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Titanium dioxide nanoparticles (TiO 2 NPs) are widely used in industry as a white pigment (paints, paper industry and toothpastes), photocatalysts (environmental decontamination and photovoltaic cells), inorganic UV filter (sunscreens and personal care products) and as a food additive (E171) and antimicrobial food packaging material. Silver nanoparticles (Ag NPs) are used in photonics, microelectronics, catalysis and medicine due to their catalytic activity, magnetic and optical polarizability, electrical and thermal conductivities and enhanced Raman scattering. They also have antibacterial, antifungal and antiviral activities, as well as anti-inflammatory potential. The huge increase in the use of nano-based products, mainly metallic NPs, implies the presence of nanomaterials in the environment, and hence, the unintentional human ingestion through water or foods (gastrointestinal tract is the main pathway of NPs intake in humans). The presence of TiO 2 NPs and Ag NPs in seafood samples was firstly established using an ultrasound assisted enzymatic hydrolysis procedure and sp-ICP-MS analysis. Several clams, cockles, mussels, razor clams, oysters and variegated scallops, which contain TiO 2 NPs and Ag NPs, were subjected to an in vitro digestion process simulating human gastrointestinal digestion in the stomach and in the small and large intestine to determine the bioaccessibility of these NPs. Caco-2 cells were selected as model of human intestinal epithelium for transport studies because of the development of membrane transporters that are responsible for the uptake of chemicals. Parameters as transepithelial electrical resistance (TEER) and permeability of Lucifer Yellow were studied for establishing cell monolayer integrity. TiO 2 NPs and Ag NPs transport as well as total Ti and Ag concentrations passing through the gastrointestinal epithelial barrier model (0-2 h) were assessed by sp-ICP-MS and ICP-MS in several molluscs., (Copyright © 2021 Elsevier B.V. All rights reserved.)

A method based on asymmetric flow field-flow fractionation (AF4) coupled to ultraviolet-visible (UV-vis) spectroscopy and inductively coupled plasma mass spectrometry (ICP-MS) has been developed for silver nanoparticles (Ag NPs) detection and quantification in bivalve molluscs. Samples were pre-treated using a conventional enzymatic (pancreatin and lipase) hydrolysis procedure (37 °C, 12 h). AF4 was performed using a regenerated cellulose (RC) membrane (10 kDa, 350 μm spacer) and aqueous 5 mM Tris-HCl pH = 7.4 as carrier. AF4 separation was achieved with a program that included a focusing step with tip and focus flows of 0.20 and 3.0 mL min -1 , respectively, and an injection time of 4.0 min. Elution of different size fractions was performed using a cross flow of 3.0 mL min -1 for 15 min, followed by linear cross flow decrease for 7.5 min, and a washing step for 9.4 min with no cross flow. Several bivalve molluscs (clams, oysters and variegated scallops) were analysed for total Ag content (ICP-MS after microwave assisted acid digestion), and for Ag NPs by the method presented here. Results show that Ag NPs are detected at the same elution time than proteins (UV monitoring at 280 and 405 nm), which suggests a certain interaction occurred between Ag NPs with proteins in the enzymatic extracts. AF4-UV-ICP-MS fractograms also suggest different Ag NPs size distributions for selected samples. Membrane recoveries, determined by peak area comparison of fractograms with and without application of cross flow, were within the 49-121% range. Confirmation of the presence Ag NPs in the investigated enzymatic extracts was demonstrated by SEM after an oxidative pre-treatment based on hydrogen peroxide and microwave irradiation., (Copyright © 2021 Elsevier B.V. All rights reserved.)

A reliable sample pre-treatment based on enzymatic hydrolysis has been fully optimized and validated for TiO 2 NPs isolation and determination/characterization in surimi (crab sticks). Efficient extractions have been found when using a pancreatin/lipase mixture at pH 7.4 and 37 °C for 12 h under continuous stirring. The proposed sample pre-treatment procedure has been found not to change TiO 2 NPs size distribution, therefore guaranteeing TiO 2 NPs integrity. TiO 2 NPs determination (TiO 2 NPs concentration) and TiO 2 NPs characterization (size distribution) were assessed by single-particle inductively coupled plasma mass spectrometry (sp-ICP-MS) working with dwell times in the microsecond range (high frequency of data acquisition). Method validation was performed for TiO 2 NPs concentrations and TiO 2 NPs sizes. Good repeatability (25% and 8% for TiO 2 NPs concentration and TiO 2 NPs most frequent size), and sensitivity (limit of detection of 5.28 × 10 5 NPs g -1 for TiO 2 NPs concentrations, and 31.3-37.1 nm for TiO 2 NPs size) were obtained. Accuracy, calculated through analytical recovery was adequate. Recoveries for TiO 2 NPs standards of 50 and 100 nm were 108 ± 5 and 105 ± 4%, respectively. The proposed methodology was applied to several surimi samples for assessing TiO 2 NPs concentrations and size distribution. Some surimi samples were found to contain TiO 2 NPs (concentrations from 1.40 × 10 7 to 1.19 × 10 9 NPs g -1 ). TiO 2 NPs size distributions were very different among the samples, and some of them showed wide size ranges (the most frequent size varied from 53.8 to 62.1 nm; whereas, the mean size values were within the 73.4-217.5 nm range)., (Copyright © 2018 Elsevier B.V. All rights reserved.)