Challenging conventional risk assessment with respect to human exposure to multiple food contaminants in food: A case study using maize

Adverse effect propensity: A new feature of Gulf War illness predicted by environmental exposures

A third of 1990-1 Gulf-deployed personnel developed drug/chemical-induced multisymptom illness, "Gulf War illness" (GWI). Veterans with GWI (VGWI) report increased drug/exposure adverse effects (AEs). Using previously collected data from a case-control study, we evaluated whether the fraction of exposures that engendered AEs ("AE Propensity") is increased in VGWI (it was); whether AE Propensity is related to self-rated "chemical sensitivity" (it did); and whether specific exposures "predicted" AE Propensity (they did). Pesticides and radiation exposure were significant predictors, with copper significantly "protective"-in the total sample (adjusted for GWI-status) and separately in VGWI and controls, on multivariable regression. Mitochondrial impairment and oxidative stress (OS) underlie AEs from many exposures irrespective of nominal specific mechanism. We hypothesize that mitochondrial toxicity and interrelated OS from pesticides and radiation position people on the steep part of the curve of mitochondrial impairment and OS versus symptom/biological disruption, amplifying impact of new exposures. Copper, meanwhile, is involved in critical OS detoxification processes.

A PETAR method for risk assessment of human health and environment on the regional scale

Risk assessments are necessary to effectively reveal the state of the degradation of living environments on a regional scale. However, risk assessments are often limited by time, cost, and technology, which make conducting effective evaluations difficult. Thus, in this study, the procedure for ecological tiered assessment of risk (PETAR) method was used to analyze the human health and environmental risks in Daye, China. This method first used the United States Environmental Protection Agency's risk assessment approach to qualitatively determine the risk sources, pressures, receptors, and effect endpoints and constructed a conceptual model of threats to the human living environment. Each risk-prone subregion was then evaluated using the fuzzy logic method. Next, a quantitative assessment was conducted for the subregions with the most serious environmental degradation. Finally, quantitative analyses were performed to verify the original hypotheses. The results showed that the high-risk areas were distributed in the industrial regions of Daye, wherein mining and processing clusters and mining settlements are widespread and confirmed the locations of the particular subregions with the most serious human health and environmental risks. This study also validated the practicality of the PETAR method for human health risk assessments in mining areas with large-scale, multifactor, and multihazard paths. Integr Environ Assess Manag 2023;19:239-253. © 2022 SETAC.

Ochratoxin A Induces Steatosis via PPARγ-CD36 Axis

Ochratoxin A(OTA) is considered to be one of the most important contaminants of food and feed worldwide. The liver is one of key target organs for OTA to exert its toxic effects. Due to current lifestyle and diet, nonalcoholic fatty liver disease (NAFLD) has been the most common liver disease. To examine the potential effect of OTA on hepatic lipid metabolism and NAFLD, C57BL/6 male mice received 1 mg/kg OTA by gavage daily. Compared with controls, OTA increased lipid deposition and TG accumulation in mouse livers. In vitro OTA treatment also promoted lipid droplets accumulation in primary hepatocytes and HepG2 cells. Mechanistically, OTA prevented PPARγ degradation by reducing the interaction between PPARγ and its E3 ligase SIAH2, which led to activation of PPARγ signaling pathway. Furthermore, downregulation or inhibition of CD36, a known of PPARγ, alleviated OTA-induced lipid droplets deposition and TG accumulation. Therefore, OTA induces hepatic steatosis via PPARγ-CD36 axis, suggesting that OTA has an impact on liver lipid metabolism and may contribute to the development of metabolic diseases.

Metabolomics analysis underlay mechanisms in the renal impairment of mice caused by combination of aflatoxin M1 and ochratoxin A

Aflatoxin M1 (AFM1) and ochratoxin A (OTA) are pernicious mycotoxins widely co-existing in the environment. However, nephrotoxicity and underlying mechanism induced by AFM1 coupled with OTA still remain to be explored. In this study, CD-1 mice were treated with 3.5 mg/kg b.w. AFM1, OTA, and AFM1 + OTA for 35 days, and UPLC-MS-based metabolomics method was effectuated to investigate metabolomic profiles of mice kidney. Subsequent experiments on human renal proximal tubular (HK-2) cells were performed to dig out the causal connections between distinguished differential metabolites and nephrotoxicity. Compared with DMSO vehicle group, all three toxin treatments (AFM1 and OTA alone, and in combination) significantly reduced final body weight, and remarkably elevated the concentration of serum creatinine (SCr) and caused abnormal histological phenotypes (shown by histopathological slices). OTA, AFM1 + OTA but not AFM1 reduced the relative weight index of kidney. These phenotypic results indicated that AFM1 and OTA were both toxic to the body, and it seemed that OTA exhibited a notable impairment to kidney while AFM1 had similar but limited effect compared with OTA. Further metabolomics analysis showed that when AFM1 and OTA were combined together, OTA exerted dominant effect on the alteration of metabolic processes. There were few differences in the number of changed metabolites between OTA and AFM1 + OTA group. Among the differentially expressed metabolites affected by OTA, and AFM1 + OTA, lysophosphatidylcholines (LysoPCs) were identified as the main type with significant upregulation, in which LysoPC (16:0) accounted for the most prime proportion. Western blotting results of HK-2 cells showed that single OTA and AFM1 + OTA increased the apoptotic protein expressions of Bax, caspase 3 and PARP, and decreased the expression of Bcl-2; while AFM1 only raised the expression of caspase 3. LysoPC (16:0) but not LysoPC (18:1) lifted the protein level of caspase 3 and PARP in HK-2 cells, and reduced the level of Bcl-2. Taken together, this study is the first effort trying to assess nephrotoxicity of AFM1 with OTA, and we guessed that OTA had a more pronounced toxicity to kidney in contrast to AFM1. No obvious synergism between AFM1 and OTA was found to contribute to the occurrence or development of nephropathy. LysoPC (16:0) might be the pivotal metabolite in response to single OTA and combined AFM1 + OTA engendering renal injury.

Mycotoxins, Pesticide Residues, and Heavy Metals Analysis of Croatian Cereals

Cereals are still one of the most important food and feed sources, thus determining cereal’s safety, i.e., compliance with legislation, is extremely important. As systematic investigations of nowadays unavoidable secondary fungal metabolites and other common legally regulated contaminants occurrence in Croatian cereals are still lacking, this research aims to monitor the contamination levels of nation-wide crops by mycotoxins, pesticide residues, and heavy metals by employing UHPLC-MS/MS, GC-MS/MS, and atomic absorption spectrometer (AAS) validated analytical methods. The most common secondary fungal metabolites were found to be Fusarium mycotoxins, with DON being the most occurring present in 73.7% of the samples. At least one pesticide residue was found in 331.8% of the samples, and Hg and Cd were the most occurring heavy metals. A total of 8.5% of the samples was non-compliant to the European Union (EU) legislation for food regarding the found mycotoxins concentrations, 4.5% regarding pesticide residues and none regarding heavy metals. The unusual presence of certain pesticide residue and heavy metal indicates the importance of systematic control of the contaminant presence, in order to gather enough occurrence data for proper risk assessment that these contaminants represent for the consumer’s health.

Application of high-content screening for the study of hepatotoxicity: Focus on food toxicology

Safety evaluation of thousands of chemicals that are directly added to or come in contact with food is needed. Due to the central role of the liver in intermediary and energy metabolism and in the biotransformation of foreign compounds, the hepatotoxicity assessment is essential. New approach methodologies have been proposed for the safety evaluation of compounds with the idea of rapidly gaining insight into effects on biochemical mechanisms and cellular processes and screening large number of compounds. In this sense, high-content screening (HCS) is the application of automated microscopy and image analysis for better understanding of complex biological functions and mechanisms of toxicity. HCS multiparametric measurements have been shown to be a useful tool in early toxicity testing during drug development, but also in assessing the impact from food chemicals and environmental toxicants. Reviewing the use of cellular imaging technology in the safety evaluation of food-relevant chemicals offers evidence about the impact of this technology in safety assessment.

Magneto-controlled aptasensor for simultaneous detection of ochratoxin A and fumonisin B1 using inductively coupled plasma mass spectrometry with multiple metal nanoparticles as element labels

The simultaneous detection of multiple mycotoxins is important for food safety. Here, a magneto-controlled aptasensor for quantitative analysis of ochratoxin A (OTA) and fumonisin B1 (FB1) using inductively coupled plasma mass spectrometry (ICP-MS) with multiple metal nanoparticles as element labels was proposed. Firstly, the OTA aptamer (Apt1) and the FB1 aptamer (Apt2) immobilized on the magnetic beads (MBs) were hybridized with probe DNA1-CdSe quantum dots (pDNA1-QDs) and probe DNA2-Ag nanoparticles (pDNA2-Ag NPs) labels, producing the MBs-Apt1-pDNA1-QDs and MBs-Apt2-pDNA2-Ag NPs conjugates, respectively. Then, the MBs-Apt1-OTA and MBs-Apt2-FB1 conjugates were generated with the addition of targets, resulting the pDNA1-QDs and pDNA2-Ag NPs labels released into the solutions. Finally, the signal intensities of ¹¹¹Cd and ¹⁰⁷Ag were detected by ICP-MS, achieving limits of detection of 0.10 and 0.30 ng mL^-1 for OTA and FB1, respectively. The assay showed high specificity and succeeded in wheat flour. The method provides an ideal model for sensitive analysis of multiple mycotoxins in food samples.

Possible food safety hazards of ready-to-eat raw fish containing product (sushi, sashimi)

It is undeniable that with the popularity of sushi and sashimi over the last decade the consumption of raw fish has extremely increased. Raw fish is very appreciated worldwide and has become a major component of human diet because of its fine taste and nutritional properties. Possible hazards concerning fish safety and quality are classified as biological and chemical hazards. They are contaminants that often accumulate in edible tissue of fish and transmit to humans via the food chain affecting the consumer's health. Although their concentration in fish and fishery products are found at non-alarming level of a daily basis period, they induce hazardous outcome on human health due to long and continuous consumption of raw fish. Regular sushi and sashimi eaters have to be aware of the contaminants found in the other components of their dish that often add up to acceptable residue limits found in fish. Hence, there is the urge for effective analytical methods to be developed as well as stricter regulations to be put in force between countries to monitor the safety and quality of fish for the interest of public health.

Enhancing Food Safety through Adoption of Long-Term Technical Advisory, Financial, and Storage Support Services in Maize Growing Areas of East Africa

Grain production and storage are major components in food security. In the ancient times, food security was achieved through gathering of fruits, grains, herbs, tubers, and roots from the forests by individual households. Advancements in human civilization led to domestication of crops and a need to save food for not only a household, but the nation. This extended need for food security led to establishment of national reservoirs for major produces and this practice varies greatly in different states. Each of the applied food production, handling, and storage approaches has its benefits and challenges. In sub-Saharan Africa, several countries have a public funded budget to subsidize production costs, to buy grains from farmers, and to store the produce for a specific period and/or until the next harvests. During the times of famine, the stored grains are later sold at subsidized prices or are given for free to the starving citizens. If there is no famine, the grain is sold to retailers and/or processors (e.g., millers) who later sell it to the consumers. This approach works well if the produce (mainly grain) is stored under conditions that do not favor growth of molds, as some of these microbes could contaminate the grain with toxic and carcinogenic metabolites called mycotoxins. Conditions that alleviate contamination of grains are required during production, handling, and storage. Most of the grain is produced by smallholder farmers under sub-optimal conditions, making it vulnerable to colonization and contamination by toxigenic fungi. Further, the grain is stored in silos at large masses, where it is hard to monitor the conditions at different points of these facilities, and hence, it becomes vulnerable to additional contamination. Production and storage of grain under conditions that favor mycotoxins poses major food health and safety risks to humans and livestock who consume it. This concept paper focuses on how establishment of a local grain production and banking system (LGPBS) could enhance food security and safety in East Africa. The concept of LGPBS provides an extension of advisory and finance support within warehouse receipt system to enhance grain production under optimal conditions. The major practices at the LGPBS and how each could contribute to food security and safety are discussed. While the concept paper gives more strength on maize production and safety, similar practices could be applied to enhance safety of other grains in the same LGPBS.

Assessment of Toxic Effects of Ochratoxin A in Human Embryonic Stem Cells

Ochratoxin A (OTA) is a mycotoxin produced by different Aspergillus and Penicillium species, and it is considered a common contaminant in food and animal feed worldwide. On the other hand, human embryonic stem cells (hESCs) have been suggested as a valuable model for evaluating drug embryotoxicity. In this study, we have evaluated potentially toxic effects of OTA in hESCs. By using in vitro culture techniques, specific cellular markers, and molecular biology procedures, we found that OTA produces mild cytotoxic effects in hESCs by inhibiting cell attachment, survival, and proliferation in a dose-dependent manner. Thus, we suggest that hESCs provide a valuable human and cellular model for toxicological studies regarding preimplantation stage of human fetal development.

Administration of Momordica charantia Enhances the Neuroprotection and Reduces the Side Effects of LiCl in the Treatment of Alzheimer's Disease

Recently, the use of natural food supplements to reduce the side effects of chemical compounds used for the treatment of various diseases has become popular. Lithium chloride (LiCl) has some protective effects in neurological diseases, including Alzheimer’s disease (AD). However, its toxic effects on various systems and some relevant interactions with other drugs limit its broader use in clinical practice. In this study, we investigated the in vitro and in vivo pharmacological functions of LiCl combined with Momordica charantia (MC) in the treatment of AD. The in vitro results show that the order of the neuroprotective effect is MC5, MC3, MC2, and MC5523 under hyperglycemia or tau hyperphosphorylation. Therefore, MC5523 (80 mg/kg; oral gavage) and/or LiCl (141.3 mg/kg; intraperitoneal injection) were applied to ovariectomized (OVX) 3×Tg-AD female and C57BL/6J (B6) male mice that received intracerebroventricular injections of streptozotocin (icv-STZ, 3 mg/kg) for 28 days. We found that the combined treatment not only increased the survival rate by reducing hepatotoxicity but also increased neuroprotection associated with anti-gliosis in the icv-STZ OVX 3×Tg-AD mice. Furthermore, the cotreatment with MC5523 and LiCl prevented memory deficits associated with reduced neuronal loss, gliosis, oligomeric Aβ level, and tau hyperphosphorylation and increased the expression levels of synaptic-related protein and pS9-GSK3β (inactive form) in the icv-STZ B6 mice. Therefore, MC5523 combined with LiCl could be a potential strategy for the treatment of AD.

Rat feeding trials: A comprehensive assessment of contaminants in both genetically modified maize and resulting pellets

We analyzed a comprehensive set of contaminants in MON810 and NK603 genetically modified (GM) maize, and their non-GM counterparts, used in a rat feeding study (the GMO90 + project). Both the maize grains and the manufactured pellets were characterized. Only minor differences in contaminant levels between GM and corresponding non-GM harvests were evidenced. Fumonisin and deoxynivalenol mycotoxins were the pollutants present in the highest amounts, with concentrations that were however largely below acceptance reference values. Our data reporting slightly lower levels of fumonisin in MON810 compared to its non-GM counterpart corroborate the lower susceptibility of insect resistant Bt maize to fumonisin-producing fungi. Traces of glyphosate (0.016 mg/kg) were evidenced in grains from NK603 treated crops. Regarding the pellets, analysis of more than 650 potentially toxic substances revealed low amounts of various mycotoxins, pesticides and heavy metals. Concentrations of contaminants quantified in the pellets were however far below the maximum level of residues values set by regulatory agencies, and no substantial differences in contaminants between GM and non-GM pellets were observed. Moreover, when comparing the contamination status of grains and pellets, we demonstrate yet again that characterizing the grains is actually not sufficient to foresee the quality of the produced pellets.

Analysis of the interactions between environmental and food contaminants, cadmium and deoxynivalenol, in different target organs

Cadmium (Cd), a common and widespread toxic heavy metal, and mycotoxins such as deoxynivalenol (DON) are frequent contaminants of the food supply. Most of the data on their toxicity concern their effects when present alone. However, consumers can be exposed to a cocktail of DON and Cd. To improve the understanding of their combined toxicity, the effects of DON and Cd alone or in combination were investigated in different human cell lines from the kidney (HEK-293), intestine (Caco-2), blood (HL-60) and liver (HepG2). Cytotoxicity was assessed through ATP measurement and types of interactions determined by the Isobologram-Combination index method. HEK-293 cells were exposed to increasing doses of DON, Cd and their combination at different ratios (DON/Cd of 2/1; 1/1; 1/2 and 1/8). Regardless of the ratio, the type of interaction observed in HEK-293 cells ranged from moderate antagonism to nearly additive with increasing cytotoxicity. In Caco-2 cells, the interactions ranged from nearly additive to antagonism whatever the ratio. At ratio 1/1, in HL-60 and HepG2 cells, interactions ranged from synergy to antagonism depending on the cytotoxicity level. Using human cells lines, this study indicates that the consequences of combined exposure to environmental and food contaminants are specific to the target organ. Further studies are needed to confirm these data in vivo.

Evidence of in vitro metabolic interaction effects of a chlorfenvinphos, ethion and linuron mixture on human hepatic detoxification rates

General population exposure to pesticides mainly occurs via food and water consumption. However, their risk assessment for regulatory purposes does not currently consider the actual co-exposure to multiple substances. To address this concern, relevant experimental studies are needed to fill the lack of data concerning effects of mixture on human health. For the first time, the present work evaluated on human microsomes and liver cells the combined metabolic effects of, chlorfenvinphos, ethion and linuron, three pesticides usually found in vegetables of the European Union. Concentrations of these substances were measured during combined incubation experiments, thanks to a new analytical methodology previously developed. The collected data allowed for calculation and comparison of the intrinsic hepatic clearance of each pesticide from different combinations. Finally, the results showed clear inhibitory effects, depending on the association of the chemicals at stake. The major metabolic inhibitor observed was chlorfenvinphos. During co-incubation, it was able to decrease the intrinsic clearance of both linuron and ethion. These latter also showed a potential for metabolic inhibition mainly cytochrome P450-mediated in all cases. Here we demonstrated that human detoxification from a pesticide may be severely hampered in case of co-occurrence of other pesticides, as it is the case for drugs interactions, thus increasing the risk of adverse health effects. These results could contribute to improve the current challenging risk assessment of human and animal dietary to environmental chemical mixtures.

Determination of Aflatoxin M1 and Heavy Metals in Infant Formula Milk Brands Available in Pakistani Markets

Aflatoxin M₁ (AFM₁) after its bioconversion from aflatoxin B₁ in animal liver becomes the part of milk while heavy metals get entry into milk and milk products during handling in the supply chain. Aflatoxin M₁ and heavy metals being toxic compounds are needed to be monitored continuously to avoid any ailments among consumers of foods contaminated with such toxicants. Thirteen commercially available infant formula milk (IFM) brands available in Pakistani markets were analyzed for the quantitative determination of AFM₁ and heavy metals through ELISA and atomic absorption spectrophotometer, respectively. AFM₁ was found positive in 53.84% samples while 30.76% samples were found exceeding the maximum EU limit i.e. 0.025 μg/kg for AFM₁ in IFM. Heavy metals lead (Pb) and cadmium (Cd) were found below the detection limits in any of the sample, whereas the concentrations of iron (Fe), zinc (Zn) and nickel (Ni) ranged between 45.40-97.10, 29.72-113.50 and <0.001-50.90 μg/kg, respectively. The concentration of Fe in all the tested brands was found in normal ranges while the concentrations of Zn and Ni were found exceeding the standard norms. Elevated levels of AFM₁, Zn and Ni in some of the tested IFM brands indicated that a diet completely based on these IFM brands might pose sever health implications in the most vulnerable community i.e., infants.

Identification of chemical mixtures to which Canadian pregnant women are exposed: The MIREC Study

Depending on the chemical and the outcome, prenatal exposures to environmental chemicals can lead to adverse effects on the pregnancy and child development, especially if exposure occurs during early gestation. Instead of focusing on prenatal exposure to individual chemicals, more studies have taken into account that humans are exposed to multiple environmental chemicals on a daily basis. The objectives of this analysis were to identify the pattern of chemical mixtures to which women are exposed and to characterize women with elevated exposures to various mixtures. Statistical techniques were applied to 28 chemicals measured simultaneously in the first trimester and socio-demographic factors of 1744 participants from the Maternal-Infant Research on Environment Chemicals (MIREC) Study. Cluster analysis was implemented to categorize participants based on their socio-demographic characteristics, while principal component analysis (PCA) was used to extract the chemicals with similar patterns and to reduce the dimension of the dataset. Next, hypothesis testing determined if the mean converted concentrations of chemical substances differed significantly among women with different socio-demographic backgrounds as well as among clusters. Cluster analysis identified six main socio-demographic clusters. Eleven components, which explained approximately 70% of the variance in the data, were retained in the PCA. Persistent organic pollutants (PCB118, PCB138, PCB153, PCB180, OXYCHLOR and TRANSNONA) and phthalates (MEOHP, MEHHP and MEHP) dominated the first and second components, respectively, and the first two components explained 25.8% of the source variation. Prenatal exposure to persistent organic pollutants (first component) were positively associated with women who have lower education or higher income, were born in Canada, have BMI ≥25, or were expecting their first child in our study population. MEOHP, MEHHP and MEHP, dominating the second component, were detected in at least 98% of 1744 participants in our cohort study; however, no particular group of pregnant women was identified to be highly exposed to phthalates. While widely recognized as important to studying potential health effects, identifying the mixture of chemicals to which various segments of the population are exposed has been problematic. We present an approach using factor analysis through principal component method and cluster analysis as an attempt to determine the pregnancy exposome. Future studies should focus on how to include these matrices in examining the health effects of prenatal exposure to chemical mixtures in pregnant women and their children.

Challenges in risk assessment of multiple mycotoxins in food

Most fungi are able to produce several mycotoxins simultaneously and, consequently, to contaminate a wide variety of foodstuffs. Therefore, the risk of human co-exposure to multiple mycotoxins is real, raising a growing concern about their potential impact on human health. Besides, government and industry regulations are usually based on individual toxicities, and do not take into account the complex dynamics associated with interactions between co-occurring groups of mycotoxins. The present work assembles, for the first time, the challenges posed by the likelihood of human co-exposure to these toxins and the possibility of interactive effects occurring after absorption, towards knowledge generation to support a more accurate human risk assessment. Regarding hazard assessment, a physiologically-based framework is proposed in order to infer the health effects from exposure to multiple mycotoxins in food, including knowledge on the bioaccessibility, toxicokinetics and toxicodynamics of single and combined toxins. The prioritisation of the most relevant mixtures to be tested under experimental conditions that attempt to mimic human exposure and the use of adequate mathematical approaches to evaluate interactions, particularly concerning the combined genotoxicity, were identified as the main challenges for hazard assessment. Regarding exposure assessment, the need of harmonised food consumption data, availability of multianalyte methods for mycotoxin quantification, management of left-censored data, use of probabilistic models and multibiomarker approaches are highlighted, in order to develop a more precise and realistic exposure assessment. To conclude, further studies on hazard and exposure assessment of multiple mycotoxins, using harmonised methodologies, are crucial towards an improvement of data quality and a more reliable and robust risk characterisation, which is central for risk management and, consequently, to prevent mycotoxins-associated adverse effects. A deep understanding of the nature of interactions between multiple mycotoxins will contribute to draw real conclusions on the health impact of human exposure to mycotoxin mixtures.

Aflatoxin M1 cytotoxicity against human intestinal Caco-2 cells is enhanced in the presence of other mycotoxins

Aflatoxin M1 (AFM1), a class 2B human carcinogen, is the only mycotoxin with established maximum residue limits (MRLs) in milk. Toxicological data for other mycotoxins in baby food, containing cereals and milk, either in isolation or in combination with AFM1, are sparse. The aim of this study was to investigate the cytotoxicity of AFM1, ochratoxin A (OTA), zearalenone (ZEA), and α-zearalenol (α-ZOL), individually and in combinations, in human Caco-2 cells. The tetrazolium salt (MTT) assay demonstrated that (i) OTA and AFM1 had similar cytotoxicity, which was higher than that of ZEA and α-ZOL, after a 72 h exposure; and (ii) the quaternary combination had the highest cytotoxicity, followed by tertiary and binary combinations and individual mycotoxins. Isobologram analysis indicated that the presence of OTA, ZEA, and/or α-ZOL with AFM1 led to additive and synergistic cytotoxicity in most combinations. The cytotoxicity of OTA was similar to that of AFM1, suggesting that OTA in food poses a health risk to consumers. Furthermore, AFM1 cytotoxicity increased dramatically in the presence of OTA, ZEA, and/or α-ZOL (p < 0.01), indicating that the established MRLs for AFM1 should be re-evaluated considering its frequent co-occurrence with other mycotoxins in baby food which contains milk and cereals.

On-off Bodipy chemosensor for recognition of iron(III) ion based on the inner filter effect and its applications in cellular and bacterial imaging

One strong fluorescent Bodipy-containing derivative was synthesized and characterized using ¹ H NMR, electrospray ionization mass spectrometry and elemental analysis. Its electrochemical and photophysical properties were investigated. In addition, the Bodipy derivative could be used as an on-off fluorescent probe for the detection of Fe³⁺ ions based on the inner filter effect because the absorption band of the Fe³⁺ ion overlaps the excitation band of Bodipy very well upon irradiation with UV light. Furthermore, the Bodipy-based sensor has obvious advantages including simplicity, rapid response, high selectivity, sensitivity and a detection limit of 1.2 μmol/L, and has been demonstrated in real water samples including tap water, mineral water and water from Lake Tai. Moreover, the fluorescent probe could also be used as a probe for the determination of Fe³⁺ in cellular and bacterial imaging. Copyright © 2016 John Wiley & Sons, Ltd.

Glutathione-directed synthesis of Cr(vi)- and temperature-responsive fluorescent copper nanoclusters and their applications in cellular imaging

Highly red luminescent GSH–Cu nanoclusters were synthesized and could be used as nanosensors for Cr(vi) ions and temperature.

Crosstalk-eliminated quantitative determination of aflatoxin B1-induced hepatocellular cancer stem cells based on concurrent monitoring of CD133, CD44, and aldehyde dehydrogenase1

Cancer stem cells (CSCs), known as tumor initiating cells, have become a critically important issue for cancer therapy. Although much research has demonstrated the induction of hepato cellular carcinoma by aflatoxin B1, the formation of hepatocellular CSCs and their quantitative determination is hardly reported. In this work, it was found that hepatocellular CSCs were produced from HepG2 cells by aflatoxin B1-induced mutation, and their amount was quantitatively determined using crosstalk-eliminated multicolor cellular imaging based on quantum dot (Qdot) nanoprobes and an acousto-optical tunable filter (AOTF). Hepatocellular CSCs were acquired via magnetic bead-based sorting and observed using concurrent detection of three different markers: CD133, CD44, and aldehyde dehydrogenase1 (ALDH1). The DNA mutation of HepG2 cells caused by aflatoxin B1 was quantitatively observed via absorbance spectra of aflatoxin B1-8, 9-epoxide-DNA adducts. The percentages of hepatocellular CSCs formed in the entire HepG2 cells were determined to be 9.77±0.65%, 10.9±1.39%, 11.4±1.32%, and 12.8±0.7%, respectively, at 0 μM, 5 μM, 10 μM, and 20 μM of aflatoxin B1. The results matched well with those obtained utilizing flow cytometry. This study demonstrates that aflatoxin mediated mutation induced the conversion of hepatic cancer cell to hepatic CSCs by using a Qdot based constructed multicolor cellular imaging system.