In Vitro Assessment of the Physiologically Relevant Oral Bioaccessibility of Metallic Elements in Edible Herbs Using the Unified Bioaccessibility Protocol.

In this work, the total content of seven metallic elements (Fe, Cu, Zn, Mg, Pb, Ni, and Co) in common edible herbs was determined and related to their bioaccessibility by an in vitro human digestion model. Specifically, the unified bioaccessibility protocol developed by the BioAccessibility Research Group of Europe (BARGE) was used to determine the release of each element during gastric and gastrointestinal digestion. The results show that Fe, Zn, and Mg are released during gastric digestion (34-57% Fe, 28-80% Zn, 79-95% Mg), but their overall bioaccessibility is reduced in the gastrointestinal tract (<30%).

Development of a sequential extraction and speciation procedure for assessing the mobility and fractionation of metal nanoparticles in soils.

This study describes the development of a sequential extraction procedure for the evaluation of metal nanoparticle mobility and bioaccessibility in soils. The procedure, that was developed using gold nanoparticles (AuNPs) as model species, relies on the fractionation of nanoparticles by sequentially dissolving soil matrix components (carbonates, metal oxides, organic matter and mineral phases) in order to release the entrapped nanoparticle species in the extract solution. By summing up the concentration of AuNPs recovered in each fraction it was found that 93.

Determination of silver nanoparticles by atomic absorption spectrometry after dispersive suspended microextraction followed by oxidative dissolution back-extraction.

This study presents a liquid phase microextraction method for the quantification of silver nanoparticles (AgNPs) in environmental samples by means of directly suspended microextraction and atomic absorption spectrometry. The method is based on the dispersion of octanol into fine droplets where AgNPs are partitioned and extracted from the bulk aqueous phase. Then octanol is re-dispersed again in a strongly acidic and oxidizing aqueous medium in order to selectively decompose AgNPs to silver ions.

Intrinsic peroxidase-like activity of rhodium nanoparticles, and their application to the colorimetric determination of hydrogen peroxide and glucose.

The intrinsic peroxidase-like activity of rhodium nanoparticles (RhNPs) and their use as catalytic labels for sensitive colorimetric assays is presented. RhNPs catalyze the oxidation of the peroxidase substrate 3,3,5,5-tetramethylbenzidine (TMB) in the presence of HO to produce a blue reaction product with a maximum absorbance at 652 nm. Kinetic studies show catalysis to follow Michaelis-Menten kinetics and a "ping-pong" mechanism.

In-situ suspended aggregate microextraction of gold nanoparticles from water samples and determination by electrothermal atomic absorption spectrometry.

This work describes a new method for the extraction and determination of gold nanoparticles in environmental samples by means of in-situ suspended aggregate microextraction and electrothermal atomic absorption spectrometry. The method relies on the in-situ formation of a supramolecular aggregate phase through ion-association between a cationic surfactant and a benzene sulfonic acid derivative. Gold nanoparticles are physically entrapped into the aggregate phase which is separated from the bulk aqueous solution by vacuum filtration on the surface of a cellulose filter in the form of a thin film.

Paper-based assay of antioxidant activity using analyte-mediated on-paper nucleation of gold nanoparticles as colorimetric probes.

With the increasing interest in the health benefits arising from the consumption of dietary products rich in antioxidants, there exists a clear demand for easy-to-use and cost-effective tests that can be used for the identification of the antioxidant power of food products. Paper-based analytical devices constitute a remarkable platform for such expedient and low-cost assays with minimal external resources but efforts in this direction are still scarce. In this work we introduce a new paper-based device in the form of a sensor patch that enables the determination of antioxidant activity through analyte-driven on-paper formation of gold nanoparticles.