ; 55(5): 3001-3008, 2021 Mar 02.
Artículo en Inglés | MEDLINE | ID: mdl-33566594

RESUMEN

The aim of this study is to demonstrate how the flow and diffusion of nanoplastics through a salinity gradient (SG), as observed in mangrove swamps (MSPs), influence their aggregation pathways. These two parameters have never yet been used to evaluate the fate and behavior of colloids in the environment, since they cannot be incorporated into classical experimental setups. Land-sea continuums, such as estuaries and MSP systems, are known to be environmentally reactive interfaces that influence the colloidal distribution of pollutants. Using a microfluidic approach to reproduce the SG and its dynamics, the results show that nanoplastics arriving in a MSP are fractionated. First, a substantial fraction rapidly aggregates to reach the microscale, principally governed by an orthokinetic aggregation process and diffusiophoresis drift. These large nanoplastic aggregates eventually float near the water's surface or settle into the sediment at the bottom of the MSP, depending on their density. The second, smaller fraction remains stable and is transported toward the saline environment. This distribution results from the combined action of the spatial salt concentration gradient and orthokinetic aggregation, which is largely underestimated in the literature. Due to nanoplastics' reactive behavior, the present work demonstrates that mangrove and estuarine systems need to be better examined regarding plastic pollution.

2.
Chemosphere ; 262: 127784, 2021 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-32777612

RESUMEN

While several studies have investigated the potential impact of nanoplastics, proof of their occurrence in our global environment has not yet been demonstrated. In the present work, by developing an innovative analytical strategy, the presence of nanoplastics in soil was identified for the first time. Our results demonstrate the presence of nanoplastics with a size ranging from 20 to 150 nm and covering three of the most common plastic families: polyethylene, polystyrene and polyvinyl chloride. Given the amount of organic matter in the soil matrix, the discrimination and identification of large nanoplastic aggregates are challenging. However, we provided an innovative methodology to circumvent the organic matter impact on nanoplastic detection by coupling size fractionation to molecular analysis of plastics. While photodegradation has been considered the principal formation pathway of nanoplastics in the environment, this study provides evidence, for the first time, that plastic degradation and nanoplastic production can, however, occur in the soil matrix. Moreover, by providing an innovative and simple extraction/analysis method, this study paves the way to further studies, notably regarding nanoplastic environmental fate and impacts.


Asunto(s)
Monitoreo del Ambiente/métodos , Microplásticos/análisis , Nanopartículas/análisis , Contaminantes del Suelo/análisis , Suelo/química , Francia , Tamaño de la Partícula , Polietileno/análisis , Poliestirenos/análisis , Cloruro de Polivinilo/análisis
3.
Mar Pollut Bull ; 160: 111716, 2020 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-33181971

RESUMEN

Due to the dramatic quantity of plastic debris released into our environment, one of the biggest challenges of the next decades is to trace and quantify microplastics (MPs) in our environments, especially to better evaluate their capacity to transport other contaminants such as trace metals. In this study, trace elements (Fe, Cu, Zn, As, Cd, Sn, Sb, Pb, and U) were analyzed in the microplastic subsurface (200 µm) using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Microplastics subjected to the marine environment were collected on beaches (Guadeloupe) exposed to the north Atlantic gyre. We established a strategy to discriminate sorbed contaminants from additives based on the metal concentration profiles in MP subsurface using qualitative and quantitative approaches. A spatiotemporal correlation of the sorption pattern was proposed to compare MPs in terms of relative exposure time and time-weighted average concentrations in the exposure media.


Asunto(s)
Terapia por Láser , Oligoelementos , Guadalupe , Microplásticos , Plásticos , Oligoelementos/análisis
4.
Environ Pollut ; 268(Pt B): 115170, 2020 Jul 11.
Artículo en Inglés | MEDLINE | ID: mdl-33035875

RESUMEN

Fate, transport and accumulation of nanoplastics have attracted considerable attention in the past few years. While actual researches have been focused on nanoplastics dispersed or aggregated in different environmental system, no study have been focused on the possibility that nanoplastics are co-transported with other natural or anthropogenic materials. Therefore, the large quantity of debris released in the environment, such as cigarette butts (CGB), could be part of the nanoplastics fate and behavior. Here we show the considerable sorption capacities of cigarette filters for nanoplastics. To address this topic, we chose polystyrene-based nanoplastics with similar state of charge (according to the physico-chemical characteristic of the zeta potential -45 to -40 mV) but with different sizes (50-800 nm) and morphologies. A kinetic approach to sorption in fresh water (pH = 8.05; 179.5 µS cm-1) at room temperature was carried out by means of the flow field flow analysis method (AF4) to determine the partition coefficients and water sampling rates between nanoplastics and cigarette butts. Using different models of, more or less environmentally relevant, nanoplastics (NPTs) and adequate analytical strategies, we found partition coefficients between the NPTs and CGBs ranged from 102 to 104 in freshwater conditions. We demonstrated that the physical features of the NPTs (size and morphology) have an influence on the sorption behaviour. Asymmetrical shaped NPTs with broader size distribution seems to be mostly retained in the CGBs after longer equilibration time. This result shows the importance of the NPTs features on the mechanisms governing their transfer and fate in the environment through environmental matrices, especially when other materials are involved. We anticipate our work to be a starting point for investigating the co-transport of NPTs with other materials present in the environment (natural and anthropogenic).

5.
Chemosphere ; 255: 126912, 2020 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-32408126

RESUMEN

Nanoplastics (NPTs) are defined as colloids that originated from the unintentional degradation of plastic debris. To understand the possible risks caused by NPTs, it is crucial to determine how they are transported and where they may finally accumulate. Unfortunately, although most sources of plastic are land-based, risk assessments concerning NPTs in the terrestrial environmental system (soils, aquifers, freshwater sediments, etc.) have been largely lacking compared to studies concerning NPTs in the marine system. Furthermore, an important limitation of environmental fate studies is that the NPT models used are questionable in terms of their environmental representativeness. This study describes the fate of different NPT models in a porous media under unfavorable (repulsive) conditions, according to their physical and chemical properties: average hydrodynamic diameters (200-460 nm), composition (polystyrene with additives or primary polystyrene) and shape (spherical or polymorphic). NPTs that more closely mimic environmental NPTs present an inhomogeneous shape (i.e., deviating from a sphere) and are more deposited in a sand column by an order of magnitude. This deposition was attributed in part to physical retention, as confirmed by the straining that occurred for the larger size fractions. Additionally, different Derjaguin-Landau-Verwey-Overbeek (DLVO) models -the extended DLVO (XDLVO) and a DLVO modified by surface element integration (SEI) method-suggest that the environmentally relevant NPT models may alter its orientation to diminish repulsion from the sand surface and may find enough kinetic energy to deposit in the primary energetic minimum. These results point to the importance of choosing environmentally relevant NPT models.


Asunto(s)
Microplásticos/química , Modelos Químicos , Coloides , Agua Subterránea , Hidrodinámica , Modelos Teóricos , Porosidad , Arena
6.
Environ Sci Pollut Res Int ; 27(4): 3746-3755, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31044382

RESUMEN

Each year, 5 to 10 million tons of plastic waste is dumped in the oceans via freshwaters and accumulated in huge oceanic gyres. Under the effect of several abiotic factors, macro plastic wastes (or plastic wastes with macro sizes) are fractionated into microplastics (MP) and finally reach the nanometric size (nanoplastic NP). To reveal potential toxic impacts of these NPs, two microalgae, Scenedemus subspicatus (freshwater green algae), and Thalassiosira weissiflogii (marine diatom) were exposed for up to 48 h at 1, 10, 100, 1000, and 10,000 µg/L to reference polyethylene NPs (PER) or NPs made from polyethylene collected in the North Atlantic gyre (PEN, 7th continent expedition in 2015). Freshwater filter-feeding bivalves, Corbicula fluminea, were exposed to 1000 µg/L of PER and PEN for 48 h to study a possible modification of their filtration or digestion capacity. The results show that PER and PEN do not influence the cell growth of T. weissiflogii, but the PEN exposure causes growth inhibition of S. subspicatus for all exposure concentrations tested. This growth inhibition is enhanced for a higher concentration of PER or PEN (10,000 µg/L) in S. subspicatus. The marine diatom T. weissiflogii appears to be less impacted by plastic pollution than the green algae S. subspicatus for the exposure time. Exposure to NPs does not lead to any alteration of bivalve filtration; however, fecal and pseudo-fecal production increased after PEN exposure, suggesting the implementation of rejection mechanisms for inedible particles.


Asunto(s)
Microalgas , Polietileno/química , Contaminantes Químicos del Agua , Animales , Organismos Acuáticos , Océano Atlántico , Microalgas/química , Plásticos , Polietileno/análisis
7.
Environ Pollut ; 249: 940-948, 2019 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-30965546

RESUMEN

The nanoscale size of plastic debris makes them potential efficient vectors of many pollutants and more especially of metals. In order to evaluate this ability, nanoplastics were produced from microplastics collected on a beach exposed to the North Atlantic Gyre. The nanoplastics were characterized using multi-dimensional methods: asymmetrical flow field flow fractionation and dynamic light scattering coupled to several detectors. Lead (II) adsorption kinetics, isotherm and pH-edge were then carried out. The sorption reached a steady state after around 200 min. The maximum sorption capacity varied between 97% and 78.5% for both tested Pb concentrations. Lead (II) adsorption kinetics is controlled by chemical reactions with the nanoplastics surface and to a lesser extent by intraparticle diffusion. Adsorption isotherm modeling using Freundlich model demonstrated that NPG are strong adsorbents equivalent to hydrous ferric oxides such as ferrihydrite (log Kadsfreundlich=8.36 against 11.76 for NPG and ferrihydrite, respectively). The adsorption is dependent upon pH, in response to the Pb(II) adsorption by the oxygenated binding sites developed on account of the surface UV oxidation under environmental conditions. They could be able to compete with Fe or humic colloids for Pb binding regards to their amount and specific areas. Nanoplastics could therefore be efficient vectors of Pb and probably of many other metals as well in the environment.


Asunto(s)
Contaminantes Ambientales/análisis , Plomo/análisis , Nanopartículas/química , Plásticos/química , Contaminantes Químicos del Agua/análisis , Adsorción , Sitios de Unión , Compuestos Férricos/química , Fraccionamiento de Campo-Flujo , Francia , Concentración de Iones de Hidrógeno , Cinética , Modelos Teóricos , Propiedades de Superficie
8.
Environ Pollut ; 245: 371-379, 2019 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-30448507

RESUMEN

Plastic pollution in the marine environment poses threats to wildlife and habitats through varied mechanisms, among which are the transport and transfer to the food web of hazardous substances. Still, very little is known about the metal content of plastic debris and about sorption/desorption processes, especially with respect to weathering. In this study, plastic debris collected from the North Atlantic subtropical gyre was analyzed for trace metals; as a comparison, new packaging materials were also analyzed. Both the new items and plastic debris showed very scattered concentrations. The new items contained significant amounts of trace metals introduced as additives, but globally, metal concentrations were higher in the plastic debris. The results provide evidence that enhanced metal concentrations increase with the plastic state of oxidation for some elements, such as As, Ti, Ni, and Cd. Transmission electron microscopy showed the presence of mineral particles on the surface of the plastic debris. This work demonstrates that marine plastic debris carries complex mixtures of heavy metals. Such materials not only behave as a source of metals resulting from intrinsic plastic additives but also are able to concentrate metals from ocean water as mineral nanoparticles or adsorbed species.


Asunto(s)
Monitoreo del Ambiente/métodos , Metales Pesados/análisis , Plásticos/química , Oligoelementos/análisis , Residuos/análisis , Contaminantes Químicos del Agua/análisis , Océano Atlántico , Ecosistema , Expediciones , Clima Tropical , Tiempo (Meteorología)
9.
Anal Bioanal Chem ; 410(27): 6977-6984, 2018 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-30194453

RESUMEN

Applications of asymmetrical flow field-flow fractionation (AF4) continue to expand rapidly in the fields of nanotechnology and biotechnology. In particular, AF4 has proven valuable for the separation and analysis of particles, biomolecular species (e.g., proteins, bacteria) and polymers (natural and synthetic), ranging in size from a few nanometers to several micrometers. The separation of non-spheroidal structures (e.g., rods, tubes, etc.) with primary dimensions in the nanometer regime, is a particularly challenging application deserving of greater study and consideration. The goal of the present study was to advance current understanding of the mechanism of separation of rod-like nano-objects in the AF4 channel. To achieve this, we have systematically investigated a series of commercially available cetyltrimethylammonium bromide stabilized gold nanorods (AuNRs), with aspect ratios from 1.7 to 10. Results show clearly that the retention time is principally dependent on the translational diffusion coefficient of the AuNRs. Equations used to calculate translational and rotational diffusion coefficients (cylinder and prolate ellipsoid models) yield similarly good fits to experimental data. Well characterized gold nanorods (length and diameter by transmission electron microscopy) can be used as calibrants for AF4 measurements allowing one to determine the aspect ratio of nanorod samples based on their retention times. Graphical abstract ᅟ.


Asunto(s)
Fraccionamiento de Campo-Flujo/métodos , Oro/química , Nanotubos/química , Cetrimonio , Compuestos de Cetrimonio/química , Difusión , Hidrodinámica , Nanotubos/ultraestructura , Tamaño de la Partícula
10.
Environ Pollut ; 235: 1030-1034, 2018 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-29370948

RESUMEN

With the large amount of attention being given to microplastics in the environment, several researchers have begun to consider the fragmentation of plastics down to lower scales (i.e., the sub-micrometer scale). The term "nanoplastics" is still under debate, and different studies have set the upper size limit at either 1000 nm or 100 nm. The aim of the present work is to propose a definition of nanoplastics, based on our recently published and unpublished research definition of nanoplastics. We define nanoplastics as particles unintentionally produced (i.e. from the degradation and the manufacturing of the plastic objects) and presenting a colloidal behavior, within the size range from 1 to 1000 nm.


Asunto(s)
Nanopartículas/química , Plásticos/química , Contaminantes Químicos del Agua/química , Monitoreo del Ambiente , Nanopartículas/análisis , Plásticos/análisis , Terminología como Asunto , Contaminantes Químicos del Agua/análisis
11.
Chemosphere ; 194: 125-130, 2018 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-29197815

RESUMEN

Cigarette butts (CGB) are equivalent to plastic litter in terms of number of pieces released directly into the environment. Due to their small size and social use, CGB are commonly found in natural systems, and several questions have been raised concerning the contaminants that are released with CGB, including metals, organic species, and nanoparticles. The aim of the present study is to investigate the release of nanoscale particles from CGB by leaching with rainwater. After seven days of passive stirring of both smoked and unsmoked CGB in synthetic rainwater, the solutions were treated and analyzed by specific nano-analytical methods. Our results demonstrate the release of 4.12 ± 0.24% (w/CGB) organic carbon in the range of 10 nm up to 400 nm and with a z-average diameter of 202.4 ± 74.1 nm. The fractal dimension (Df) of the nanoscale particles ranges from 1.14 to 1.52 and suggests a soot (carbon)-based composition. The analysis of some metallic species (As, Pb, Cd, Cu, Ni, Cr, Co, Al, Mn, Zn, and Fe) shows that these species are essentially attached to the nanoscale particles per gram of carbon released. By considering the diffusion of the nanomaterials into different environmental compartments, our results suggest a new emerging and global contamination of the environment by cigarette butts, comparable to plastic litter, which urgently needs to be considered.


Asunto(s)
Monitoreo del Ambiente/métodos , Contaminación Ambiental , Nanopartículas/efectos adversos , Productos de Tabaco/efectos adversos , Carbono , Metales/análisis , Metales Pesados/análisis , Humo
12.
Environ Sci Technol ; 51(23): 13689-13697, 2017 Dec 05.
Artículo en Inglés | MEDLINE | ID: mdl-29161030

RESUMEN

Plastics can be found in all ecosystems across the globe. This type of environmental pollution is important, even if its impact is not fully understood. The presence of small plastic particles at the micro- and nanoscales is of growing concern, but nanoplastic has not yet been observed in natural samples. In this study, we examined four size fractions (meso-, large micro-, small micro-, and nanoplastics) of debris collected in the North Atlantic subtropical gyre. To obtain the nanoplastic portion, we isolated the colloidal fraction of seawater. After ultrafiltration, the occurrence of nanoscale particles was demonstrated using dynamic light scattering experiments. The chemical fingerprint of the colloids was obtained by pyrolysis coupled with gas chromatography-mass spectrometry. We demonstrated that the signal was anthropogenic and attributed to a combination of plastics. The polymer composition varied among the size classes. At the micro- and nanoscales, polyvinyl chloride, polyethylene terephthalate, polystyrene and polyethylene were observed. We also observed changes in the pyrolytic signals of polyethylene with decreasing debris size, which could be related to the structural modification of this plastic as a consequence of weathering.


Asunto(s)
Monitoreo del Ambiente , Plásticos , Polietileno , Poliestirenos , Agua de Mar
13.
Anal Bioanal Chem ; 409(29): 6761-6769, 2017 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-28948363

RESUMEN

In the last 10 years, asymmetrical flow field flow fractionation (AF4) has been one of the most promising approaches to characterize colloidal particles. Nevertheless, despite its potentialities, it is still considered a complex technique to set up, and the theory is difficult to apply for the characterization of complex samples containing submicron particles and nanoparticles. In the present work, we developed and propose a simple analytical strategy to rapidly determine the presence of several submicron populations in an unknown sample with one programmed AF4 method. To illustrate this method, we analyzed polystyrene particles and fullerene aggregates of size covering the whole colloidal size distribution. A global and fast AF4 method (method O) allowed us to screen the presence of particles with size ranging from 1 to 800 nm. By examination of the fractionating power F d, as proposed in the literature, convenient fractionation resolution was obtained for size ranging from 10 to 400 nm. The global F d values, as well as the steric inversion diameter, for the whole colloidal size distribution correspond to the predicted values obtained by model studies. On the basis of this method and without the channel components or mobile phase composition being changed, four isocratic subfraction methods were performed to achieve further high-resolution separation as a function of different size classes: 10-100 nm, 100-200 nm, 200-450 nm, and 450-800 nm in diameter. Finally, all the methods developed were applied in characterization of nanoplastics, which has received great attention in recent years. Graphical Absract Characterization of the nanoplastics by asymmetrical flow field flow fractionation within the colloidal size range.

14.
J Colloid Interface Sci ; 502: 193-200, 2017 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-28486140

RESUMEN

Fullerene (C60) aggregation mechanisms in aqueous media require considerable attention in the near future due to the heavy use and application of fullerene-based products within the context of nanotechnology. Such intensive development will result in the release of massive amounts of C60 in aqueous environmental systems in the aggregate form (nC60). In that sense, the aggregation mechanisms need to be fully determined to better evaluate the environmental fate and behavior of C60. To fulfil these needs, the aim of this work was to extensively characterize the aggregation mechanisms of fullerene aggregates in aqueous media by asymmetrical flow field fractionation (AF4) coupled to static light scattering (SLS). We developed a sequential ultrafiltration method that allows the fractionation of the whole nC60 size distribution into different size classes (1-100-200-450-800nm). Following a preliminary analysis by dynamic light scattering (DLS), we optimized several AF4 separation methods to allow screening of these colloidal size classes of nC60 with high efficiency and resolution. The fractal dimension (Df) of this entire size class was characterized directly on-line according to the radius of gyration through a combination of angle-dependent light scattering and fractal dimension analysis. We demonstrate the possible formation and persistence of colloidal populations of nC60 in aqueous media from a few nanometers up to 800nm. Df values ranging from 1.2 to 2.8, based on the nC60 colloidal size range, strongly depend on the method of the sample filtration.

15.
Anal Bioanal Chem ; 408(9): 2195-201, 2016 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-26873210

RESUMEN

The control of gold nanorod (GNR) solution-based syntheses has been hindered in part by the inability to examine and control the conversion of precursor seed populations to anisotropic materials, which have resulted in low yields of desired products and limited their commercial viability. The advantages offered by tandem separation and characterization methods utilizing asymmetric-flow field flow fractionation (A4F) are principally achieved as a result of their non-disruptive nature (minimizing artefacts), fast throughput, and in-situ analysis. With hyphenated A4F methods, resolved populations of seeds and secondary products, up to long aspect ratio rods, have been achieved and exemplify progress towards elucidating mechanistic aspects of formation and thus rational design. While there have been previously reported studies on A4F separation of GNRs, to our knowledge, this is the first published investigation of in situ GNR growth, separation, and characterization based on A4F, where its utilization in this capacity goes beyond traditional separation analysis. By using hydroquinone as the reducing agent, the conversion of the initial seed population to a distribution of products, including the GNRs, could be monitored in real time using A4F hyphenated with a diode array detector. Transmission electron microscopy confirms that the number of peaks observed during fractionation corresponds with size and shape dispersity. This proof-of-principle study introduces A4F as a technique that establishes a foundation for future mechanistic studies on the growth of GNRs from gold seeds, including conversion of the seed population to initial products, a topic highly relevant to advancing progress in nanomanufacturing.


Asunto(s)
Oro/química , Nanotubos , Fraccionamiento de Campo-Flujo , Microscopía Electrónica de Transmisión
16.
Langmuir ; 31(27): 7673-83, 2015 Jul 14.
Artículo en Inglés | MEDLINE | ID: mdl-26114747

RESUMEN

Cationic polyethylenimine conjugated gold nanoparticles (AuNP-PEI) are a widely studied vector for drug delivery and an effective probe for interrogating NP-cell interactions. However, an inconsistent body of literature currently exists regarding the reproducibility of physicochemical properties, colloidal stability, and efficacy for these species. To address this gap, we systematically examined the preparation, stability, and formation mechanism of PEI conjugates produced from citrate-capped AuNPs. We considered the dependence on relative molar mass, Mr, backbone conformation, and material source. The conjugation mechanism of Au-PEI was probed using attenuated total reflectance FTIR and X-ray photoelectron spectroscopy, revealing distinct fates for citrate when interacting with different PEI species. The differences in residual citrate, PEI properties, and sample preparation resulted in distinct products with differentiated stability. Overall, branched PEI (25 kDa) conjugates exhibited the greatest colloidal stability in all media tested. By contrast, linear PEI (25 kDa) induced agglomeration. Colloidal stability of the products was also observed to correlate with displaced citrate, which supports a glaring knowledge gap that has emerged regarding the role of this commonly used carboxylate species as a "place holder" for conjugation with ligands of broad functionalities. We observed an unexpected and previously unreported conversion of amine functional groups to quaternary ammonium species for 10 kDa branched conjugates. Results suggest that the AuNP surface catalyzes this conversion. The product is known to manifest distinct processes and uptake in biological systems compared to amines and may lead to unintentional toxicological consequences or decreased efficacy as delivery vectors. Overall, comprehensive physicochemical characterization (tandem spectroscopy methods combined with physical measurements) of the conjugation process provides a methodology for elucidating the contributing factors of colloidal stability and chemical functionality that likely influence the previously reported variations in conjugate properties and biological response models.


Asunto(s)
Oro/química , Nanopartículas del Metal/química , Modelos Biológicos , Polietileneimina/química , Coloides/química , Tamaño de la Partícula , Propiedades de Superficie
17.
Anal Chim Acta ; 819: 116-21, 2014 Mar 28.
Artículo en Inglés | MEDLINE | ID: mdl-24636419

RESUMEN

The aim of this work is to present a method based on asymmetric flow-field-flow-fractionation coupled on-line to a static light scattering (AF4-UV-SLS) detector to characterize self-assembled nanofibers (NFs). The method developed herein allows the determination of both the length distribution of the NFs as well as the distribution in terms of aggregation number per unit length (Agg). Given the remaining synthetic challenges of better controlling the structural homogeneity and particle dimensions, the NF length and aggregation number per unit length are becoming essential for the improvement and control of their chemical processes and a better understanding of their properties. The results obtained with this AF4-UV-SLS method indicate that a well-resolved NF length distribution characterization and Agg determination were attained. These results provide critical information concerning the physical properties of the investigated NFs and open the door to the characterization of new self-assembled polymers with various asymmetrical architectures.


Asunto(s)
Nanofibras/química , Polímeros/química , Suspensiones/análisis , Agua/química , Emulsiones/química , Polimerizacion , Polímeros/síntesis química
18.
Langmuir ; 30(13): 3883-93, 2014 Apr 08.
Artículo en Inglés | MEDLINE | ID: mdl-24625049

RESUMEN

We report the development of a novel cationic dendron (TAG1-PCD) and a positively charged gold nanoparticle-dendron conjugate (PCD-AuNP). TAG1-PCD was designed by considering the reactivity, hydrophilicity, and cationic nature that is required to yield a stable gold conjugate in aqueous media. The PCD-AuNPs, nominally 10 nm in size, were synthesized by reduction of chloroauric acid in the presence of TAG1-PCD. The physicochemical properties of PCD-AuNPs were characterized by dynamic light scattering, transmission electron microscopy, UV-vis absorbance, and X-ray photoelectron spectroscopy for investigation of size distribution, shape uniformity, surface plasmon resonance bands, and Au-dendron bonding. Asymmetric-flow field flow fractionation was employed to confirm the in situ size, purity, and surface properties of the PCD-AuNPs. Additionally, the stability of PCD-AuNPs was systematically evaluated with respect to shelf life determination, stability in biological media and a wide range of pH values, chemical resistance against cyanide, redispersibility from lyophilized state, and stability at temperatures relevant to biological systems. Dose dependent cell viability was evaluated in vitro using the human lung epithelial cell line A549 and a monkey kidney Vero cell line. Observations from in vitro studies are discussed. Overall, the investigation confirmed the successful development of stable PCD-AuNPs with excellent stability in biologically relevant test media containing proteins and electrolytes, and with a shelf life exceeding 6 months. The excellent aqueous stability and apparent lack of toxicity for this conjugate enhances its potential use as a test material for investigating interactions between positively charged NPs and biocellular and biomolecular systems, or as a vehicle for drug delivery.


Asunto(s)
Dendrímeros/química , Oro/química , Nanopartículas del Metal/química , Animales , Línea Celular Tumoral , Supervivencia Celular/efectos de los fármacos , Cloruros/química , Chlorocebus aethiops , Cianuros/química , Dendrímeros/farmacología , Portadores de Fármacos , Fraccionamiento de Campo-Flujo , Compuestos de Oro/química , Humanos , Interacciones Hidrofóbicas e Hidrofílicas , Nanopartículas del Metal/toxicidad , Nanopartículas del Metal/ultraestructura , Tamaño de la Partícula , Electricidad Estática , Propiedades de Superficie , Temperatura , Células Vero
19.
Anal Chim Acta ; 809: 9-24, 2014 Jan 27.
Artículo en Inglés | MEDLINE | ID: mdl-24418128

RESUMEN

This tutorial proposes a comprehensive and rational measurement strategy that provides specific guidance for the application of asymmetric-flow field flow fractionation (A4F) to the size-dependent separation and characterization of nanoscale particles (NPs) dispersed in aqueous media. A range of fractionation conditions are considered, and challenging applications, including industrially relevant materials (e.g., metal NPs, asymmetric NPs), are utilized in order to validate and illustrate this approach. We demonstrate that optimization is material dependent and that polystyrene NPs, widely used as a reference standard for retention calibration in A4F, in fact represent a class of materials with unique selectivity, recovery and optimal conditions for fractionation; thus use of these standards to calibrate retention for other materials must be validated a posteriori. We discuss the use and relevance of different detection modalities that can potentially yield multi-dimensional and complementary information on NP systems. We illustrate the fractionation of atomically precise nanoclusters, which are the lower limit of the nanoscale regime. Conversely, we address the upper size limit for normal mode elution in A4F. The protocol for A4F fractionation, including the methods described in the present work is proposed as a standardized strategy to realize interlaboratory comparability and to facilitate the selection and validation of material-specific measurement parameters and conditions. It is intended for both novice and advanced users of this measurement technology.

20.
Anal Bioanal Chem ; 406(6): 1651-9, 2014 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-24005603

RESUMEN

The development of highly efficient asymmetric-flow field flow fractionation (A4F) methodology for biocompatible PEGylated gold nanorods (GNR) without the need for surfactants in the mobile phase is presented. We report on the potential of A4F for rapid separation by evaluating the efficiency of functionalized surface coverage in terms of fractionation, retention time (t R ) shifts, and population analysis. By optimizing the fractionation conditions, we observed that the mechanism of separation for PEGylated GNRs by A4F is the same as that for CTAB stabilized GNRs (i.e., according to their AR) which confirms that the elution mechanism is not dependent on the surface charge of the analytes and/or the membrane. In addition, we demonstrated that A4F can distinguish different surface coverage populations of PEGylated GNRs. The data established that a change in Mw of the functional group and/or surface orientation can be detected and fractionated by A4F. The findings in this study provide the foundation for a complete separation and physicochemical analysis of GNRs and their surface coatings, which can provide accurate and reproducible characterization critical to advancing biomedical research.


Asunto(s)
Fraccionamiento de Campo-Flujo/métodos , Oro/química , Nanotubos/química , Polietilenglicoles/química , Diseño de Equipo , Fraccionamiento de Campo-Flujo/instrumentación , Tamaño de la Partícula , Espectrofotometría Ultravioleta , Propiedades de Superficie
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