Nanocompounds of iron and zinc: their potential in nutrition

Particulate iron oxide food colorants (E 172) during artificial digestion and their uptake and impact on intestinal cells

Iron oxide of various structures is frequently used as food colorant (E 172). The spectrum of colors ranges from yellow over orange, red, and brown to black, depending on the chemical structure of the material. E 172 is mostly sold as solid powder. Recent studies have demonstrated the presence of nanoscaled particles in E 172 samples, often to a very high extent. This makes it necessary to investigate the fate of these particles after oral uptake. In this study, 7 differently structured commercially available E 172 food colorants (2 x Yellow FeO(OH), 2 x Red Fe2O3, 1 x Orange Fe2O3 + FeO(OH) and 2 x Black Fe3O4) were investigated for particle dissolution, ion release, cellular uptake, crossing of the intestinal barrier and toxicological impact on intestinal cells. Dissolution was analyzed in water, cell culture medium and artificial digestion fluids. Small-angle X-ray scattering (SAXS) was employed for determination of the specific surface area of the colorants in the digestion fluids. Cellular uptake, transport and toxicological effects were studied using human differentiated Caco-2 cells as an in vitro model of the intestinal barrier. For all materials, a strong interaction with the intestinal cells was observed, albeit there was only a limited dissolution, and no toxic in vitro effects on human cells were recorded.

Advances in the Interaction between Food-Derived Nanoparticles and the Intestinal Barrier

The maintenance of the intestinal barrier is crucial for the overall balance of the gut and the organism. Dysfunction of the intestinal barrier is closely associated with intestinal diseases. In recent years, due to the increased presence of nanoparticles (NPs) in the human diet, there has been a growing concern regarding the safety and potential impact of these NPs on gastrointestinal health. The interactions between food-derived NPs and the intestinal barrier are numerous. This review provides an introduction to the structure and function of the intestinal barrier along with a comprehensive summary of the interactions between food NPs and the intestinal barrier. Additionally, we highlight the potential connection between the food NPs-induced dysfunction of the intestinal barrier and inflammatory bowel disease. Finally, we discuss the enhancement of food NPs on the repair of the intestinal barrier damage and the nutrients absorption. This review holds significant importance in furthering our understanding of the regulatory mechanisms of food-derived NPs on the intestinal barrier.

Effects of Iron Oxide Nanoparticle Supplementation on the Growth Performance, Serum Metabolites, Meat Quality, and Jejunal Basal Morphology in Broilers

The current research aimed to evaluate the supplemental effects of iron oxide nanoparticles (IONPs) on production performance, viscera development, blood metabolites, redox status, meat quality, and jejunal histology in broilers. A total of 300 day-old broilers were randomly divided into six groups with five replicates per group. Birds were fed on a corn soybean-based diet supplemented with 0, 20, 40, 60, or 80 mg/kg IONPs or 80 mg/kg of FeSO4 for 35 days. The feed conversion ratio (FCR) was improved in birds supplemented with 60 mg/kg IONPs. The pH24h was lower in birds supplemented with 40 mg/kg IONPs compared to that of the bulk group. Pectoral muscle fascicle diameter and fiber density were significantly increased in 20 mg/kg IONP-supplemented birds compared to those of the bulk group, respectively. The muscle fiber diameter was higher in 40 mg/kg IONP-supplemented birds compared with the bulk group. The jejunal villus height, crypt depth, and villus surface area were significantly increased with 60 mg/kg IONP supplementation, whereas villus width was decreased in birds supplemented with 40 mg/kg IONPs. The villus-height-to-crypt-depth ratio was lower in IONP-supplemented birds compared to the bulk group. IONP supplementation improved the FCR, jejunal, and pectoral muscle morphology without affecting the carcass characteristics and redox status of broilers.

Iron from nanostructured ferric phosphate: absorption and biodistribution in mice and bioavailability in iron deficient anemic women

Food fortification with iron nanoparticles (NPs) could help prevent iron deficiency anemia, but the absorption pathway and biodistribution of iron-NPs and their bioavailability in humans is unclear. Dietary non-heme iron is physiologically absorbed via the divalent metal transporter-1 (DMT1) pathway. Using radio- iron isotope labelling in mice with a partial knockdown of intestine-specific DMT1, we assessed oral absorption and tissue biodistribution of nanostructured ferric phosphate (FePO₄-NP; specific surface area [SSA] 98 m²g^-1) compared to to ferrous sulfate (FeSO₄), the reference compound. We show that absorption of iron from FePO₄-NP appears to be largely DMT1 dependent and that its biodistribution after absorption is similar to that from FeSO₄, without abnormal deposition of iron in the reticuloendothelial system. Furthermore, we demonstrate high bioavailability from iron NPs in iron deficient anemic women in a randomized, cross-over study using stable-isotope labelling: absorption and subsequent erythrocyte iron utilization from two ⁵⁷Fe-labeled FePO₄-NP with SSAs of 98 m²g⁻¹ and 188 m²g⁻¹ was 2.8-fold and 5.4-fold higher than from bulk FePO₄ with an SSA of 25 m²g⁻¹ (P < 0.001) when added to a rice and vegetable meal consumed by iron deficient anemic women. The FePO₄-NP 188 m²g^-1 achieved 72% relative bioavailability compared to FeSO₄. These data suggest FePO₄-NPs may be useful for nutritional applications.

The Role of Metal Oxide Nanoparticles, Escherichia coli, and Lactobacillus rhamnosus on Small Intestinal Enzyme Activity

Engineered nanomaterials (ENMs) have become common in the food industry, which motivates the need to evaluate ENM effects on human health. Gastrointestinal (GI) in vitro models (e.g. Caco-2, Caco-2/HT29-MTX) have been used in nanotoxicology research. However, the human gut environment is composed of both human cells and the gut microbiota. The goal of this study is to increase the complexity of the Caco-2/HT29-MTX in vitro model by co-culturing human cells with the Gram-positive, commensal Lactobacillus rhamnosus or the Gram-negative, opportunistic Escherichia coli; with the hypothesis that the presence of bacteria would ameliorate the effects of exposure to metal oxide nanoparticles (NPs) such as iron oxide (Fe2O3), silicone dioxide (SiO2), titanium dioxide (TiO2), or zinc oxide (ZnO). To understand this relationship, Caco-2/HT29-MTX cell barriers were acutely co-exposed (4 hours) to bacteria and/or NPs (pristine or in vitro digested). The activity of the brush border membrane (BBM) enzymes intestinal alkaline phosphatase (IAP), aminopeptidase-N (APN), sucrase isomaltase (SI) and the basolateral membrane enzyme (BLM) Na+/K+ ATPase were assessed. Findings show that (i) the human digestion process alters the physicochemical properties of NPs, (ii) large agglomerates of NPs remain entrapped on the apical side of the intestinal barrier, which (iii) affects the activity of BBM enzymes. Interestingly, some NPs effects were attenuated in the presence of either bacterial strains. Confocal microscopy detected bacteria-NPs interactions, which may impede the NP-intestinal cell contact. These results highlight the importance of improving in vitro models to closely mimic the complexities of the human body.

Adsorption of proteins on oral Zn2+ doped iron oxide nanoparticles in mouse stomach and in vitro: triggering nanoparticle aggregation

Oral route is one of the most important portals of nanoparticle entry to the body. However, in vivo protein corona formed in the gastrointestinal tract has not been studied owing to the difficulty for the recovery of nanoparticles from the in vivo environment. In this study, by using the magnetic property of iron oxide nanoparticles (Fe3O4 NPs) and Zn2+ doped iron oxide nanoparticles (Zn0.4Fe2.6O4 NPs), the nanoparticles were separated from the gastric fluid after oral administration in mice. The effects of Zn2+ doping and static magnetic field (SMF) treatment on the protein adsorption on the nanoparticles were investigated in vitro and in vivo. Zn2+ doping decreases the adsorption of pepsin on the nanoparticles in vitro and affects the composition of the protein corona in vivo and enhances protein adsorption-induced aggregation of the nanoparticles in vitro and in vivo. SMF treatment affects the composition of the protein corona of Fe3O4 NPs and Zn0.4Fe2.6O4 NPs, and enhances the aggregation of Fe3O4 NPs and Zn0.4Fe2.6O4 NPs in vivo. Furthermore, the results demonstrate that electrostatic attraction is the crucial force to drive adsorption of proteins on Fe3O4 NPs and Zn0.4Fe2.6O4 NPs and protein adsorption-induced change in the surface charge of nanoparticles plays an important role in the pH-dependent aggregation of the nanoparticles. In addition, the work provides the evidence that the protein adsorption-induced aggregation of Fe3O4 NPs and Zn0.4Fe2.6O4 NPs has no effect on their magnetic susceptibility. The results highlight that Zn0.4Fe2.6O4 NPs may be used as a potential oral magnetic resonance imaging contrast agent in diagnosis of gastrointestinal disease.

Potential of Nanonutraceuticals in Increasing Immunity

Nutraceuticals are defined as foods or their extracts that have a demonstrably positive effect on human health. According to the decision of the European Food Safety Authority, this positive effect, the so-called health claim, must be clearly demonstrated best by performed tests. Nutraceuticals include dietary supplements and functional foods. These special foods thus affect human health and can positively affect the immune system and strengthen it even in these turbulent times, when the human population is exposed to the COVID-19 pandemic. Many of these special foods are supplemented with nanoparticles of active substances or processed into nanoformulations. The benefits of nanoparticles in this case include enhanced bioavailability, controlled release, and increased stability. Lipid-based delivery systems and the encapsulation of nutraceuticals are mainly used for the enrichment of food products with these health-promoting compounds. This contribution summarizes the current state of the research and development of effective nanonutraceuticals influencing the body's immune responses, such as vitamins (C, D, E, B12, folic acid), minerals (Zn, Fe, Se), antioxidants (carotenoids, coenzyme Q10, polyphenols, curcumin), omega-3 fatty acids, and probiotics.

Renewable Polysaccharides Micro/Nanostructures for Food and Cosmetic Applications

The worldwide diffusion of nanotechnologies into products nowadays has completely revolutionized human life, providing novel comfort and benefits. Their inclusion in food and cosmetic has a heavy impact over the market, allowing the development of higher value products with enhanced properties. Natural origin polymers and in particular polysaccharides represent a versatile platform of materials for the development of micro/nanostructured additives for food and cosmetic products due to their chemical versatility, biocompatibility, and abundance. Here, we review the current applications of polysaccharides-based micro/nanostructures, taking into consideration the precursors' production, isolation, and extraction methods and highlighting the advantages, possible drawbacks, and market diffusion.

In Vitro Evaluation of Iron-Induced Salivary Lipid Oxidation Associated with Exposure to Iron Nanoparticles: Application Possibilities and Limitations for Food and Exposure Sciences

Zerovalent iron nanotechnologies are widely used for groundwater remediation and increasingly considered for advance oxidation treatment in drinking water applications. Iron nanoparticles have been detected in drinking water systems and considered for food fortification; therefore, the potential for human exposure through ingestion can be a concern. This study aimed to assess whether ingestion of iron nanoparticles from drinking water could be detected through flavor perception using In Vitro salivary lipid oxidation as an indicator for metallic flavor perception. Ten female subjects, aged 29–59 years, donated saliva samples for use in the In Vitro experiments. Test samples consisted of 1:1 mixture of saliva and bottled drinking water (control) and three treatment solutions, spiked with ferrous sulfate, stabilized zerovalent iron nanoparticles (nZVI), and an aggregated/microsized suspension of mixed zerovalent iron and microsized suspension of iron and iron oxide metal powder, (mZVI). Upon mixing, samples were subjected to 15 min incubation at 37 °C to resemble oral conditions. Salivary lipid oxidation (SLO) was measured in all samples as micromoles of thiobarbituric acid reactive substances (TBARS)/mg Fe. Exposure to iron in all three forms induced significant amount of SLO in all treatment samples as compared to the control (p < 0.0001). The mean SLO levels were the highest in the ferrous treatment, followed by nZVI and mZVI treatments; the differences in the mean SLO levels were significant (p < 0.05). The findings indicate that oral exposure to stabilized ZVI nanoparticles may induce sensory properties different from that of ferrous salt, likely predictive of diminished detection of metallic flavor by humans.

Nanofertilizer for Precision and Sustainable Agriculture: Current State and Future Perspectives

The increasing food demand as a result of the rising global population has prompted the large-scale use of fertilizers. As a result of resource constraints and low use efficiency of fertilizers, the cost to the farmer is increasing dramatically. Nanotechnology offers great potential to tailor fertilizer production with the desired chemical composition, improve the nutrient use efficiency that may reduce environmental impact, and boost the plant productivity. Furthermore, controlled release and targeted delivery of nanoscale active ingredients can realize the potential of sustainable and precision agriculture. A review of nanotechnology-based smart and precision agriculture is discussed in this paper. Scientific gaps to be overcome and fundamental questions to be answered for safe and effective development and deployment of nanotechnology are addressed.

Extrinsic iron from soil contributes to Hb regeneration of anaemic rats: implications for foods contaminated with soil iron

Contamination of foods with extrinsic (soil) Fe is common in developing countries. However, the bioavailability of this extrinsic Fe and the extent to which it contributes to Fe nutrition remains unknown. The present study compared the bioavailability of laboratory- and field-threshed teff (Eragrostisis tef (Zucc) Trotter) to evaluate the bioavailablity of extrinsic soil Fe that resulted from the traditional threshing of the staple grain. Using sequential extraction, Fe was fractionated and its solubility was evaluated. The contribution of the additional extrinsic (soil) Fe to the Hb regeneration of Fe-depleted rats was evaluated using a rat Hb depletion–repletion assay. Weanling male Wistar rats (n24) were fed Fe-deficient diet for 21 d, and were then repleted for 14 d with diets: either laboratory-threshed teff (35 mg Fe/kg;n 8), field-threshed teff (35 mg intrinsic Fe/kg+ 120 mg soil Fe/kg;n 8), or FeSO4(control;n8). Fe content of field-threshed teff (29·4 mg/100 g) was four times greater than that of the laboratory-threshed (6·7 mg/100 g) teff (P<0·05). Soil contamination significantly increased the exchangeable, acid-soluble and reducible fractions obtained after sequential extraction. The relative biological value of the field-threshed teff (88 %) was higher than that of the laboratory-threshed (68 %) teff (P<0·05). Soil Fe can contribute to Hb regeneration in Fe-deficient rats. Considering that contamination of foods with soil is common in Ethiopia and other developing countries, it needs to be accounted for in the design and implementation of fortification programmes to prevent excessive intakes. Human studies are needed to confirm the present findings.

Is nano safe in foods? Establishing the factors impacting the gastrointestinal fate and toxicity of organic and inorganic food-grade nanoparticles

Nanotechnology offers the food industry a number of new approaches for improving the quality, shelf life, safety, and healthiness of foods. Nevertheless, there is concern from consumers, regulatory agencies, and the food industry about potential adverse effects (toxicity) associated with the application of nanotechnology in foods. In particular, there is concern about the direct incorporation of engineered nanoparticles into foods, such as those used as delivery systems for colors, flavors, preservatives, nutrients, and nutraceuticals, or those used to modify the optical, rheological, or flow properties of foods or food packaging. This review article summarizes the application of both inorganic (silver, iron oxide, titanium dioxide, silicon dioxide, and zinc oxide) and organic (lipid, protein, and carbohydrate) nanoparticles in foods, highlights the most important nanoparticle characteristics that influence their behavior, discusses the importance of food matrix and gastrointestinal tract effects on nanoparticle properties, emphasizes potential toxicity mechanisms of different food-grade nanoparticles, and stresses important areas where research is still needed. The authors note that nanoparticles are already present in many natural and processed foods, and that new kinds of nanoparticles may be utilized as functional ingredients by the food industry in the future. Many of these nanoparticles are unlikely to have adverse affects on human health, but there is evidence that some of them could have harmful effects and that future studies are required.

Highly bioavailable nanocalcium from oyster shell for preventing osteoporosis in rats

Oyster shell is one of the foremost natural sources of calcium and is used as an alternative treatment for osteoporosis. In this study, we demonstrated that zinc-activated nanopowdered oyster shell (Zn-NPOS) effectively reduced bone loss compared with powdered oyster shell (POS) in an ovariectomized rat (OVX) model. As a result of nanosizing, the solubility and bioavailability of the oyster shell were greatly improved, and its effectiveness was further enhanced by zinc activation. Bone analysis indicated greater recovery from ovariectomy-induced bone loss following Zn-NPOS treatment. Moreover, Zn-NPOS treatment resulted in higher bone strength and superior trabecular architecture compared with NPOS and POS treatments. Furthermore, Zn-NPOS showed greater efficiency in increasing bone formation and reducing bone resorption markers. Therefore, nanosizing with zinc activation could be a viable strategy for improving the efficiency of oyster shells used for osteoporosis prevention.

The Role of the Food Matrix and Gastrointestinal Tract in the assessment of biological properties of ingested engineered nanomaterials (iENMs): State of the science and knowledge gaps

Many foods contain appreciable levels of engineered nanomaterials (ENMs) (diameter < 100 nm) that may be either intentionally or unintentionally added. These ENMs vary considerably in their compositions, dimensions, morphologies, physicochemical properties, and biological responses. From a toxicological point of view, it is often convenient to classify ingested ENMs (iENMs) as being either inorganic (such as TiO₂, SiO₂, Fe₂O₃, or Ag) or organic (such as lipid, protein, or carbohydrate), since the former tend to be indigestible and the latter are generally digestible. At present there is a relatively poor understanding of how different types of iENMs behave within the human gastrointestinal tract (GIT), and how the food matrix and biopolymers transform their physico-chemical properties and influence their gastrointestinal fate. This lack of knowledge confounds an understanding of their potential harmful effects on human health. The purpose of this article is to review our current understanding of the GIT fate of iENMs, and to highlight gaps where further research is urgently needed in assessing potential risks and toxicological implications of iENMs. In particular, a strong emphasis is given to the development of standardized screening methods that can be used to rapidly and accurately assess the toxicological properties of iENMs.

Evaluation of zinc-doped magnetite nanoparticle toxicity in the liver and kidney of mice after sub-chronic intragastric administration

Super-paramagnetic iron oxide nanoparticles (SPIONs) have been approved for clinical use due to their salient super-paramagnetic properties and low toxicity. Zn²⁺ doped SPIONs possess significantly higher magnetic susceptibility than that of conventional SPIONs. Here we evaluated the potential toxicity of Zn²⁺ doped Fe₃O₄ nanoparticles (Zn_0.4Fe_2.6O₄ NPs) in the liver and kidney of mice after repeated intragastric administration for 30 days. Zn_0.4Fe_2.6O₄ NPs did not cause significant changes in their body weights and the coefficients of the liver and kidney, but increased the levels of Fe and Zn in the two organs. Zn_0.4Fe_2.6O₄ NP induced slight oxidative stress in the liver and kidney, which could be successfully counteracted by their intrinsic antioxidant systems and had no observable hazardous effects on the histopathology, ultrastructure and functions of the two organs. These results demonstrated that high-performance magnetic Zn_0.4Fe_2.6O₄ NPs did not produce apparent toxicity in the liver and kidney of mice even after sub-chronic intragastric administration. In addition, Zn²⁺ doping not only markedly enhanced magnetic susceptibility of Zn_0.4Fe_2.6O₄ NPs but also significantly increased the stability of Zn_0.4Fe_2.6O₄ NPs in biological conditions, making them appropriate for use in magnetic resonance imaging and drug delivery by the oral route.

Safety assessment of chronic oral exposure to iron oxide nanoparticles

Iron oxide nanoparticles with engineered physical and biochemical properties are finding a rapidly increasing number of biomedical applications. However, a wide variety of safety concerns, especially those related to oral exposure, still need to be addressed for iron oxide nanoparticles in order to reach clinical practice. Here, we report on the effects of chronic oral exposure to low doses of γ-Fe2O3 nanoparticles in growing chickens. Animal observation, weight, and diet intake reveal no adverse signs, symptoms, or mortality. No nanoparticle accumulation was observed in liver, spleen, and duodenum, with feces as the main excretion route. Liver iron level and duodenal villi morphology reflect the bioavailability of the iron released from the partial transformation of γ-Fe2O3 nanoparticles in the acid gastric environment. Duodenal gene expression studies related to the absorption of iron from γ-Fe2O3 nanoparticles indicate the enhancement of a ferric over ferrous pathway supporting the role of mucins. Our findings reveal that oral administration of iron oxide nanoparticles is a safe route for drug delivery at low nanoparticle doses.

Multiscale Aspects of Modeling Gas-Phase Nanoparticle Synthesis

Aerosol reactors are utilized to manufacture nanoparticles in industrially relevant quantities. The development, understanding and scale-up of aerosol reactors can be facilitated with models and computer simulations. This review aims to provide an overview of recent developments of models and simulations and discuss their interconnection in a multiscale approach. A short introduction of the various aerosol reactor types and gas-phase particle dynamics is presented as a background for the later discussion of the models and simulations. Models are presented with decreasing time and length scales in sections on continuum, mesoscale, molecular dynamics and quantum mechanics models.

Dual enzyme-like activities of iron oxide nanoparticles and their implication for diminishing cytotoxicity

Iron oxide nanoparticles (IONPs) are frequently used in biomedical applications, yet their toxic potential is still a major concern. While most studies of biosafety focus on cellular responses after exposure to nanomaterials, little is reported to analyze reactions on the surface of nanoparticles as a source of cytotoxicity. Here we report that different intracellular microenvironment in which IONPs are located leads to contradictive outcomes in their abilities to produce free radicals. We first verified pH-dependent peroxidase-like and catalase-like activities of IONPs and investigated how they interact with hydrogen peroxide (H(2)O(2)) within cells. Results showed that IONPs had a concentration-dependent cytotoxicity on human glioma U251 cells, and they could enhance H(2)O(2)-induced cell damage dramatically. By conducting electron spin resonance spectroscopy experiments, we showed that both Fe(3)O(4) and γ-Fe(2)O(3) nanoparticles could catalyze H(2)O(2) to produce hydroxyl radicals in acidic lysosome mimic conditions, with relative potency Fe(3)O(4) > γ-Fe(2)O(3), which was consistent with their peroxidase-like activities. However, no hydroxyl radicals were observed in neutral cytosol mimic conditions with both nanoparticles. Instead, they decomposed H(2)O(2) into H(2)O and O(2) directly in this condition through catalase-like activities. Transmission electron micrographs revealed that IONPs located in lysosomes in cells, the acidic environment of which may contribute to hydroxyl radical production. This is the first study regarding cytotoxicity based on their enzyme-like activities. Since H(2)O(2) is continuously produced in cells, our data indicate that lysosome-escaped strategy for IONP delivery would be an efficient way to diminish long-term toxic potential.

Design of nanomaterial synthesis by aerosol processes

Aerosol synthesis of materials is a vibrant field of particle technology and chemical reaction engineering. Examples include the manufacture of carbon blacks, fumed SiO(2), pigmentary TiO(2), ZnO vulcanizing catalysts, filamentary Ni, and optical fibers, materials that impact transportation, construction, pharmaceuticals, energy, and communications. Parallel to this, development of novel, scalable aerosol processes has enabled synthesis of new functional nanomaterials (e.g., catalysts, biomaterials, electroceramics) and devices (e.g., gas sensors). This review provides an access point for engineers to the multiscale design of aerosol reactors for the synthesis of nanomaterials using continuum, mesoscale, molecular dynamics, and quantum mechanics models spanning 10 and 15 orders of magnitude in length and time, respectively. Key design features are the rapid chemistry; the high particle concentrations but low volume fractions; the attainment of a self-preserving particle size distribution by coagulation; the ratio of the characteristic times of coagulation and sintering, which controls the extent of particle aggregation; and the narrowing of the aggregate primary particle size distribution by sintering.