Assessing the Effect of Surface Coating on the Stability, Degradation, Toxicity and Cell Endocytosis/Exocytosis of Upconverting Nanoparticles

Lanthanide-doped up-converting nanoparticles (UCNPs) have emerged as promising biomedical tools in recent years. Most research efforts were devoted to the synthesis of inorganic cores with the optimal physicochemical properties. However, the careful design of UCNPs with the adequate surface coating to optimize their biological performance still remains a significant challenge. Here, we propose the functionalization of UCNPs with four distinct types of surface coatings, which were compared in terms of the provided colloidal stability and resistance to degradation in different biological-relevant media, including commonly avoided analysis in acidic lysosomal-mimicking fluids. Moreover, the influence of the type of particle surface coating on cell cytotoxicity and endocytosis/exocytosis was also evaluated. The obtained results demonstrated that the functionalization of UCNPs with poly(isobutylene-alt-maleic anhydride) grafted with dodecylamine (PMA-g-dodecyl) constitutes an outstanding strategy for their subsequent biomedical application, whereas poly(ethylene glycol) (PEG) coating, although suitable for colloidal stability purposes, hinders extensive cell internalization. Conversely, surface coating with small ligand were found not to be suitable, leading to large degradation degrees of UCNPs. The analysis of particle' behavior in different biological media and in vitro conditions here performed pretends to help researchers to improve the design and implementation of UCNPs as theranostic nanotools.

Detection of coca alkaloids in oral fluid from coca leaf (tea) consumers: using solid phase extraction to improve validation parameters and widen the detection window

Hygrine and cuscohygrine, two coca leaf alkaloids, have been previously proposed as markers to differentiate legal and illegal cocaine consumption. This is a very common problem in some countries of South America, where the consumption of coca leaves has a long tradition. Analytical methods focusing on the assessment of coca leaf alkaloids, such as cuscohygrine, hygrine, tropacocaine and t-cinnamoylcocaine, in oral fluid are virtually non-existent in forensic toxicology laboratories worldwide due to their lack of application. However, the problem of differentiating legal and illegal cocaine use in criminal justice, DUID (drug-impaired driving) and WDT (workplace drug testing) programs is growing. Therefore, researchers are obliged to develop methods to measure coca leaf alkaloids (cuscohygrine, hygrine and t-cinnamoylcocaine) in biological matrices for further validation for routine analyses in forensic toxicology laboratories. This work aims to optimize a previously published separation method by protein precipitation in oral fluid by using solid-phase extraction (SPE) coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) operating in multiple reaction monitoring (MRM) mode. The use of SPE allowed the matrix effect and the background to be reduced in the chromatograms due to the obtained cleaner extracts. Consequently, improved detection and quantification limits were reached. Findings showed that the detection windows for coca leaf alkaloids were longer than three hours in real oral fluid samples from volunteers who drank a cup of coca tea. These detection windows are quite higher than those previously obtained when using the method based on separation by protein precipitation.

Ultrasound assisted membrane-assisted solvent extraction for the simultaneous assessment of some drugs involved in drug-facilitated sexual assaults by liquid chromatography-tandem mass spectrometry

A simple and highly efficient ultrasound assisted membrane-assisted solvent extraction (MASE) pre-treatment method for urine has been developed and validated for the simultaneous determination of twenty-two drugs involved in drug-facilitated sexual assaults (DFSAs) by liquid chromatography-tandem mass spectrometry. MASE was performed with 4.0 mL of urine (pH adjusted at 12), 400 μL of hexane as an organic solvent inside the polypropylene membrane, and ultrasonication (45 kHz, 120 W) for 10 min. A pre-concentration factor of 40 was achieved after evaporation (N2 stream) and re-dissolution in 100 µL of methanol. Analytes were separated using a Zorbax Eclipse Plus C18 column under gradient elution with aqueous 10 mM NH4HCO3 (pH 8.0) and methanol as mobile phases. Matrix-matched calibrations allowed the assessment of DFSA drugs of quite different octanol-water partition coefficients (Ko/w), from 1.32 101 for pregabalin to 2.45 105 for clomipramine (Log P values from 1.12 (pregabalin) to 5.39 (clomipramine)). The limit of detection (LOD) was between 0.0075 to 0.37 µg L-1, with analytical recoveries ranging from 73 to 103%, and relative standard deviations (RSDs) within the 2-20% range. The applicability of the method was demonstrated after analysing urine samples under forensic investigation.

Acute Aquatic Toxicity to Zebrafish and Bioaccumulation in Marine Mussels of Antimony Tin Oxide Nanoparticles

Antimony tin oxide (Sb₂O₅/SnO₂) is effective in the absorption of infrared radiation for applications, such as skylights. As a nanoparticle (NP), it can be incorporated into films or sheets providing infrared radiation attenuation while allowing for a transparent final product. The acute toxicity exerted by commercial Sb₂O₅/SnO₂ (ATO) NPs was studied in adults and embryos of zebrafish (Danio rerio). Our results suggest that these NPs do not induce an acute toxicity in zebrafish, either adults or embryos. However, some sub-lethal parameters were altered: heart rate and spontaneous movements. Finally, the possible bioaccumulation of these NPs in the aquacultured marine mussel Mytilus sp. was studied. A quantitative analysis was performed using single particle inductively coupled plasma mass spectrometry (sp-ICP-MS). The results indicated that, despite being scarce (2.31 × 10⁶ ± 9.05 × 10⁵ NPs/g), there is some accumulation of the ATO NPs in the mussel. In conclusion, commercial ATO NPs seem to be quite innocuous to aquatic organisms; however, the fact that some of the developmental parameters in zebrafish embryos are altered should be considered for further investigation. More in-depth analysis of these NPs transformations in the digestive tract of humans is needed to assess whether their accumulation in mussels presents an actual risk to humans.

Quantitative titanium imaging in fish tissues exposed to titanium dioxide nanoparticles by laser ablation-inductively coupled plasma-mass spectrometry

Imaging studies by laser ablation-inductively coupled plasma mass spectrometry have been successfully developed to obtain qualitative and quantitative information on the presence/distribution of titanium (ionic titanium and/or titanium dioxide nanoparticles) in sea bream tissues (kidney, liver, and muscle) after exposure assays with 45-nm citrate-coated titanium dioxide nanoparticles. Laboratory-produced gelatine standards containing ionic titanium were used as a calibration strategy for obtaining laser ablation-based images using quantitative (titanium concentrations) data. The best calibration strategy consisted of using gelatine-based titanium standards (from 0.1 to 2.0 μg g^-1) by placing 5.0-μL drops of the liquid gelatine standards onto microscope glass sample holders. After air drying at room temperature good homogeneity of the placed drops was obtained, which led to good repeatability of measurements (calibration slope of 4.21 × 10⁴ ± 0.39 × 10⁴, n = 3) and good linearity (coefficient of determination higher than 0.990). Under the optimised conditions, a limit of detection of 0.087 μg g^-1 titanium was assessed. This strategy allowed to locate prominent areas of titanium in the tissues as well as to quantify the bioaccumulated titanium and a better understanding of titanium dioxide nanoparticle spatial distribution in sea bream tissues.

Bioaccumulation of titanium dioxide nanoparticles in green (Ulva sp.) and red (Palmaria palmata) seaweed

A bioaccumulation study in red (Palmaria palmata) and green (Ulva sp.) seaweed has been carried out after exposure to different concentrations of citrate-coated titanium dioxide nanoparticles (5 and 25 nm) for 28 days. The concentration of total titanium and the number and size of accumulated nanoparticles in the seaweeds has been determined throughout the study by inductively coupled plasma mass spectrometry (ICP-MS) and single particle-ICP-MS (SP-ICP-MS), respectively. Ammonia was used as a reaction gas to minimize the effect of the interferences in the 48Ti determination by ICP-MS. Titanium concentrations measured in Ulva sp. were higher than those found in Palmaria palmata for the same exposure conditions. The maximum concentration of titanium (61.96 ± 15.49 μg g-1) was found in Ulva sp. after 28 days of exposure to 1.0 mg L-1 of 5 nm TiO2NPs. The concentration and sizes of TiO2NPs determined by SP-ICP-MS in alkaline seaweed extracts were similar for both seaweeds exposed to 5 and 25 nm TiO2NPs, which indicates that probably the element is accumulated in Ulva sp. mainly as ionic titanium or nanoparticles smaller than the limit of detection in size (27 nm). The implementation of TiO2NPs in Ulva sp. was confirmed by electron microscopy (TEM/STEM) in combination with energy dispersive X-Ray analysis (EDX).

Single-cell ICP-MS for studying the association of inorganic nanoparticles with cell lines derived from aquaculture species

The current research deals with the use of single-cell inductively coupled plasma-mass spectrometry (scICP-MS) for the assessment of titanium dioxide nanoparticle (TiO₂ NP) and silver nanoparticle (Ag NP) associations in cell lines derived from aquaculture species (sea bass, sea bream, and clams). The optimization studies have considered the avoidance of high dissolved background, multi-cell peak coincidence, and possible spectral interferences. Optimum operating conditions were found when using a dwell time of 50 μs for silver and 100 μs for titanium. The assessment of associated TiO₂ NPs by scICP-MS required the use of ammonia as a reaction gas (flow rate at 0.75 mL min^-1) for interference-free titanium determinations (measurements at an m/z ratio of 131 from the ⁴⁸Ti(NH)(NH₃)₄ adduct). The influence of other parameters such as the number of washing cycles and the cell concentration on accurate determinations by scICP-MS was also fully investigated. Cell exposure trials were performed using PVP-Ag NPs (15 and 100 nm, nominal diameter) and citrate-TiO₂ NPs (5, 25, and 45 nm, nominal diameter) at nominal concentrations of 10 and 50 μg mL^-1 for citrate-TiO₂ NPs and 5.0 and 50 μg mL^-1 for PVP-Ag NPs. Results have shown that citrate-TiO₂ NPs interact with the outer cell membranes, being quite low in the number of citrate-TiO₂ NPs that enters the cells (the high degree of aggregation is the main factor which leads to the aggregates being in the extracellular medium). In contrast, PVP-Ag NPs have been found to enter the cells.

Isolation and quantification of synthetic cannabinoid receptor agonists in human urine using membrane-assisted solvent extraction followed by liquid chromatography-tandem mass spectrometry

The global market for new psychoactive substances (NPSs) continues to expand, and the range of drugs available on the market has probably never been wider. Synthetic cannabinoids (SCRAs) constitute the largest family of NPSs, and they go unnoticed during illicit drug market control and during routine toxicological-forensic analysis. Membrane-assisted solvent extraction (MASE) has been a novelty proposed for the simultaneous extraction of SCRAs, and urine has been selected as a model forensic-clinical sample. Isolated SCRAs were further determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS). An optimised sample pre-treatment procedure consists of using 400 μL of n-hexane as an extraction phase placed inside a polypropylene (PP) membrane, adjusting the donor phase (urine) at a pH value of 5.9. Extraction was assisted by mechanical (orbital-horizontal) stirring in a temperature-controlled chamber at room temperature for 20 min. n-Hexane extracts were evaporated to dryness and re-suspended in 100 μL of mobile phase, which leads to a pre-concentration factor of 50. Method validation showed analytical recoveries higher than 80% for most SCRAs and repeatability (inter-day and intra-day assays) with RSD values lower than 20%. The proposed method was found to be selective and sensitive and limits of quantification (LOQs) between 0.10 and 1.0 μg L^-1 were achieved.

Proteomics reveals multiple effects of titanium dioxide and silver nanoparticles in the metabolism of turbot, Scophthalmus maximus

Titanium dioxide (TiO₂) and silver (Ag) NPs are among the most used engineered inorganic nanoparticles (NPs); however, their potential effects to marine demersal fish species, are not fully understood. Therefore, this study aimed to assess the proteomic alterations induced by sub-lethal concentrations citrate-coated 25 nm ("P25") TiO₂ or polyvinylpyrrolidone (PVP) coated 15 nm Ag NPs to turbot, Scophthalmus maximus. Juvenile fish were exposed to the NPs through daily feeding for 14 days. The tested concentrations were 0, 0.75 or 1.5 mg of each NPs per kg of fish per day. The determination of NPs, Titanium and Ag levels (sp-ICP-MS/ICP-MS) and histological alterations (Transmission Electron Microscopy) supported proteomic analysis performed in the liver and kidney. Proteomic sample preparation procedure (SP3) was followed by LC-MS/MS. Label-free MS quantification methods were employed to assess differences in protein expression. Functional analysis was performed using STRING web-tool. KEGG Gene Ontology suggested terms were discussed and potential biomarkers of exposure were proposed. Overall, data shows that liver accumulated more elements than kidney, presented more histological alterations (lipid droplets counts and size) and proteomic alterations. The Differentially Expressed Proteins (DEPs) were higher in Ag NPs trial. The functional analysis revealed that both NPs caused enrichment of proteins related to generic processes (metabolic pathways). Ag NPs also affected protein synthesis and nucleic acid transcription, among other processes. Proteins related to thyroid hormone transport (Serpina7) and calcium ion binding (FAT2) were suggested as biomarkers of TiO₂ NPs in liver. For Ag NPs, in kidney (and at a lower degree in liver) proteins related with metabolic activity, metabolism of exogenous substances and oxidative stress (e.g.: NADH dehydrogenase and Cytochrome P450) were suggested as potential biomarkers. Data suggests adverse effects in turbot after medium/long-term exposures and the need for additional studies to validate specific biological applications of these NPs.

Semiconductor Quantum Dots as Target Analytes: Properties, Surface Chemistry and Detection

Since the discovery of Quantum Dots (QDs) by Alexey I. Ekimov in 1981, the interest of researchers in that particular type of nanomaterials (NMs) with unique optical and electrical properties has been increasing year by year. Thus, since 2009, the number of scientific articles published on this topic has not been less than a thousand a year. The increasing use of QDs due to their biomedical, pharmaceutical, biological, photovoltaics or computing applications, as well as many other high-tech uses such as for displays and solid-state lighting (SSL), has given rise to a considerable number of studies about its potential toxicity. However, there are a really low number of reported studies on the detection and quantification of QDs, and these include ICP–MS and electrochemical analysis, which are the most common quantification techniques employed for this purpose. The knowledge of chemical phenomena occurring on the surface of QDs is crucial for understanding the interactions of QDs with species dissolved in the dispersion medium, while it paves the way for a widespread use of chemosensors to facilitate its detection. Keeping in mind both human health and environmental risks of QDs as well as the scarcity of analytical techniques and methodological approaches for their detection, the adaptation of existing techniques and methods used with other NMs appears necessary. In order to provide a multidisciplinary perspective on QD detection, this review focused on three interrelated key aspects of QDs: properties, surface chemistry and detection.

Metal Content in Textile and (Nano)Textile Products

Metals, metallic compounds, and, recently, metallic nanoparticles appear in textiles due to impurities from raw materials, contamination during the manufacturing process, and/or their deliberate addition. However, the presence of lead, cadmium, chromium (VI), arsenic, mercury, and dioctyltin in textile products is regulated in Europe (Regulation 1907/2006). Metal determination in fabrics was performed by inductively coupled plasma-mass spectrometry (ICP-MS) after microwave-assisted acid digestion. The ICP-MS procedure has been successfully validated; relative standard deviations were up to 3% and analytical recoveries were within the 90-107% range. The developed method was applied to several commercial textiles, and special attention has been focused on textiles with nanofinishing (fabrics prepared with metallic nanoparticles for providing certain functionalities). Arsenic content (in textile T4) and lead content (in subsamples T1-1, T1-2, and T3-3) were found to exceed the maximum limits established by the European Regulation 1907/2006. Although impregnation of yarns with mercury compounds is not allowed, mercury was quantified in fabrics T1-2, T5, and T6. Further speciation studies for determining hexavalent chromium species in sample T9 are necessary (hexavalent chromium is the only species of chromium regulated). Some textile products commercialised in Europe included in this study do not comply with European regulation 1907/2006.

Titanium dioxide nanoparticles assessment in seaweeds by single particle inductively coupled plasma - Mass spectrometry

In this study, a first attempt for isolating and determining (characterising) background levels of titanium dioxide nanoparticles (TiO₂ NPs) in seaweed has been developed by using single particle inductively coupled plasma - mass spectrometry (SP-ICP-MS). Seaweeds were processed using an optimised ultrasound assisted extraction (UAE) procedure based on tetramethylammonium hydroxide (TMAH) before dilution and SP-ICP-MS analysis. The effect of the TMAH percentage in the extracting solution, as well as the volume of extracting solution and sonication (extraction) time, has been fully assessed. Additional experiments also showed that TiO₂ NPs were quantitatively released from the seaweed matrix in one UAE step since the analysis of residues gave TiO₂ NPs concentrations lower than the limit of quantification (LOQ) of the method. Validation of the method with 50 and 100 nm TiO₂ NPs (10 μg L^-1 as Ti) showed good analytical recovery (115% and 112% for 50 and 100 nm TiO₂ NPs, respectively), and good reproducibility (2% for size and 16% for number of TiO₂ NPs). Experiments regarding TiO₂ NPs stability showed that the extracted NPs are stable since there were not changes on the number of TiO₂ NPs and TiO₂ NPs size distributions when exposing TiO₂ NPs standards to the optimised extractive conditions.

Determination of the Trace Element Contents of Fruit Juice Samples by ICP OES and ICP-MS

Fruit juices were analysed for their contents in a series of essential and toxic elements (Al, As, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Na, Ni, Pb, V, Sb, Mo and Zn). Samples were subjected to microwave-assisted acid digestion (HNO3/H2O2), and analytes were determined by inductively coupled plasma optical emission spectrometry (ICP-OES), in axial mode, or by inductively coupled plasma mass spectrometry (ICP-MS), with kinetic energy discrimination, using 103Rh and 89Y as internal standards. The methods were validated, showing good precision (relative standard deviations < 10%), linearity and mean analytical recovery values (89 to 103%). The ICP-OES instrumental limits of detection (LODs) were between 0.3 μg L-1 (for Mg) and 1.5 μg L-1 (for Ca), whereas ICP-MS instrumental LODs varied from 2 ng L-1 (for Co, Mo and V) to 5.7 μg L-1 (for Na). Some toxic elements (As and Sb) were not detected in the fruit juices analyzed, Cd concentrations were below the maximum permitted level established by Brazilian and European regulations and only in one sample the Pb concentration (61.7 µg L-1) exceeded current legal limits. Besides, essential elements such as Ca, Mg and Na were in high concentrations in the samples analyzed.

Bioavailability of Aflatoxins in Cultured Fish and Animal Livers Using an In Vitro Dialyzability Approach

The objective of the present study was to investigate the bioavailability of aflatoxins (AFs) from fish, and chicken and rabbit livers using an in vitro dialyzability approach. Ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was used to assess the aflatoxin content in samples, as well as in dialyzate and residue fractions after the in vitro procedure. A vortex-assisted dispersive liquid-liquid microextraction (VALLME) technique was used for preconcentrating AFs before determination. Raw samples showed bioavailability ratios of 41-45% for aflatoxin B1 (AFB1), 28-38% for aflatoxin B2 (AFB2), and 42% for aflatoxin G2 (AFG2). Aflatoxin G1 (AFG1) was not detected. The culinary process (steaming or grilling) was found to change AFs' bioavailability (higher bioavailability ratios were found in cooked samples). AFB2 was found to be transformed into other compounds during the in vitro process, and the presence of AFB2 and AFB2 transformation/degradation products was investigated and confirmed by high-resolution mass spectrometry (HRMS).

AF4-UV-ICP-MS for detection and quantification of silver nanoparticles in seafood after enzymatic hydrolysis

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.

Assessment of trace levels of aflatoxins AFB1 and AFB2 in non-dairy beverages by molecularly imprinted polymer based micro solid-phase extraction and liquid chromatography-tandem mass spectrometry

A selective molecularly imprinted polymer (MIP) adsorbent was synthesised and used in a batch micro-solid phase extraction format for isolating aflatoxins (AFB1, and AFB2) from non-dairy beverages before liquid chromatography-tandem mass spectrometry determination. MIP synthesis (precipitation polymerization in 3 : 1 acetonitrile/toluene as a porogen) was performed with 5,7-dimethoxycoumarin (DMC), methacrylic acid (MAA) and divinylbenzene-80 (DVB) as a dummy template, functional monomer and cross-linker, respectively (1 : 4 : 20 molar ratio). 2,2'-Azobisisobutyronitrile (AIBN) was used as a polymerization initiator. The adsorbent MIP (50 mg) was enclosed in a cone-shaped polypropylene membrane (porous membrane protected molecularly imprinted micro-solid phase extraction), and parameters such as sample pH, mechanical (orbital-horizontal) shaking, the extraction time (loading stage), the composition of the eluting solution, and the desorption time were optimised. The highest extraction yields were obtained by using 5 mL of non-dairy beverages (pH adjusted at 6.0), and mechanical shaking (150 rpm) for 15 min. Elution was performed with 5 mL of an acetonitrile/formic acid (97.5 : 2.5) mixture under ultrasound (325 W, 35 kHz) for 15 min. After eluate evaporation to dryness and re-dissolution in 150 μL of the mobile phase, the pre-concentration factor of the method was 33.3, which yields limits of detection within the 0.085-0.207 μg L^-1 range. In addition, the current proposal was shown to be an accurate and precise method through relative standard deviation of intraday and inter-day assays below 18% and analytical recoveries in the range of 91-104%. However, the method was found to suffer from matrix effects.

Human Milk Concentrations of Minerals, Essential and Toxic Trace Elements and Association with Selective Medical, Social, Demographic and Environmental Factors

This study aims to quantify concentrations of minerals and trace elements in human milk (HM) and infant formula (IF) and evaluate associations with medical, social, environmental, and demographic variables. A prospective, case series study of 170 nursing mothers was made. HM samples were obtained from full-term (colostrum, intermediate and mature HM) and preterm (mature HM) mothers. Variables of interest were assessed by a questionnaire. For comparison, IF samples (n = 30) were analyzed in a cross-sectional study. Concentrations of 35 minerals, essential and toxic trace elements were quantified, 5 for the first time: thallium in HM and IF; strontium in preterm HM; and gallium, lithium and uranium in IF. In preterm and full-term HM, levels of selenium (p < 0.001) were significantly lower than recommended and were associated with low birth weight (p < 0.002). Cesium and strontium concentrations were significantly higher than recommended (p < 0.001). Associations were observed between arsenic and residence in an urban area (p = 0.013), and between lead and smoking (p = 0.024) and well-water consumption (p = 0.046). In IF, aluminum, vanadium, and uranium levels were higher than in HM (p < 0.001); uranium, quantified for the first time, was 100 times higher in all types of IF than in HM. Our results indicate that concentrations of most trace elements were within internationally accepted ranges for HM and IF. However, preterm infants are at increased risk of nutritional deficiencies and toxicity. IF manufacturers should reduce the content of toxic trace elements.

Caco-2 in vitro model of human gastrointestinal tract for studying the absorption of titanium dioxide and silver nanoparticles from seafood

Titanium dioxide nanoparticles (TiO₂ 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 TiO₂ 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 TiO₂ 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. TiO₂ 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.

Biopersistence rate of metallic nanoparticles in the gastro-intestinal human tract (stage 0 of the EFSA guidance for nanomaterials risk assessment)

The European Food Safety Authority has published a guidance regarding risk assessment of nanomaterials in food and feed. Following these recommendations, an in vitro gastrointestinal digestion has been applied to study the biopersistence of TiO₂ and Ag NPs in standards, molluscs and surimi. TiO₂ NPs standards and TiO₂ NPs/ TiO₂ microparticles from E171 were not found to be degraded. Ag NPs proved to be more degradable than TiO₂ NPs, but the biopersistence rates were higher than 12%, which means that Ag NPs are also biopersistent. Findings for seafood are quite similar to those obtained for TiO₂ NPs and Ag NPs standards, although the calculation of the biopersistence rate proposed by the EFSA was not found to be straightforward for foodstuff (the use of the NPs concentration in the sample instead of the NPs concentration at initial time (sample mixed with the gastric solution before enzymatic hydrolysis) has been proposed.

Trace elements in dried blood spots as potential discriminating features for metabolic disorder diagnosis in newborns

Trace elements in dried blood spots (DBSs) from newborns were determined by laser ablation coupled with inductively coupled plasma mass spectrometry, and data were subjected to chemometric evaluation in an attempt to classify healthy newborns and newborns suffering from metabolic disorders. Unsupervised [principal component analysis (PCA) and cluster analysis (CA)] and supervised [linear discriminant analysis (LDA) and soft independent modeling by class analogy (SIMCA)] pattern recognition techniques were used as classification techniques. PCA and CA have shown a clear tendency to form two groups (healthy newborns and newborns suffering from metabolic disorders). LDA and SIMCA have predicted that 90.5% and 83.9% of originally grouped healthy newborn cases were correctly classified by LDA and SIMCA, respectively. In addition, these percentages were 97.6% (LDA) and 80.6% (SIMCA) for DBSs from newborns suffering from metabolic disorders. However, SIMCA has only detected one misclassified DBS from the healthy group, and the lower percentage is attributed to four DBSs from the healthy newborn group and five DBSs from newborns with disorders that were found as belonging to both categories (healthy newborns and newborns with disorders) in the training set. LDA also gave a percentage of grouped maple syrup urine disease (MSUD) cases correctly classified of 100%, although the percentage fells to 66.7% when classifying phenylketonuria (PKU) cases. Finally, essential elements such as Fe, K, Rb, and Zn were found to be matched (correlated) with the concentration of amino acids such as phenylalanine, valine, and leucine, biomarkers linked with MSUD and PKU diseases.

Mercury speciation in edible seaweed by liquid chromatography - Inductively coupled plasma mass spectrometry after ionic imprinted polymer-solid phase extraction

In contrast to most of essential and heavy metals, mercury levels in seaweed are very low, and pre-concentration methods are required for an adequate total mercury determination and mercury speciation in this foodstuff. An ionic imprinted polymer-based solid phase extraction (on column) pre-concentration procedure has been optimized for mercury species enrichment before liquid chromatography hyphenated with inductively coupled plasma mass spectrometry determination. The polymer has been synthesized by the precipitation polymerization method and using a ternary pre-polymerization mixture containing the template (methylmercury), a non-vinylated monomer (phenobarbital), and a vinylated monomer (methacrylic acid). Factors affecting the adsorption/desorption of Hg species (extract pH, loading and elution flow rates, volume of eluent, etc.), and parameters such as breakthrough volume and reusability, were fully studied. Mercury species were first isolated from seaweed by ultrasound assisted extraction using a 0.1% (v/v) HCl, 0.12% (w/v) l-cysteine, 0.1% (v/v) mercaptoethanol solution. Under optimized conditions, the limits of detection were 0.007 and 0.02 μg kg^-1 dw for methylmercury and Hg(II), respectively. The pre-concentration factor (volume of 10 mL of seaweed extract) was 50. Repeatability and reproducibility of the method were satisfactory with relative standard deviations lower than 16%. The proposed methodology was finally applied for the selective pre-concentration and determination of methylmercury and Hg (II) in a BCR-463 certified reference material and in several edible seaweeds.

Miniaturized vortex assisted-dispersive molecularly imprinted polymer micro-solid phase extraction and HPLC-MS/MS for assessing trace aflatoxins in cultured fish

A dispersive micro-solid phase extraction approach using a molecularly imprinted polymer as an adsorbent has been developed for pre-concentrating aflatoxins from cultured fish. Aflatoxins were first isolated from fish muscle and liver by an ultrasound assisted extraction procedure using a 60 : 40 acetonitrile/0.1 M KH2PO4 aqueous buffer (pH 6.0) mixture. Polymeric adsorbent beads were synthesized using 5,7-dimethoxycoumarin as a dummy template, methacrylic acid as a functional monomer, divinylbenzene as a crosslinker, and 2,2'-azobisisobutyronitrile as an initiator. Parameters affecting the steps of extraction procedure, including the sample (fish extract) pH, adsorption stirring speed and time, desorption stirring speed and time, elution solvent ratio, and polymer capacity, were investigated and optimized. The limit of detection was found to vary from 0.29 to 0.61 μg kg-1 for the several aflatoxins. The proposed method was shown to be accurate and precise. Intraday and inter-day relative standard deviations were lower than 20%, and intraday and inter-day analytical recoveries were within the 80-100% range. The prepared adsorbent in the dispersive micro-solid phase extraction format was re-usable, and the pre-concentration procedure was found to be simple, rapid and highly selective and sensitive to identify/quantify AFs in fish.

Development of a sensitive method for the analysis of four phthalates in tea samples: Tea bag contribution to the total amount in tea infusion

A sensitive, precise and selective method for the analysis of butyl benzyl phthalate (BBP), diethyl phthalate (DEP), dibutyl phthalate (DBP), and dimethyl phthalate (DMP) in tea samples has been applied. Molecularly Imprinted Polymer-Solid Phase Extraction (MIP-SPE) has been used for the separation and preconcentration of these compounds. Phthalates extracted by SPE were analysed by high-performance liquid chromatography-electrospray ionisation-mass spectrometry (HPLC-ESI-MS). The method was sensitive (LOD < 2 µg L^-1), precise (RSD <10%) and accurate with recovery percentages ranging from 84% to 97%. Finally, the developed method was applied for the analysis of these phthalates in several tea samples marketed in bags. Migration studies were also performed to evaluate the concentration of phthalates released from the bags into the infusions, and teabag filters were analysed by Fourier-transform infrared spectroscopy. The migration study shows that tea filter bags contribute to the total phthalates concentration in tea infusion, and this contribution varies between 1.8 to 93.5 % of the total phthalates' concentrations. Tea filter bags release higher DBP than BBP, DMP, and DEP.

The bioavailability of arsenic species in rice

Rice is the principal food in many countries for billions of people and one of the most consumed cereals in the world. The rice plant has the ability to bioaccumulate essential and toxic trace elements such as arsenic. The toxicity of the elements depends not only on their concentration but also on their chemical form and their bioavailability. The inorganic forms of arsenic are more toxic than the organic forms and the toxicity increases with decreasing oxidation states. The consumers of rice in Europe who are the most exposed to inorganic arsenic are children under three, thorough diet (rice-based food). Recently, the European Commission established the maximum levels of inorganic arsenic in foodstuffs. This regulation establishes a maximum level of inorganic arsenic of 100 μg kg^-1 in rice destined for the production of food for infants and young children. In order to know the relation between the As ingested and the arsenic absorbed, studies of bioavailability are necessary. We proposed an in vitro digestion method with dialysis to estimate this relation. Furthermore, a bioavailability study of As species in rice was performed in order to know if a change in As species occurred during the gastrointestinal digestion process. Arsenic species were determined in rice and in the dialysate fraction by high-performance liquid chromatography coupled to inductively coupled plasma mass spectrometry (HPLC-ICP-MS). The proposed method has been applied to different rice samples acquired in the local Spanish market. Graphical abstract.

Ionic imprinted polymer solid-phase extraction for inorganic arsenic selective pre-concentration in fishery products before high-performance liquid chromatography - inductively coupled plasma-mass spectrometry speciation

Low levels of inorganic arsenic [As(III) and As(V)] in fishery products have been selectively isolated from fish extracts (1.0 g of wet fish samples pre-treated with 10 mL of 1:1 methanol/water under sonication at 25 °C for 30 min) by ionic imprinted polymer (IIPs) based solid phase extraction procedure (on-column mode). The selective adsorbent was synthesized using sodium (meta) arsenite as a template, 1-vinyl imidazole as a functional monomer, divinylbenzene as a cross-linker, and 2,2'-azobisisobutyronitrile as an initiator. Optimized pre-concentration conditions imply fish extract (10 mL) pH adjustment at 8.5 before loading (flow rate of 0.25 mL min^-1), and elution with ultrapure water (2 mL) at 0.50 mL min^-1. A pre-concentration factor of 50 was finally obtained after evaporation to dryness (N₂ stream) and re-dissolution in 0.2 mL of ultrapure water before HPLC-ICP-MS. Synthesized material was found to pre-concentrate inorganic arsenic species; whereas organic arsenic compounds, mainly arsenobetaine (the major organoarsenic compound in fish/seafood products), were not found to interact with the adsorbent. The developed selective method gave limits of quantification of 1.05 and 1.31 µg kg^-1 for As (III) and As (V), respectively, and good precision [relative standard deviations lower than 12% in fish extracts spiked at several As (III) and As (V) levels]. The proposed method was finally applied to the selective determination of As (III) and As (V) species in several fishery products.

Discrete sampling based-flow injection as an introduction system in ICP-MS for the direct analysis of low volume human serum samples

Discrete sampling based on the flow injection options offered by advanced autosamplers has been tested and applied for the direct analysis of low volume samples (human serum) for multi-elemental purposes (simultaneous Al, Be, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Mo, Ni, Pb, Rb, Se, V, and Zn assessment). Serum samples (200 µL aliquots) were directly diluted to 2.0 mL with 1% (v/v) HNO₃, and discrete sampling operating conditions were optimized to allow cleaning, loading (300 µL injection loop), and measuring steps by using a volume lower than 2.0 mL (diluted serum sample). Matrix effect has been overcome by using the standard addition technique, and accurate results implied the use of kinetic energy discrimination (KED) mode (He as a collision gas) for measurements. The proposed method has been found to be reliable for serum samples analysis because of the low sample volume requirements, the minimal sample preparation required, and high sampling rate (each replicate analysis takes 2.50 min). In addition, validation results show good precision and accuracy (both analytical recovery and analysis of certified reference materials), and acceptable sensitivity. Applicability of the proposed method has been finally demonstrated by analysing several serum samples from healthy adults.

Possibilities of single particle-ICP-MS for determining/characterizing titanium dioxide and silver nanoparticles in human urine

OBJECTIVE

The current use of nanoparticles in personal care and cosmetics, food safety, agriculture, medicine and pharmacy has led to a growing concern on the toxicity of these emerging materials to humans and also to the environment. Nanoparticles assessment (determination and size distribution) is a challenge mainly due to limitations of the current analytical instrumentation, but also because nanoparticles in foodstuff and environmental samples are usually found at low concentrations. The scenario is even more critical when dealing with clinical samples, mainly when trying to assess nanoparticles at basal levels in complex samples such as blood and urine. The aim of this paper is to find data regarding the presence of nanoparticles at basal levels in urine human samples.

METHODS

The use of single particle - inductively couple plasma - mass spectrometry (sp-ICP-MS) has been explored to determine and characterize silver and titanium dioxide nanoparticles in human urine. Urine samples were directly diluted (1:5 to 1:10) with 1%(v/v) glycerol before sp-ICP-MS measurements, and efforts were made for validating the over-all procedure.

RESULTS

The limit of detection and quantification for Ag NPs were 5.72 × 10³ and 1.91 × 10⁴ Ag NPs mL^-1, respectively; whereas, values for TiO₂ NP concentrations were 4.31 × 10³ and 1.44 × 10₄ TiO₂ NPs mL^-1. The limit of detection in size after applying several methods (3σ/5σ criteria) was found to be within the 8-9 nm for Ag NPs, and from 15 to 18 nm for TiO₂ NPs. Within-batch precision for Ag NP concentration was 15% (11% for mean size of nanoparticle distributions). Repeatability for TiO₂ NPs was 25% (TiO₂ NP concentration) and 9% (TiO₂ NP mean size). Good analytical recovery rates were found for spiked experiments with Ag NP standards of 40 and 60 nm (values within the 104-106% range), and also for TiO₂ NPs of 50 and 100 nm (96-98%). Finally, basal levels of Ag NPs and TiO₂ NPs, as well as total Ag and Ti concentrations, in human urine were assessed. Low Ag and Ag NP concentrations were found. Ag NPs exhibited mean sizes of approximately 16-17 nm. Total Ti levels, however, were higher than total Ag concentration, and TiO₂ NP concentrations within the 1.56 × 10⁴-2.80 × 10⁴ NPs mL^-1 range were measured (TiO₂ NP mean sizes were from 76 to 98 nm).

Development of a Reliable Method for Assessing Coca Alkaloids in Oral Fluid by HPLC-MS-MS

A reliable method based on high-performance liquid chromatography-tandem mass spectrometry has been developed for the assessment of coca alkaloids/metabolites [cocaine (COC), benzoylecgonine (BE), cocaethylene (CE), ecgonine methyl ester (EME), anhydroecgonine methyl ester (AEME), tropococaine (TRO), transcinnamoylcocaine (trCIN), cuscohygrine (CUS) and hygrine (HYG)] in oral fluid samples from cocaine abusers and from coca leaves consumers (coca leaves chewers and coca tea drinkers). Oral fluid samples were collected by the passive drool technique (spitting), and after centrifugation the supernatant was treated for protein removal by adding acidified acetonitrile. The developed method was fully validated according to the international criteria and good results have been obtained (intraday and inter-day precisions were lower than ±20%, intraday and inter day accuracy was within the 75-116% range, and LODs/LOQs was lower and close to cut-off values for COC and BE). The proposed method has been successfully applied to oral fluid samples from cocaine abusers, and also from coca leave chewers and coca tea drinkers. CUS and HYG were only found in oral fluid from people who chewed coca leaves and drank coca tea and were not detected in cocaine abusers. Both CUS and HYG could be good markers in oral fluid for distinguishing people who consume coca leaves legally (coca leave chewers and coca tea drinkers) from those who consume illegal cocaine.

HPLC-MS/MS combined with membrane-protected molecularly imprinted polymer micro-solid-phase extraction for synthetic cathinones monitoring in urine

Synthetic cathinones are a type of drug belonging to group of new psychoactive substances (NPSs). The illicit market for these substances is characterized by the continuous introduction to the market of new analogs to evade legislation and to avoid detection. New screening and confirmation assays are therefore needed, mainly in forensic/clinical samples. In the current development, a porous membrane-protected, micro-solid-phase extraction (μ-SPE) has been developed for the assessment of several cathinones in urine. The μ-SPE device consisted of a cone-shaped polypropylene (PP) porous membrane containing the adsorbent (molecularly imprinted polymers, MIPs, synthesized for the first time for this class of drugs). MIPs were prepared using ethylone and 3-methylmethcathinone (3-MMC) as templates, ethylene glycol dimethacrylate (EGDMA) as a functional monomer, divinylbenzene (DVB) as a cross-linker, and 2,2´-azobisisobutyronitrile (AIBN) as an initiator. The prepared ethylone-based MIP and 3-MMC-based MIP have been fully characterized and evaluated as new selective adsorbents for μ-SPE. Cathinones separation/determination was performed by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Optimum loading conditions (pH 5.0, loading for 4.0 minutes under orbital-horizontal shaking at 200 rpm) and elution conditions [2.0 mL of 75:20:5 heptane/2-propanol/ammonium hydroxide and ultrasounds assistance (37 kHz, 325 W) for 4.0 minutes] were found for ethylone-based MIP. Validation (intra-day and inter-day precision and analytical recovery) showed RSD values lower than 9 and 10% for intra-day and inter-day precision, and within the 88%-101% range for intra-day and inter-day analytical recovery.

In vitro human bioavailability of major, trace and ultra-trace elements in Chilean ‘natural’ wines from Itata Valley

In vitro human bioavailability of elements in ‘natural’ wines from Chile's Itata Valley has been assessed using an in vitro dialyzability approach.

Evaluation of Iodine Bioavailability in Seaweed Using in Vitro Methods

Due to the high levels of iodine present in seaweed, the ingestion of a large amount of this type of food can produce excessive intake of iodine. However, the food after ingestion undergoes different chemistry and physical processes that can modify the amount of iodine that reaches the systemic circulation (bioavailability). Studies on the bioavailability of iodine from food are scarce and indicate that the bioavailable amount is generally lower than ingested. Iodine in vitro bioavailability estimation from different commercialized seaweed has been studied using different in vitro approaches (solubility, dialyzability, and transport and uptake by intestinal cells). Results indicate that iodine is available after gastrointestinal digestion for absorption (bioaccessibility: 49-82%), kombu being the seaweed with the highest bioaccessibility. The incorporation of dialysis cell cultures to elucidate bioavailability modifies the estimation of the amount of iodine that may reach the systemic circulation (dialysis, 5-28%; cell culture, ≤3%). The paper discusses advantages and drawbacks of these methodologies for iodine bioavailability in seaweed.