Synthesis, characterization, and bioavailability in rats of ferric phosphate nanoparticles

Ferrous Pyrophosphate and Mixed Divalent Pyrophosphates as Delivery Systems for Essential Minerals

Poorly water-soluble iron-containing compounds are promising iron fortificants. However, ensuring high bioaccessibility and low reactivity of iron is challenging. We present the potential application of ferrous pyrophosphate (Fe(II)PP) and Fe(II)-containing M2(1-x)Fe2x P2O7 salts (0 < x < 1, M = Ca, Zn, or Mn) for delivery of iron and a second essential mineral (M). After preparation by a facile and environment-friendly coprecipitation method, the salts were investigated for their composition, pH-dependent dissolution, iron-mediated discoloration of a black tea solution, and oxidation of vitamin C. Our results suggest that these salts are possible dual-fortificants with tunable composition that compared to Fe(II)PP (i) show lower (<0.5 mM) and enhanced (to 5 mM) iron dissolution in moderate and gastric pH, respectively, (ii) exhibit less discoloration and dissolved iron in tea when x = 0.470 for M = Ca or Zn and x = 0.086 for M = Mn, and (iii) do not increase the oxidation extent of vitamin C over 48 h when x = 0.06, 0.086, or 0.053 for M = Ca, Zn, or Mn, respectively.

Nanoscale coordination polymer Fe-DMY downregulating Poldip2-Nox4-H2O2 pathway and alleviating diabetic retinopathy

Diabetic retinopathy (DR) is a prevalent microvascular complication of diabetes and the leading cause of blindness and severe visual impairment in adults. The high levels of glucose trigger multiple intracellular oxidative stress pathways, such as POLDIP2, resulting in excessive reactive oxygen species (ROS) production and increased expression of vascular cell adhesion molecule-1 (VCAM-1), hypoxia-inducible factor 1α (HIF-1α), and vascular endothelial growth factor (VEGF), causing microvascular dysfunction. Dihydromyricetin (DMY) is a natural flavonoid small molecule antioxidant. However, it exhibits poor solubility in physiological environments, has a short half-life in vivo, and has low oral bioavailability. In this study, we present, for the first time, the synthesis of ultra-small Fe-DMY nano-coordinated polymer particles (Fe-DMY NCPs), formed by combining DMY with low-toxicity iron ions. In vitro and in vivo experiments confirm that Fe-DMY NCPs alleviate oxidative stress-induced damage to vascular endothelial cells by high glucose, scavenge excess ROS, and improve pathological features of DR, such as retinal vascular leakage and neovascularization. Mechanistic validation indicates that Fe-DMY NCPs can inhibit the activation of the Poldip2-Nox4-H2O2 signaling pathway and downregulate vital vascular function indicators such as VCAM-1, HIF-1α, and VEGF. These findings suggest that Fe-DMY NCPs could serve as a safe and effective antioxidant and microangio-protective agent, with the potential as a novel multimeric drug for DR therapy.

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.

Biocompatible FePO4 Nanoparticles: Drug Delivery, RNA Stabilization, and Functional Activity

FePO4 NPs are of special interest in food fortification and biomedical imaging because of their biocompatibility, high bioavailability, magnetic property, and superior sensory performance that do not cause adverse organoleptic effects. These characteristics are desirable in drug delivery as well. Here, we explored the FePO4 nanoparticles as a delivery vehicle for the anticancer drug, doxorubicin, with an optimum drug loading of 26.81% ± 1.0%. This loading further enforces the formation of Fe3+ doxorubicin complex resulting in the formation of FePO4-DOX nanoparticles. FePO4-DOX nanoparticles showed a good size homogeneity and concentration-dependent biocompatibility, with over 70% biocompatibility up to 80 µg/mL concentration. Importantly, cytotoxicity analysis showed that Fe3+ complexation with DOX in FePO4-DOX NPs enhanced the cytotoxicity by around 10 times than free DOX and improved the selectivity toward cancer cells. Furthermore, FePO4 NPs temperature-stabilize RNA and support mRNA translation activity showing promises for RNA stabilizing agents. The results show the biocompatibility of iron-based inorganic nanoparticles, their drug and RNA loading, stabilization, and delivery activity with potential ramifications for food fortification and drug/RNA delivery.

Biodegradable Zinc Oxide Nanoparticles Doped with Iron as Carriers of Exogenous Iron in the Living Organism

Iron plays an important role in various crucial processes in the body and its deficiency is considered currently as a serious health problem. Thus, iron supplementation strategies for both humans and animals need to be effective and safe. According to our previous studies, zinc-based nanoparticles provide safe, biodegradable, fast and efficient transport system of orally given substances to the tissues. In the current manuscript we present results of a study aimed at investigation of the ZnO nanoparticle-based Fe supplementation system (average size 100 × 250 nm). Nanostructures were orally (gavage) administered to adult mice. Animals were sacrificed at different time points with collection of blood and internal organs for analyses (tissue iron concentration, hepatic level of hepcidin, blood parameters, liver and spleen levels of ferritin, histopathology). Initial experiment was performed to compare the biological effect of doping type (Fe³⁺ doping vs. a mixture of Fe³⁺ and Fe²⁺). Then, the effect of acute/chronic exposure models was determined. The increase in ferritin, along with improved, crucial hematological parameters and lack of the influence on hepcidin expression indicated the chronic application of Fe^3+,2+ doped ZnO nanostructures to be the most effective among tested.

Iron nanoparticles as a promising compound for food fortification in iron deficiency anemia: a review

Abstract

Iron deficiency anemia (IDA) is a global health concern that is affecting all age groups significantly. Among many of the existing methods, the fortification of foods with iron salts is the best and most cost-effective strategy for targeting large-scale populations to provide nutritional security. The fortification of foods with iron salts is a challenging task because most iron complexes (ferrous sulfate, ferrous chloride) used in fortification are highly water-soluble, which impart unacceptable organoleptic changes in food vehicles and also causes gastrointestinal problems. However, insoluble iron salts (ferric pyrophosphate) do not cause unacceptable taste or color in food vehicles but low bioavailable. Nanosized iron salts can overcome these concerns. The particle size of iron salts has been reported to play an important role in the absorption of iron. Reduction in the particle size of iron compounds increases its surface area, which in turn improves its solubility in the gastric juice leading to higher absorption. Nanosized iron compound produces minimal organoleptic changes in food vehicles compared to water-soluble iron complexes. Thus nanosized iron salts find potential applications in food fortification to reduce IDA. This paper focuses on providing a complete review of the various iron salts used in IDA, including their bioavailability, the challenges to food fortification, the effects of nanosized iron salts on IDA, and their applications in food fortification.

Graphic abstract

Fortification of foods with water-soluble Fe salts imparts unacceptable organoleptic changes in food vehicle and adverse impact on health. However, insoluble iron salts do not cause unacceptable taste or color in food vehicles but low bioavailable. Using Nano-sized iron compound produces minimal organoleptic changes in food vehicles compared to changes produced by water-soluble iron complexes, improves Fe absorption in the gastrointestinal tract and does not cause any health issues.

Elucidating the effect of specific surface area on the gastrointestinal absorption of nanostructured calcium through Calcium-45 in vivo radiotracing

Low dietary calcium intake and absorption may increase the risk of hypocalcaemia disease states. Reducing the particle size of calcium-containing powders and increasing the specific surface area (SSA), may have high oral calcium bioavailability. The absorption of a single dose of different sized calcium carbonate nanoparticles was traced in Sprague-Dawley rats with radioactive calcium-45 (half-life = 162.6 days, β^- endpoint = 258 keV; 100%). Four calcium carbonate formulations (calcium-45) were administered to Sprague-Dawley rodents (6 per treatment; n = 24). The groups were [⁴⁵Ca]CaCO₃ SSA 3 m²/g, [⁴⁵Ca]CaCO₃ 36 m²/g, [⁴⁵Ca]CaCO₃ 64 m²/g and a separate [⁴⁵Ca]CaCO₃ 36 m²/g formulation produced by flame assisted pyrolysis. Blood and urine were sampled periodically, and organs collected and analysed after euthanasia. No changes in SSA or crystallinity were observed when powders before or after irradiation were compared. The [⁴⁵Ca]CaCO₃ 64 m²/g formulation presented with higher levels in blood 2 h after administration and a higher liver and femur concentration. These findings suggest [⁴⁵Ca]CaCO₃ 64 m²/g could lead to increased oral bioavailability.

Development of a novel polysaccharide-based iron oxide nanoparticle to prevent iron accumulation-related osteoporosis by scavenging reactive oxygen species

In this work, the biological polysaccharide-based antioxidant polyglucose-sorbitol-carboxymethyl ether (PSC) was used as the precursor to synthesize Fe₂O₃@PSC nanoparticles, which are expected to scavenge excess reactive oxygen species (ROS) to inhibit osteogenesis and promote osteoclast differentiation in iron accumulation (IA)-related osteoporosis. The Fe₂O₃@PSC nanoparticles obtained were of a uniform particle size of 7.3 nm with elemental O/Fe/Cl/C at a ratio of 190:7:2:88. In addition, the Fe₂O₃@PSC nanoparticles showed the ability to supply equivalent amounts of iron as the typical iron agent ferric ammonium citrate (FAC) in vitro and in vivo. Importantly, the Fe₂O₃@PSC nanoparticles not only induced antioxidative MC3T3-E1 and Raw 264.7 cells to scavenge ROS but also promoted osteogenic differentiation by activating Akt-GSK-3β-β-catenin and inhibiting osteoclast differentiation by inhibiting the MAPK and NF-κB pathways in vitro. In vivo, no IA-related osteoporosis was induced in a mouse model when enough iron was supplied by the Fe₂O₃@PSC nanoparticles. Overall, the biological polysaccharide-based antioxidant PSC can supply iron and prevent IA-related osteoporosis, indicating that it is a promising novel iron agent for applications to treat iron deficiency diseases.

The effects of titanium nanoparticles on enzymatic and non-enzymatic biomarkers in female Wistar rats

Titanium dioxide (TiO₂) nanoparticles (NPs) are widely used in industry, pharmacy, medicine, and food sectors. Therefore, this study deals with the effects of TiO₂ NPs in female rats following oral administration in differing doses for 14 days (0, 0.5, 5, and 50 mg/kg b.w./d). The response of enzymatic biomarkers (Na,K-ATPase, Mg-ATPase, and AChE) was measured in the brain, kidney, and small intestine, while non-enzymatic biomarker levels, such as different forms of glutathione (GSH) and thiobarbituric acid reactive substances (TBARSs) were measured in the liver. The images of the tissues were obtained using a transmission electron microscope (TEM) to demonstrate TiO₂ NP accumulation. Data showed that brain AChE activity decreased at all TiO₂ NP doses, though brain ATPase activities increased. However, ATPase activities in the intestine and kidney did not change significantly. Levels of GSH forms did not change significantly, though there was a significant decrease in TBARS level at the highest NP dose. TEM images demonstrated that TiO₂ NPs accumulated in a dose-dependent manner in the tissues. Data emphasized that the brain was the most sensitive organ against the effects of TiO₂ NPs. This study suggests the need for further studies to evaluate better the toxic effects of TiO₂ NPs.

Bacteria-assisted biogreen synthesis of radical scavenging exopolysaccharide-iron complexes: an oral nano-sized nutritional supplement with high in vivo compatibility

Microbial exopolysaccharides (EPSs) have recently served as an efficient substrate for the production of biocompatible metal nanoparticles (NPs) given their favorable stabilizing and reducing properties due to the presence of polyanionic functional groups in their structure. In the present work, Pantoea sp. BCCS 001 GH was used to produce EPS-stabilized biogenic Fe NPs as a complex through a novel biosynthesis reaction. Physicochemical characterization of the EPS-Fe complex was performed, indicating high thermal stability, desirable magnetic properties due to the uniform distribution of the Fe NPs with the average size of ∼10 nm and spherical shape within the EPS matrix. In addition, the in vivo toxicity of the EPS-stabilized Fe NPs was evaluated to investigate their potential for the treatment of iron deficiency anemia. Biological blood parameters and organ histology studies confirmed very high safety of the biosynthesized composite, making EPS-Fe a suitable candidate with an economical and environment friendly synthesis method for a wide spectrum of potential fields in medicine.

Responses of biomarkers belonging to different metabolic systems of rats following oral administration of aluminium nanoparticle

Nanoparticle (NP) forms of aluminium oxide (Al₂O₃) are used in various fields such as engineering, pharmacy, medicine etc. Compounds containing aluminium oxide NPs may present toxic effects after certain thresholds. Thus, the present study was carried out to determine the effects of Al₂O₃ nanoparticles (Al-NPs) in rats. For this aim, different doses (0, 0.5, 5, 50 mg/kg b.w./day) of Al NP (˜40 nm) were orally administered to female rats (Rattus norvegicus var. albinus) for 14 days and the response of several biomarkers such as activities of ATPases (total ATPase, Na,K-ATPase, Mg-ATPase) and acetylcholinesterase (AChE), levels of different glutathione forms and thiobarbituric acid reactive substances (TBARS) were measured in different tissues. Additionally, tissue accumulation of Al-NPs was demonstrated by a transmission electron microscope (TEM). The images showed the presence of Al-NP aggregates in all the tissues at all doses. The sizes of NP aggregates were dependent on NP doses and it was a bit more loose in the brain than in the liver and kidney. AChE activity in the brain decreased significantly at all NP doses, whereas TBARS levels in the liver did not alter significantly at any NP dose. Although there was no significant change in ATPase activities in the intestine at any NP dose, there were significant decreases in the kidney and brain. There were some variations in the levels of total glutathione (tGSH), oxidized glutathione (GSSG) and reduced glutathione (rGSH), though these variations were not significant (P > 0.05). Likewise, the ratio of rGSH/GSSG also did not differ significantly among NP doses and control. The brain seems most affected organ following Al-NP administration. This study demonstrated that most biomarkers in the tissues of rats were affected by Al-NP, showing the signal of toxic effects and suggests further studies to understand better the effects of Al NPs, especially in their use for pharmacology.

Nano-delivery of trace minerals for marine fish larvae: influence on skeletal ossification, and the expression of genes involved in intestinal transport of minerals, osteoblast differentiation, and oxidative stress response

Currently, the larviculture of many marine fish species with small-sized larvae depends for a short time after hatching, on the supply of high-quality live zooplankton to ensure high survival and growth rates. During the last few decades, the research community has made great efforts to develop artificial diets, which can completely substitute live prey. However, studies aimed at determining optimal levels of minerals in marine larvae compound feeds and the potential of novel delivery vectors for mineral acquisition has only very recently begun. Recently, the agro-food industry has developed several nano-delivery systems, which could be used for animal feed, too. Delivery through nano-encapsulation of minerals and feed additives would protect the bioactive molecules during feed manufacturing and fish feeding and allow an efficient acquisition of active substances into biological system. The idea is that dietary minerals in the form of nanoparticles may enter cells more easily than their larger counterparts enter and thus speed up their assimilation in fish. Accordingly, we evaluated the efficacy of early weaning diets fortified with organic, inorganic, or nanoparticle forms of trace minerals (Se, Zn, and Mn) in gilthead seabream (Sparus aurata) larvae. We tested four experimental diets: a trace mineral-deficient control diet, and three diets supplemented with different forms of trace minerals. At the end of the feeding trial, larvae growth performance and ossification, and the level of expression of six target genes (SLC11A2β, dmt1, BMP2, OC, SOD, GPX), were evaluated. Our data demonstrated that weaning diets supplemented with Mn, Se, and Zn in amino acid-chelated (organic) or nanoparticle form were more effective than diets supplemented with inorganic form of minerals to promote bone mineralization, and prevent skeletal anomalies in seabream larvae. Furthermore, nanometals markedly improved larval stress resistance in comparison to inorganic minerals and upregulated mRNA copy number of OC gene. The expression of this gene was strongly correlated with mineralization degree, thus confirming its potency as a good marker of bone mineralization in gilthead seabream larvae.

One-Pot Facile Fabrication of Bioavailable Iron Nanoparticles with Good Biocompatibility for Anemia Therapy

Background

Iron deficiency anemia (IDA) has been a major public health problem all over the world. Developing new iron (Fe) fortificants with both high bioavailability and negligible food sensory changes for IDA is in urgent demand.

Material/Methods

The Fe nanoparticles were fabricated through a one-pot reduction process under the protection of bovine serum albumin (BSA). The BSA-Fe nanoparticles were characterized systematically. The comparisons between BSA-Fe nanoparticles and FeSO₄ in bioavailability were carried out through hemoglobin (Hb) repletion method. The biocompatibility of BSA-Fe nanoparticles was also investigated through in vitro and in vivo assays.

Results

BSA-Fe nanoparticles have super-small size and good water solubility as well as water stability. The Hb repletion assay demonstrated that BSA-Fe nanoparticles have comparative bioavailability with FeSO₄. The in vitro cell viability assay, in vivo histological analysis, and biochemical measurements proved the remarkable biocompatibility of BSA-Fe nanoparticles.

Conclusions

The BSA-Fe nanoparticles fabricated through a one-pot facile method have good water solubility, comparative bioavailability with FeSO₄, and acceptable biocompatibility, exhibiting good potential for further clinical translations.

Assessment of biotoxicity of Cu nanoparticles with respect to probiotic strains of microorganisms and representatives of the normal flora of the intestine of broiler chickens

Copper nanoparticle Cu (d = 55 ± 15 nm) and CuO nanoparticles (d = 90 ± 10 nm) were used in the studies (OOO Platina, Russia). Using the method of pure cultures, we extracted Lactobacillus, Enterococcus, and Enterobacterium from the intestines of broilers. Additionally, strains of Bacillus subtilis 10641 and Bifidobacterium were involved in probiotic strains. The data obtained in the course of the study testify to the insignificant biotoxicity of copper nanoparticles with respect to representatives of the genera Lactobacillus (30 to 15 μg/ml) and Bifidobacterium (30 μg/ml), with the most sensitive bacteria being the genus Lactobacillus, for which a concentration of 7.5 μg/ml was subinhibitory. The second stage was the study using method of agar wells. In the course of the experiment, we obtained results confirming the data of the research by the serial dilution method. In this case, as in the first case, the data indicate the insignificant biotoxicity of copper nanoparticles in relation to representatives of the genera Lactobacillus and Bifidobacterium. We have studied the bioaccumulating ability of microorganisms of the studied metals. In all the studies carried out, as in the first series of experiments, representatives of the genera Lactobacillus and Bifidobacterium with the lowest bioaccumulative ability were the most sensitive to copper nanoparticles and were 3.1 and 8.2%, respectively. The use of nanoparticles as a component of the fodder additive in small concentrations does not adversely affect not only the probiotic strains, but also the main representatives of the normoflora (Lactobacillus, Enterococcus, and Enterobacterium) of the poultry, the positive effect of the copper nanoparticles being directly related to low level of dissociation of nanoparticles, since biologically active ions will be released much more slowly, thereby creating a prolonged effect of exposure.

Iron Absorption from Iron-Enriched Aspergillus oryzae Is Similar to Ferrous Sulfate in Healthy Female Subjects

BACKGROUND

Iron deficiency anemia (IDA) remains a global health issue, affecting mainly children and adolescent and pregnant women. Because of problems associated with current iron compounds used in both supplementation and fortification areas, there is an emerging interest in new natural iron sources to combat IDA.

OBJECTIVE

The objective of this study was to compare the iron absorption of iron-enriched Aspergillus oryzae [Aspiron (ASP)] with FeSO4 in humans.

METHODS

Iron absorption was assessed using stable isotope and serum iron response methods after oral intake of iron by healthy women in 2 separate studies. In the first study, ASP was intrinsically labelled with 58Fe into a dry form containing 8% iron. Subjects (n = 16, 18-35 y) were randomly assigned to consume liquid semipurified meals labelled with 2 stable iron isotopes, 57FeSO4 (10 mg) and ASP containing 2 mg 58Fe and 8 mg natural abundance iron, in 2 visits. Isotope enrichment was measured 2 wk after the last meal was eaten. In the second study, 17 subjects were randomly assigned to consume a test meal with 3 iron supplements during 3 separate visits: FeSO4, 10 mg Fe, and ASP in 2 iron doses, 10 mg and 20 mg. Changes in serum iron were measured at regular intervals for 4 h after supplementation.

RESULTS

The first study showed that the difference in iron absorption from FeSO4 and ASP was not significant (17.18% ± 14.2% compared to 15.14% ± 12.3%; P = 0.07). The results of the second study suggested that the iron from ASP was released slowly compared to FeSO4 and the area under the curve did not reflect the absorption of ASP iron, but rather the rate of iron release.

CONCLUSIONS

Iron-enriched A. oryzae has high relative bioavailability and may cause lower iron surges into the blood compared to FeSO4.

Iron oxide nanoparticles can cross plasma membranes

Iron deficiency is a major global public health problem despite decades of efforts with iron supplementation and fortification. The issue lies on the poor tolerability of the standard of care soluble iron salts, leading to non-compliance and ineffective correction of iron-deficiency anaemia. Iron nanoformulations have been proposed to fortify food and feed to address these issues. Since it was just postulated that some nanoparticles (NPs) might cross the plasma membrane also by a non-endocytotic pathway gaining direct access to the cytoplasm, we have studied iron NP uptake under this perspective. To this aim, we have used a recently tested protocol that has proven to be capable of following the cytoplasmic changes of iron concentration dynamics and we have demonstrated that iron oxide NPs, but not zerovalent iron NPs nor iron oxide NPs that were surrounded by a protein corona, can cross plasma membranes. By electrophysiology, we have also shown that a small and transient increase of membrane conductance parallels NP crossing of plasma membrane.

Amyloid fibril systems reduce, stabilize and deliver bioavailable nanosized iron

Iron-deficiency anaemia (IDA) is a major global public health problem. A sustainable and cost-effective strategy to reduce IDA is iron fortification of foods, but the most bioavailable fortificants cause adverse organoleptic changes in foods. Iron nanoparticles are a promising solution in food matrices, although their tendency to oxidize and rapidly aggregate in solution severely limits their use in fortification. Amyloid fibrils are protein aggregates initially known for their association with neurodegenerative disorders, but recently described in the context of biological functions in living organisms and emerging as unique biomaterial building blocks. Here, we show an original application for these protein fibrils as efficient carriers for iron fortification. We use biodegradable amyloid fibrils from β-lactoglobulin, an inexpensive milk protein with natural reducing effects, as anti-oxidizing nanocarriers and colloidal stabilizers for iron nanoparticles. The resulting hybrid material forms a stable protein-iron colloidal dispersion that undergoes rapid dissolution and releases iron ions during acidic and enzymatic in vitro digestion. Importantly, this hybrid shows high in vivo iron bioavailability, equivalent to ferrous sulfate in haemoglobin-repletion and stable-isotope studies in rats, but with reduced organoleptic changes in foods. Feeding the rats with these hybrid materials did not result in abnormal iron accumulation in any organs, or changes in whole blood glutathione concentrations, inferring their primary safety. Therefore, these iron-amyloid fibril hybrids emerge as novel, highly effective delivery systems for iron in both solid and liquid matrices.

MyD88-dependent pro-interleukin-1β induction in dendritic cells exposed to food-grade synthetic amorphous silica

BACKGROUND

Dendritic cells (DCs) are specialized first-line sensors of foreign materials invading the organism. These sentinel cells rely on pattern recognition receptors such as Nod-like or Toll-like receptors (TLRs) to launch immune reactions against pathogens, but also to mediate tolerance to self-antigens and, in the intestinal milieu, to nutrients and commensals. Since inappropriate DC activation contributes to inflammatory diseases and immunopathologies, a key question in the evaluation of orally ingested nanomaterials is whether their contact with DCs in the intestinal mucosa disrupts this delicate homeostatic balance between pathogen defense and tolerance. Here, we generated steady-state DCs by incubating hematopoietic progenitors with feline McDonough sarcoma-like tyrosine kinase 3 ligand (Flt3L) and used the resulting immature DCs to test potential biological responses against food-grade synthetic amorphous silica (SAS) representing a common nanomaterial generally thought to be safe.

RESULTS

Interaction of immature and unprimed DCs with food-grade SAS particles and their internalization by endocytic uptake fails to elicit cytotoxicity and the release of interleukin (IL)-1α or tumor necrosis factor-α, which were identified as master regulators of acute inflammation in lung-related studies. However, the display of maturation markers on the cell surface shows that SAS particles activate completely immature DCs. Also, the endocytic uptake of SAS particles into these steady-state DCs leads to induction of the pro-IL-1β precursor, subsequently cleaved by the inflammasome to secrete mature IL-1β. In contrast, neither pro-IL-1β induction nor mature IL-1β secretion occurs upon internalization of TiO2 or FePO4 nanoparticles. The pro-IL-1β induction is suppressed by pharmacologic inhibitors of endosomal TLR activation or by genetic ablation of MyD88, a downstream adapter of TLR pathways, indicating that endosomal pattern recognition is responsible for the observed cytokine response to food-grade SAS particles.

CONCLUSIONS

Our results unexpectedly show that food-grade SAS particles are able to directly initiate the endosomal MyD88-dependent pathogen pattern recognition and signaling pathway in steady-state DCs. The ensuing activation of immature DCs with de novo induction of pro-IL-1β implies that the currently massive use of SAS particles as food additive should be reconsidered.

Iron phosphate nanoparticles for food fortification: Biological effects in rats and human cell lines

Nanotechnology offers new opportunities for providing health benefits in foods. Food fortification with iron phosphate nanoparticles (FePO₄ NPs) is a promising new approach to reducing iron deficiency because FePO₄ NPs combine high bioavailability with superior sensory performance in difficult to fortify foods. However, their safety remains largely untested. We fed rats for 90 days diets containing FePO₄ NPs at doses at which iron sulfate (FeSO₄), a commonly used food fortificant, has been shown to induce adverse effects. Feeding did not result in signs of toxicity, including oxidative stress, organ damage, excess iron accumulation in organs or histological changes. These safety data were corroborated by evidence that NPs were taken up by human gastrointestinal cell lines without reducing cell viability or inducing oxidative stress. Our findings suggest FePO₄ NPs appear to be as safe for ingestion as FeSO₄.

Mechanisms of Iron Uptake from Ferric Phosphate Nanoparticles in Human Intestinal Caco-2 Cells

Food fortification programs to reduce iron deficiency anemia require bioavailable forms of iron that do not cause adverse organoleptic effects. Rodent studies show that nano-sized ferric phosphate (NP-FePO₄) is as bioavailable as ferrous sulfate, but there is controversy over the mechanism of absorption. We undertook in vitro studies to examine this using a Caco-2 cell model and simulated gastrointestinal (GI) digestion. Supernatant iron concentrations increased inversely with pH, and iron uptake into Caco-2 cells was 2–3 fold higher when NP-FePO₄ was digested at pH 1 compared to pH 2. The size and distribution of NP-FePO₄ particles during GI digestion was examined using transmission electron microscopy. The d50 of the particle distribution was 413 nm. Using disc centrifugal sedimentation, a high degree of agglomeration in NP-FePO₄ following simulated GI digestion was observed, with only 20% of the particles ≤1000 nm. In Caco-2 cells, divalent metal transporter-1 (DMT1) and endocytosis inhibitors demonstrated that NP-FePO₄ was mainly absorbed via DMT1. Small particles may be absorbed by clathrin-mediated endocytosis and micropinocytosis. These findings should be considered when assessing the potential of iron nanoparticles for food fortification.

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.

Potential of Alginate Encapsulated Ferric Saccharate Microemulsions to Ameliorate Iron Deficiency in Mice

Iron deficiency is one of the most prominent mineral deficiencies around the world, which especially affects large population of women and children. Development of new technologies to combat iron deficiency is on high demand. Therefore, we developed alginate microcapsule with encapsulated iron that had better oral iron bioavailability. Microcapsules containing iron with varying ratios of sodium alginate ferric(III)-saccharide were prepared using emulsification method. In vitro studies with Caco-2 cells suggested that newly synthesized microemulsions had better iron bioavailability as compared to commercially available iron dextran formulations. Ferrozine in vitro assay showed that alginate-encapsulated ferric galactose microemulsion (AFGM) had highest iron bioavailability in comparison to other four ferric saccharate microemulsions, namely AFGlM, AFMM, AFSM, and AFFM synthesized in our laboratory. Mice studies also suggested that AFGM showed higher iron absorption as indicated by increased serum iron, hemoglobin, and other hematopoietic measures with almost no toxicity at tested doses. Development of iron-loaded microemulsions leads to higher bioavailability of iron and can provide alternative strategies to treat iron deficiency.

Particle Size, Surface Area, and Amorphous Content as Predictors of Solubility and Bioavailability for Five Commercial Sources of Ferric Orthophosphate in Ready-To-Eat Cereal

Ferric orthophosphate (FePO₄) has had limited use as an iron fortificant in ready-to-eat (RTE) cereal because of its variable bioavailability, the mechanism of which is poorly understood. Even though FePO₄ has desirable sensory properties as compared to other affordable iron fortificants, few published studies have well-characterized its physicochemical properties. Semi-crystalline materials such as FePO₄ have varying degrees of molecular disorder, referred to as amorphous content, which is hypothesized to be an important factor in bioavailability. The objective of this study was to systematically measure the physicochemical factors of particle size, surface area, amorphous content, and solubility underlying the variation in FePO₄ bioavailability. Five commercial FePO₄ sources and ferrous sulfate were added to individual batches of RTE cereal. The relative bioavailability value (RBV) of each iron source, determined using the AOAC Rat Hemoglobin Repletion Bioassay, ranged from 51% to 99% (p < 0.05), which is higher than typically reported. Solubility in dilute HCl accurately predicted RBV (R² = 0.93, p = 0.008). Amorphous content measured by Dynamic Vapor Sorption ranged from 1.7% to 23.8% and was a better determinant of solubility (R² = 0.91; p = 0.0002) than surface area (R² = 0.83; p = 0.002) and median particle size (R² = 0.59; p = 0.12). The results indicate that while solubility of FePO₄ is highly predictive of RBV, solubility, in turn, is strongly linked to amorphous content and surface area. This information may prove useful for the production of FePO₄ with the desired RBV.

Assessment of morphological and functional changes in organs of rats after intramuscular introduction of iron nanoparticles and their agglomerates

The research was performed on male Wistar rats based on assumptions that new microelement preparations containing metal nanoparticles and their agglomerates had potential. Morphological and functional changes in tissues in the injection site and dynamics of chemical element metabolism (25 indicators) in body were assessed after repeated intramuscular injections (total, 7) with preparation containing agglomerate of iron nanoparticles. As a result, iron depot was formed in myosymplasts of injection sites. The quantity of muscle fibers having positive Perls' stain increased with increasing number of injections. However, the concentration of the most chemical elements and iron significantly decreased in the whole skeletal muscle system (injection sites are not included). Consequently, it increased up to the control level after the sixth and the seventh injections. Among the studied organs (liver, kidneys, and spleen), Caspase-3 expression was revealed only in spleen. The expression had a direct dependence on the number of injections. Processes of iron elimination from preparation containing nanoparticles and their agglomerates had different intensity.

Beneficiary effect of nanosizing ferric pyrophosphate as food fortificant in iron deficiency anemia: evaluation of bioavailability, toxicity and plasma biomarker

NP-Fe₄(P₂O₇)₃significantly improved hemoglobin level in iron-deficient rats and Fetuin-B showed differential biological response across NP doses through plasma proteomics.

Effect of Aqueous Nanosuspensions of Clay Minerals on Broilers' Performance and Some Selected Antibody Titers

The effect of using different concentrations of aqueous nanosuspensions of clay minerals (1%, 1.5%, and 2%) offered at different periods of time (one time per one or two weeks) compared with tap-water with and without antibiotics on growth performance and some selected antibody titer was studied. The experiment lasted from 1 to 36 days of age. The statistical findings of the experiment prove that aqueous nanosuspension 1% offered one time per two weeks significantly improved feed conversion ratio (FCR). Meanwhile, aqueous nanosuspension 2% offered one time per two weeks significantly gave the same effect on live body weight (LBW) and body weight gain (BWG) as did antibiotics. Concerning the findings that pertain to immunity, antibody titer against the most infectious diseases [Newcastle (ND), infectious bronchitis (IB), and infectious bursal disease (IBD)] were significantly improved by offering aqueous nanosuspension 1.5% offered one time per one and two weeks, and aqueous nanosuspension 1% offered one time per one week, respectively.

Formation of ferric oxyhydroxide nanoparticles mediated by peptides in anchovy (Engraulis japonicus) muscle protein hydrolysate

Nanosized iron fortificants appear to be promising and can be synthesized in a greener way using peptides as biotemplates. Anchovy is a huge underdeveloped source of muscle protein that enhances human nonheme iron absorption. This paper shows that peptides in anchovy ( Engraulis japonicus ) muscle protein hydrolysate (AMPH) mediate the formation of monodispersed ferric oxyhydroxide nanoparticles (FeONPs) with diameters of 20-40 nm above pH 3.0. Peptides in AMPH nucleate iron through carboxyl groups and crystal growth then occur as a result of condensation of carboxylate-ligated hydroxide iron centers, yielding Fe-O-Fe cross-link bonds. Monomers of FeONPs are formed after steric obstruction of further crystal growth by peptide backbones with certain lengths and further stabilized by surface-adsorbed peptides. The iron-loading capacity of peptides in AMPH is up to 27.5 mg iron/g peptide. Overall, the present study provides a greener alternative route to the synthesis of FeONPs.

Biochemical alterations induced by acute oral doses of iron oxide nanoparticles in Wistar rats

Magnetic iron oxide nanoparticles with appropriate surface chemistry have been widely used with potential new applications in biomedical industry. Therefore, the aim of this study was to assess the size-, dose-, and time-dependent effects, after acute oral exposure to iron oxide-30 NP (Fe(2)O(3)-30), on various biochemical enzyme activities of clinical significances in a female Wistar rat model. Rats were exposed to three different doses (500, 1,000, and 2,000 mg/kg) of Fe(2)O(3)-30 and Fe(2)O(3)-Bulk along with control. Fe(2)O(3)-30 had no effect on growth, behavior, and nutritional performance of animals. Fe(2)O(3)-30 caused significant inhibition of acetylcholinestrase in red blood cells as well as in brains of treated rats. Further, more than 50% inhibition of total, Na(+)-K(+), Mg(2+), and Ca(2+)-ATPases activities, as observed in brains of exposed female rats, may be the result of disturbances in cellular physiology and the iono-regulatory process. Activation of the hepatotoxicity marker enzymes, aspartate aminotransferase and alanine aminotransferase, was recorded in serum and liver, whereas inhibition was observed in kidney. Similarly, enhancement of lactate dehydrogenase activity was observed in serum and liver; however, a decrease in enzyme levels was observed in kidneys of Fe(2)O(3)-30-treated rats. On the other hand, Fe(2)O(3)-Bulk did not depict any significant changes in these biochemical parameters, and alterations were near to control. Therefore, this study suggests that exposure to nanosize particles at acute doses may cause adverse changes in animal biochemical profiles. The use of the rat model signifies the correlation with the human system.

A brief review of the occurrence, use, and safety of food-related nanomaterials

Nanotechnology and nanomaterials have tremendous potential to enhance the food supply through novel applications, including nutrient and bioactive absorption and delivery systems; ingredient functionality; improved colors and flavors; microbial, allergen, and contaminant detection and control; and food packaging properties and performance. To determine the current state of knowledge regarding the safety of these potential uses of nanomaterials, an appraisal of the published literature on the safety of food-related nanomaterials was undertaken. A method of assessment of reliability of toxicology studies was developed to conduct this appraisal. The review of the toxicology literature on oral exposure to food-related nanomaterials found that the number of studies is limited. Exposure to nanomaterials in the human food chain may occur not only through intentional uses in food manufacturing, but also via uses in agricultural production and carry over from use in other industries. Although a number of analytical methods are useful in physicochemical characterization of manufactured nanomaterials, new methods may be needed to more fully detect and characterize nanomaterials incorporated into foods and in other media. There is a need for additional toxicology studies of sufficient quality and duration on different types of nanomaterials to further our understanding of the characteristics of nanomaterials that affect safety of oral exposure resulting from use in various food applications.

Homogeneous Iron Phosphate Nanoparticles by Combustion of Sprays

Low-cost synthesis of iron phosphate nanostructured particles is attractive for large scale fortification of basic foods (rice, bread, etc.) as well as for Li-battery materials. This is achieved here by flame-assisted and flame spray pyrolysis (FASP and FSP) of inexpensive precursors (iron nitrate, phosphate), solvents (ethanol), and support gases (acetylene and methane). The iron phosphate powders produced here were mostly amorphous and exhibited excellent solubility in dilute acid, an indicator of relative iron bioavailability. The amorphous and crystalline fractions of such powders were determined by X-ray diffraction (XRD) and their cumulative size distribution by X-ray disk centrifuge. Fine and coarse size fractions were obtained also by sedimentation and characterized by microscopy and XRD. The coarse size fraction contained maghemite Fe(2)O(3) while the fine was amorphous iron phosphate. Furthermore, the effect of increased production rate (up to 11 g/h) on product morphology and solubility was explored. Using increased methane flow rates through the ignition/pilot flame of the FSP-burner and inexpensive powder precursors resulted in also homogeneous iron phosphate nanoparticles essentially converting the FSP to a FASP process. The powders produced by FSP at increased methane flow had excellent solubility in dilute acid as well. Such use of methane or even natural gas might be economically attractive for large scale flame-synthesis of nanoparticles.