1,721,089 research outputs found
Inorganic nanomaterials in food and consumer products
No full textIn the past two decades, a number of inorganic and organic nanomaterials (NMs) have been introduced into food, personal care, cosmetic and pharmaceutical applications, with the purpose of bringing a range of benefits to these sectors, mainly aiming at providing better quality and conservation.
The recent abundant use of NMs has placed, however, the accent on their potential risk, since nanoparticles, with their sizes between 1-100 nm, might interact with membrane cells of any living beings (plants, animals, humans). Consequently, legislators who are dealing with health and consumer protection have asked to the scientific community to implement or set-up new analytical methods able to detect and characterize the nanoparticles contained in food and consumer products in order to evaluate the risk on a solid definition of NMs.
This talk will illustrate, as the Field Flow Fractionation techniques (FFF), might be useful separation instruments to sort complex samples and to determine the average sizes and the particle size distribution of nano- and micro-particles. FFF techniques are often coupled online with a series of detectors such as UV-vis, refractive index, fluorescence, scattering detectors (DLS or MALS), ICP-MS, ICP-OES, GFAAS, whose choice depends on the practical application. Examples of SiO2, TiO2, silver, and ZnO separations will be presented in the light of the characterization required by the European Commission
Field flow fractionation techniques to explore the “nano-world”
No full textField flow fractionation (FFF) techniques are used to successfully characterize several nanomaterials by sizing nano-entities and producing information about the aggregation/agglomeration state of nanoparticles. By coupling FFF techniques to specific detectors, researchers can determine particle-size distributions (PSDs), expressed as mass-based or number-based PSDs. This review considers FFF applications in the food, biomedical, and environmental sectors, mostly drawn from the past 4 y. It thus underlines the prominent role of asymmetrical flow FFF within the FFF family. By concisely comparing FFF techniques with other techniques suitable for sizing nano-objects, the advantages and the disadvantages of these instruments become clear. A consideration of select recent publications illustrates the state of the art of some lesser-known FFF techniques and innovative instrumental set-ups
AN ORCHESTRA OF ANALYTICAL TECHNIQUES TO INVESTIGATE EVERYDAY PRODUCTS
No full textMany products of common use benefit of nanotechnologies. Cosmetic, sunscreen, pharmaceuticals, powdered food are only few examples of end products containing nano-sized particles (NPs), generally added to improve the product quality.
To evaluate correctly benefits versus risks of engineered nanomaterials, it would be necessary to well characterize the NPs as manufactured, as delivered for use in products, as present in the product matrix, as used in toxicity testing, and as present in biological fluids and tissues, this because, the physicochemical parameters might change in various environments.
On analytical point of view the identification, quantification and characterization of NPs in food matrices and in cosmetic or personal care products pose significant challenges, because NPs are usually present at low concentration levels and the matrices in which they are dispersed, are complexes and often incompatible with analytical instruments that would be required for their detection and characterization.
This presentation recalls some analytical techniques suitable for the detection, characterization and quantification of NPs in food and cosmetics products, and reports their recent application in characterizing specific metal and metal-oxide NPs in these two important industrial and market sectors
The sedimentation field flow fractionation technique to study the effects on PLGA particles of secondary preparative parameters and aging
No full textBiodegradable colloidal particles of PLGA (Poly(lactic-co-glycolic acid)) are excellent delivery carriers for drugs because they show high stability and high carrier capacity; they can feasibly incorporate both hydrophilic and hydrophobic substances, and offers various feasibly routes of administration. Several methods are currently employed to formulate PLGA particles with the smallest possible sizes and maximum stability for pharmaceutical applications
In this work PLGA particles were prepared by nanoprecipitation and single emulsion (or solvent evaporation) methods in order to achieve particles stable in the long run, with appropriate dimensions for injectable uses (200-400 nm size range).
Different concentrations of polymer and stabilizing (Pluronic® F68) were tested in order to identify the best conditions for making PLGA particles of suitable size, stable in time, that disperse themselves well in aqueous media, a key requirement for uses as vehicles to induce in vivo drug targeting, to be used as carriers for brain targeting drugs.
The particles with the best characteristics for delivery system design were those formulated by nanoprecipitation with an organic/water phase ratio of 2/30, a polymer concentration of 25 mg/mL and a surfactant concentration of 0.83 mg/mL; their surface charge was reasonably negative (~ -27 mV) and the average size of the almost monodisperse population was roughly 250 nm.
Particle characterization was accomplished by using SEM to check the morphology, calculating the surface charge through -potential measurements and determining the average sizes and particle size distributions (PSDs), the latter achieved by both PCS (photon correlation spectroscopy) and SdFFF (sedimentation field flow fractionation). SdFFF, the technique considered more reliable than PCS in describing the possible PSD modifications was used to investigate the effects three months of storage at 4 °C had on the lyophilized particles
Characterisation of TiO2 pigments in commercial foundation creams: a synergic use of the ICP-AES, square wave voltammetry and sedimentation FFF techniques
No full textA procedure to determine the presence of nano- or micro- TiO2 particles in commercial cosmetic formulations, which may have a daily use, is proposed. Two identificative techniques the Square Wave Voltammetry (SWV) and ICP-AES were employed to determine the amount of TiO2 in six foundation creams sold in Italy and USA. A new SWV method, based on an acidic digestion microwave-assisted of the sample, has been set up and the results were compared and critically commented with those obtained by the established ICP-AES method. The analytical procedure was verified by analyzing the P-25 Degussa sample. The sizes of the particles contained in the foundations were investigated through Sedimentation (SdFFF) and the Flow Field-Flow Fractionation (FlFFF) by analyzing aqueous slurries obtained from the foundation through a solvent extraction procedure. The FFF techniques sinergically coupled with the ICP-AES allowed to assess the sizes of the TiO2 particles. The content of the extracted slurries was also checked by TEM observations
Soft nanomaterials in the agrifood sector
No full textProducts based on nanotechnology or containing nanoparticles (NPs) are found in the entire food chain, from cultivation (agriculture), to the industrial processing and packaging of foods. Nanoscale materials can be naturally occurring, may be intentionally added or may be the result of unintentional contamination.
Intentionally added NPs are frequently used to improve taste, flavour, colour, texture, and consistency of foodstuffs, to increase absorption and bioavailability of nutraceuticals and health supplements, to develop food antimicrobials. Engineered nanomaterials result very useful also in food processing, food packaging, and storage include monitoring of food quality, safety, and biosecurity (for example, nanosensors for traceability and monitoring the condition of food during transport and storage).
By focusing the attention on the intentionally added NPs, their functionalities (e.g. release of food additives) depend on the physicochemical properties of NPs (size and size distribution, surface area, shape, solubility and dissolution, reactivity, coagulation or aggregation state, chemical composition, etc.) and on the biological matrices (compounds that are present in the matrix and thermodynamic conditions).
In this presentation, some examples of NPs used in the food chain are given, by distinguishing them between soft and hard nano-entities. Since the agricultural and food samples are heterogeneous systems, which may contain a mixture of natural and engineering NPs of different composition, their detection and characterization are usually very difficult and complex. In particular, nano-emulsions, micelles, nano-liposomes, solid lipid nanoparticles or nanostructured lipid carriers, biopolymers can be well characterised during their formulation by using many of the conventional analytical techniques (imaging, separation and spectroscopic techniques), but the sample pre-treatment necessary to reduce, for example the food matrix complexity, might introduce important alterations which make their in situ analysis sometimes almost impossible
FIELD FLOW FRACTIONATION: A WINDOW ON THE "nano-WORLD”
No full textThe term Field-Flow Fractionation (FFF) identifies a family of separation techniques able to separate sample components thanks to the action of a field force applied perpendicularly to a flow, which flows inside of an empty, thin and long channel. The different force field (liquid flows, centrifugal forces, temperature gradients or gravity fields), determines the FFF method.
FFF methods are suitable to separate both soluble and colloidal components over a wide size range, a feature, which make them particularly useful for the characterization of nano-entities, such the nanoparticles (NPs) added in many everyday products.
The most popular FFF method in the NPs characterization field is the FlowFFF (F4), often coupled on-line with specific element detectors, such as ICP-MS; equally suitable is the centrifugal FFF, which is actually more selective in term of sizes.
Size, in fact, along with shape, morphology and many other physicochemical parameters are the principal characteristics, which has to be determined to evaluate the health or/and environmental effects caused by the NPs.
This presentation summarizes the most relevant information, which can be determined with the FFF methods in the field of nanotechnologies
Introduction
No full textMany everyday products are manufactured using particulate materials whose behavior and performances depend upon starting particle chemical and structural characteristics.
Since particle characteristics affect the properties of a material, particle selection is normally needed across a range of industries and laboratories. Separation techniques play therefore a prominent role in selecting components to characterize them and for finding their possible useful applications.
This book presents an overview of some common separation techniques used to select and isolate particulate materials in liquid suspension, for a size chracterization or to prepare homogenous samples for a more detailed and complete physico-chemical characterization. The goal is to provide the Reader with the basic elements of these techniques for their conscious selection
Barley starch granules subject to SPLITT cell fractionation and Sd/StFFF size characterization
No full textThe coupling of two separation techniques is proposed as a methodology able to fractionate, starch granules of different botanical origins, both on preparative and analytical scale. The split flow thin cell (SPLITT cell) was optimized to produce a binary separation of the starch granules into two different size classes with a 5 mum cutoff point. The size separation was always better than 80%. The Sedimentation Steric Field Flow Fractionation (Sd/StFFF) provides sample particle size distribution (PSD) and is used here to control the SPLITT fractions. The proposed techniques, especially the former, are gentle and easy to use. Both the SPLITT and Sedimentation Fractionation results were checked by scanning electron microscopy (SEM). The procedure was originally applied to two samples from barley. The bimodal diameters were computed
A new strategy for pressed powder eye shadows analysis: Allergenic metal ions content and particle size distribution of the insoluble matter
No full textBefore being placed on the market, all cosmetics undergo a battery of safety tests to safeguard consumers from possible side-effects. Despite these controls, sometimes cosmetics do have side effects: some are immediate and visible reactions, others may appear with prolonged use.
Among decorative cosmetics, eye shadows deserve particular attention because they are applied in the peri-ocular area, the area around the eyes where the facial skin thinnest; here the risk of percutaneous absorption of the pigments — and thus of toxic elements — is very high as is the risk of developing irritative and/or allergic skin reactions.
In this work nine compact powder eye shadows — very inexpensive products sold in Italy and targeted to children and adults — were examined for the first time in order to i) determine the Ni, Co and Cr concentrations, ii) quantify the “water” soluble chromium and at the same time, iii) obtain the particle size distribution of the water-dispersible submicro-particles contained in all powders.
In many cases, the Cr, Co and Ni concentrations, determined by Graphite Furnace Atomic Absorption Spectrometry (GF-AAS), were higher than 1 or 5 ppm (μg/g), i.e. the limits recommended in the scientific literature to minimize the risk of reaction in particularly sensitive subjects. In most cases, the concentration of Cr was higher than that of Ni and Co, up to a limit case of 150 mg/g. In this particular sample, the potential amount of Cr that could be released in ionic form was determined in sweat simulating solutions by GF-AAS and confirmed through a specific spectrofluorimetric method; the results indicated the presence of approximately 80-90 ppb (ng/g) of Cr3+.
The water dispersible particles were isolated from the eye shadow powders through a simple solvent extraction procedure. The aqueous suspensions were then sorted through Sedimentation Field Flow Fractionation (SdFFF) and the particles sizes were calculated from experimental fractograms using theory. For the most part, the computed sizes were in the micron range, as confirmed by some SEM photographs taken on fractions collected during the separations. The SdFFF coupled off-line with the GFAAS enabled elemental characterization of pigment particles as a function of size.This finding reduces the concern that the ingredients of such makeup formulations may contain nanoparticles
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