Smartphone-based magneto-immunosensor on carbon black modified screen-printed electrodes for point-of-need detection of aflatoxin B1 in cereals.

Considering the complexities and speed of modern food chains, there is an increasing demand for point-of-need detection of food contaminants, particularly highly regulated chemicals and carcinogens such as aflatoxin B1. We report a user-friendly smartphone-based magneto-immunosensor on carbon black modified electrodes for point-of-need detection of aflatoxin B1 in cereals. For buffered analyte solutions and a corn extract sample, the assay demonstrated a low limit of detection of 13 and 24 pg/mL, respectively. The assay was also highly reproducible, exhibiting mean relative standard deviations of 3.7% and 4.0% for the buffered analyte and corn extract samples. The applicability of the assay was validated on the basis of EU guidelines and the detection capability was lower than or equal to 2 µg/kg, which is the EU maximum residue limit for aflatoxin B1 in cereals. False-positive and false-negative rates were less than 5%. Additionally, an open-source android application, AflaESense, was designed to provide a simple interface that displays the result in a traffic-light-type format, thus minimizing user training and time for data analysis. AflaESense was used for smartphone-based screening of spiked corn samples containing aflatoxin B1 (0.1, 2, and 10 ng/mL), and naturally contaminated corn containing 0.15 ng aflatoxin B1/mL. The measured values were in close agreement with spiked concentrations (r2 = 0.99), with recovery values ranging between 80 and 120%. Finally, contaminated samples correctly triggered a red alert while the non-contaminated samples led to the display of a green color of AflaESense. To the best of our knowledge, this is the first smartphone-based electrochemical system effective for screening samples for contamination with aflatoxin B1.

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.

Induction of complementary function reductase enzymes in colon cancer cells by dithiole-3-thione versus sodium selenite.

Cellular induction of reductase enzymes can alter the susceptibility of cells toward drugs and chemicals. In this study, we compared the capacity of a single dose of sodium selenite and 3H-1,2-dithiole-3-thione (D3T) to influence the drug-relevant reducing capacity of HT29 cells over time, and defined the protein-specific contribution to this activity on the basis of selected reaction monitoring mass spectrometry. Thioredoxin reductase 1 (TrxR1) protein levels and activity were inducible up to 2.2-fold by selenium. In contrast, selenium had only a minor influence on prostaglandin reductase 1 (PTGR1) and NAD(P)H: quinone oxidoreductase 1 (NQO1) activity and protein levels. D3T, a strong Nrf2 inducer, induced all the reductases and additionally increased the cytotoxicity of hydroxymethylacylfulvene, a bioreductive DNA-alkylating drug. The data and experimental approaches allow one to define induction potency for reductase enzymes PTGR1, TrxR1, and NQO1 in HT29 cells and link these to changes in drug cytotoxicity.

Transcriptomic responses of cancerous and noncancerous human colon cells to sulforaphane and selenium.

Diets enriched with bioactive food components trigger molecular changes in cells that may contribute to either health-promoting or adverse effects. Recent technological advances in high-throughput data generation allow for observing systems-wide molecular responses to cellular perturbations with nontoxic and dietary-relevant doses while considering the intrinsic differences between cancerous and noncancerous cells. In this chemical profile, we compared molecular responses of the colon cancer cell line HT29 and a noncancerous colon epithelial cell line (HCEC) to two widely encountered food components, sulforaphane and selenium. We conducted this comparison by generating new transcriptome data by microarray gene-expression profiling, analyzing them statistically on the single gene, network, and functional pathway levels, and integrating them with protein expression data. Sulforaphane and selenium, at doses that did not inhibit the growth of the tested cells, induced or repressed the transcription of a limited number of genes in a manner distinctly dependent on the chemical and the cell type. The genes that most strongly responded in cancer cells were observed after treatment with sulforaphane and were members of the aldo-keto reductase (AKR) superfamily. These genes were in high agreement in terms of fold change with their corresponding proteins (correlation coefficient r(2) = 0.98, p = 0.01). Conversely, selenium had little influence on the cancer cells. In contrast, in noncancerous cells, selenium induced numerous genes involved in apoptotic, angiogenic, or tumor proliferation pathways, whereas the influence of sulforaphane was very limited. These findings contribute to defining the significance of cell type in interpreting human cellular transcriptome-level responses to exposures to natural components of the diet.

Identification of cyanidin glycosides as constituents of freeze-dried black raspberries which inhibit anti-benzo[a]pyrene-7,8-diol-9,10-epoxide induced NFkappaB and AP-1 activity.

Dietary freeze-dried black raspberries inhibit tumor induction by N-nitrosomethylbenzylamine in the rat esophagus, but the constituents responsible for this chemopreventive activity have not been identified. We fractionated freeze-dried black raspberries and used mouse epidermal JB6 Cl 41 cells stably transfected with either a nuclear factor kappa B (NFkappaB)- or an activator protein 1 (AP-1)-luciferase reporter, and treated with racemic anti-benzo[a]pyrene-7,8-diol-9,10-epoxide (BPDE), to assess the inhibitory effects of the fractions. The ethanol and water extracts of the freeze-dried black raspberries had inhibitory activity and these extracts were fractionated by HPLC to give several bioactive fractions. Further HPLC analysis yielded multiple subfractions, some of which inhibited BPDE-induced NFkappaB activity. Major constituents of the most active subfractions were identified by their spectral properties and in comparison with standards as cyanidin-3-O-glucoside, cyanidin 3-O-(2(G)-xylosylrutinoside) and cyanidin 3-O-rutinoside. Analysis of freeze-dried black raspberries indicated that these three components comprised approximately 3.4% of the material by dry weight. Consistent with these results, standard cyanidin-3-O-glucoside and cyanidin chloride were also good inhibitors of BPDE-induced NFkappaB activity. The results of this study demonstrate that cyanidin glycosides of freeze-dried black raspberries are bioactive compounds which could account for at least some of the chemopreventive activity observed in animal models.