Comparison of Translocation and Transformation from Soil to Rice and Metabolism in Rats for Four Arsenic Species

Ultrasensitive Electrochemiluminescence Sensor Utilizing Aggregation-Induced Emission Active Probe for Accurate Arsenite Quantification in Rice Grains

Arsenic (As) constitutes a substantial threat to global ecosystems and public health. An accurate quantification of inorganic arsenite (As(III)) in rice grains is crucial for ensuring food safety and human well-being. Herein, we constructed an electrochemiluminescence (ECL) biosensor utilizing aggregation-induced emission (AIE) active Pdots for the sensitive detection of As(III) in rice. We synthesized tetraphenylethylene-based AIE-active Pdots, exhibiting stable and highly efficient ECL emission in their aggregated states. Owing to the overlap of spectra, we employed an electrochemiluminescence resonance energy transfer (ECL-RET) system, with the Pdots as the donor and black hole quencher (BHQ) as the acceptor. Upon the introduction of As(III), the conformational changes of As(III)-specific aptamer could trigger the detachment of BHQ-labeled DNA aptamer from the electrode surface, leading to the recovery of the ECL signal. The target-induced "signal-on" bioassay enabled the sensitive and specific detection of As(III) with a linear range of 10 pM to 500 nM, with an ultralow limit of detection (LOD) of 5.8 pM/0.4 ppt. These values significantly surpass those of existing sensors designed for As(III) quantification in rice. Furthermore, by employing amylase hydrolysis for efficient extraction, we successfully applied our sensor to measure As(III) in actual rice samples sourced from diverse regions of China. The results obtained using our sensor were in close agreement with those derived from the reference method of HPLC-ICP-MS. This study not only presents a sensitive and reliable method for detecting arsenite but also underscores its potential applications in enhancing food safety, agriculture practices, and environmental monitoring.

Comparative evaluation of in vivo relative bioavailability and in vitro bioaccessibility of arsenic in leafy vegetables and its implication in human exposure assessment

Arsenic (As) contamination in vegetables is a severe threat to human health. However, the evaluation of As relative bioavailability (As-RBA) or bioaccessibility in vegetables is still unexplored. The study sought to evaluate the As-RBA in commonly consumed ten leaf vegetables collected from As-polluted farmlands. Additionally, the As-RBA was determined using rat bioassay and compared with As bioaccessibility through five commonly used in vitro methods, including UBM (Unified BARGE Method), SBRC (Solubility Bioavailability Research Consortium), DIN (Deutsches Institut für Normung e.V.), IVG (In Vitro Gastrointestinal), and PBET (Physiologically Based Extraction Test). Results showed that the As-RBA values were 14.3-54.0% among different vegetables. Notably, significant in vivo-in vitro correlations (IVIVC) were observed between the As-RBA and the As bioaccessibility determined by the PBET assay (r² = 0.763-0.847). However, the other assays (r² = 0.417-0.788) showed a comparatively weaker relationship. The estimation of As-RBA using derived IVIVC to assess As exposure risk via vegetable consumption confirmed that As exposure risk based on As-RBA was lower than that the total As concentrations. Therefore, it was concluded that PBET could better predict the As-RBA in vegetables than other in vitro assays. Furthermore, As-RBA values should be considered for accurate health risk assessment of As in vegetables.

Distribution of arsenic species and pathological characteristics of tissues of the mice fed with arsenic-supplemented food simulating rice

The exposure and harm of arsenic have attracted wide attention. Rice is an arsenic-rich crop. The purpose of this study was to learn the distribution of arsenic species and the pathological changes in tissues of mice exposed to arsenic-supplemented food simulating rice. Test groups of mice were orally exposed with prepared arsenic feeds supplemented with four arsenic species (arsenite iAs^III, arsenate iAs^V, monomethylarsonate MMA, and dimethylarsinate DMA) at three doses (total As concentration: 0.91, 9.1 and 30 μg/g), which simulated the arsenic species ratio in rice. After 112 days, the concentrations of the arsenic species in the spleen, thymus, heart, skin and hair were detected, and histopathology of the spleen, heart and skin was observed. Each arsenic species was detected and their total concentration increased in a dose-dependent manner with a few exceptions. One interesting phenomenon is that ratio of the organic arsenic to inorganic arsenic also increased in a dose-dependent manner. For the other, the order of tissues from high to low arsenic concentration was the same in the medium- and high-dose groups. The histopathological sections of the spleen, heart and skin showed dose-dependent debilitating alterations in tissue architecture. Hyperplasia, hyaline degeneration and sclerosis of fibrous connective tissue occurred in the spleen. Myocardial cell atrophy and interstitial edema occurred in the heart. Hyperpigmentation, hyperkeratosis and atypia of basal cells occurred in the skin. In summary, the long-term intake of high arsenic rice has a health risk. Further studies are needed to assess it.

Metabolic and residual characteristic of different arsenic species contained in laver during mouse digestion

Laver is one of the major arsenic contributors to human diets. The study on metabolic and residual characteristic of each arsenic species contained in laver is important to scientifically assess the intake risk of arsenic in the laver. The metabolic and residual characteristic of main arsenic species in laver, namely arsenate [As(V)], dimethylarsinic acid [DMA(V)] and two arsenosugars, was investigated by mouse experiments in this study. The results showed that the intake of higher-dose laver did not lead to a notable increase of As(V) concentration in mouse muscle/organs and feces. In contrast, DMA(V) excretion in feces and DMA(V) residue in muscle/organs showed a close correlation with laver-dose intake. Most DMAsSugarMethoxy was translated into other arsenic species and then was together excreted out via mouse feces; two dominant arsenic species, arsenosugar DMAsSugarMethoxy and DMAsSugarPhosphate, were not detected in mouse muscle/organs after 20-Day or 30-Day feeding whether in lower-dose laver groups containing 1/36 (mass ratio) of the laver in mouse feed or higher-dose laver groups containing 1/6 (mass ratio) of the laver in mouse feed. About 65-77% of total arsenic digested by mouse was excreted out via feces; only 0.12-0.78% of it was accumulated in mouse organs/muscle. The results of this study provided valuable knowledge for comprehending the stability and metabolic characteristics of different arsenic species from Fujian laver in vivo, also for more scientifically assessing the intake risk of arsenic in laver.

A Novel Pretreatment Device Integrating Magnetic-Assisted Dispersive Extraction and Ultrasonic Spray Separation for Speciation Analysis of Arsenic in Whole Blood by Ion Chromatography-Inductively Coupled Plasma-Mass Spectrometry

Speciation analysis of arsenic in blood is essential for identifying and quantifying the exposure of arsenic and studying the metabolism and toxicity of arsenic. Herein, a novel pretreatment device is rationally designed and used for speciation analysis of arsenic in whole blood by ion chromatography-inductively coupled plasma-mass spectrometry (IC-ICP-MS). The sample centrifuge tubes containing blood, reagents, and a magnetic stir bar are placed on the fidget spinner of the pretreatment device. When flicking the fidget spinner rotation with the finger, the magnetic stir bar in the tube rotates in three dimensions under the magnetic field, thereby assisting dispersive extraction of arsenic species by the mixing of blood with reagents. Afterward, the arsenic extract is separated in situ from the blood matrix using an ultrasonic spray sheet covered with a filter and ultrafiltration membrane, which is directly used for subsequent IC-ICP-MS analysis. For 100 μL of blood, the whole pretreatment operation can be completed within 10 min. With As(III), As(V), MMA, and DMA in blood as analytes, the use of the present pretreatment device will hardly lead to the loss and transformation of arsenic species, and the extraction efficiency of the total arsenic is more than 96%. When the pretreatment device is coupled to IC-ICP-MS, the detection limits of four arsenic species in whole blood are 0.017-0.023 μg L^-1, and precisions are within 2.3-4.2%. This pretreatment device provides a simple, fast, efficient, and low-cost tool for extraction and separation of arsenic species in whole blood, opening a new idea for the pretreatment of complex samples.

DNA-Gated Graphene Field-Effect Transistors for Specific Detection of Arsenic(III) in Rice

As one of the most toxic forms of arsenic, inorganic As(III) is easy to accumulate in rice, leading to severe public health problems. Effective control of As(III) requires the development of fast analytical methods for its detection with high sensitivity and specificity. Toward this end, in this work, we report the fabrication of an As(III) electrochemical sensor based on a solution-gated graphene transistor (SGGT) platform with a novel sensing mechanism. The gold gate electrode of the SGGT was modified with DNA probes and then blocked with bovine serum albumin (BSA). The specific interaction between As(III) and gold disrupted the adsorption states of DNA probes, redistributing surface charges on the gate electrode, further leading to potential drop changes at the interfaces of the gate electrode and graphene active layer. This new mechanism based on DNA-charge-redistribution-induced SGGT current responses (denoted as "DNA-SGGT") was found to greatly improve the selectivity of the sensor: the response of DNA-SGGT to As(III) was effectively enhanced fourfold, while to other interfering cations, it was significantly reduced. The optimized sensor showed a detection limit as low as 5 nM with superior selectivity to As(III). The as-prepared DNA-SGGT-based sensor has also been successfully applied to the detection of As(III) in practical rice samples with a high recovery rate, showing great potential for heavy metal detection in many types of food samples.

The mycobiome in murine intestine is more perturbed by food arsenic exposure than in excreted feces

Arsenic is a global pollutant that can accumulate in rice and has been confirmed to disturb the gut microbiome. By contrast, the influence on the gut mycobiome is seldom concerned because fungi comprise a numerically small proportion of the whole gut microcommunity. To expand the detection of the mycobiome in different gut sections of mammals and investigate the influence of food arsenic on the gut mycobiome in the digestive tract, we treated mice with feeds containing different compositions of arsenic species (7.3% sodium arsenate, 72.7% sodium arsenite, 1.0% sodium monomethylarsonate, and 19.0% sodium dimethylarsinate) in rice at a total arsenic dose of 30 mg/kg. After 60 days of exposure, the feces of four different sites, the ileum, cecum, colon, and excreted feces, were collected and analyzed by internal transcribed spacer gene sequencing. Among the samples, the major fungal phyla were Ascomycota, Basidiomycota, and Zygomycota; the top 10 fungal genera were Aspergillus, Verticillium, Penicillium, Cladosporium, Alternaria, Fusarium, Ophiocordyceps, Trametes, Mucor, and Nigrospora. In control mice, along the murine digestive tract, the mycobial richness and composition were significantly changed; Aspergillus and Penicillium possessed the higher ability to be stabilized in the murine gut, and larger proportions of positive correlations were observed among the major fungi. After arsenic exposure, the fungal composition was more disturbed in the intestinal tract than in feces. Along the digestive tract, arsenic can trigger larger mycobial variations, and the sensitivities of major fungi to arsenic were changed. Thus, the murine intestinal spatial mycobiota are more perturbed than excreted fecal mycobiota after food arsenic exposure. Feces are insufficient to be selected as a representative of the gut mycobiota in arsenic exposure studies.

Comparison of bioaccessibility and relative bioavailability of arsenic in rice bran: The in vitro with PBET/SHIME and in vivo with mice model

Rice bran, a super food or health food supplement, contains high arsenic (As) levels. However, the evaluation of relative bioavailability (RBA) or bioaccessibility (BA) is limited in the rice bran. In this study, the As-RBA in rice bran was determined based on mice model and compared to As-BA using in vitro methods. The As-BA from rice bran-amended feed in the gastric, small intestinal, and colon phases were 33.1-56.4%, 50.5-75.6%, and 35.5-71.4%, respectively. The As-BA was adversely associated with bioaccessible Ca and Fe concentrations in the gastrointestinal phases. Similarly, the As-RBA was significant negative relative with Ca, Fe, and Zn concentrations. The As-RBA values were 37.9-65.5%, 41.5-75.6% and 38.7-71.5% based on liver, kidneys, and combined endpoint (liver plus kidneys), respectively. The in vitro-in vivo correlations (IVIVCs) in the gastric (R² = 0.392) and colon (R² = 0.362) phases were weak. While the IVIVC (R² = 0.544) in the small intestinal phase was stronger than those of the gastric and colon phases. In addition, there was no significant difference in As speciation between colonic residual solids and faeces (p > 0.05). This work provides a better view of human health risk evaluation on rice bran As consumption in humans.

Arsenic concentrations, diversity and co-occurrence patterns of bacterial and fungal communities in the feces of mice under sub-chronic arsenic exposure through food

BACKGROUND

Arsenic, a global pollutant and a threshold-free primary carcinogen, can accumulate in rice. Previous studies have focused on arsenic poisoning in drinking water and the effects on gut microbes. The research on arseniasis through food, which involves the bio-transformation of arsenic, and the related changes in gut microbiome is insufficient.

METHOD

Mice were exposed from animal feed prepared with four arsenic species (iAs^III, iAs^V, MMA, and DMA) at a dose of 30 mg/kg according to the arsenic species proportion in rice for 30 days and 60 days. The levels of total arsenic (tAs) and arsenic species in mice feces and urine samples were determined using ICP-MS and HPLC-ICP-MS, respectively. 16S rRNA and ITS gene sequencing were conducted on microbial DNA extracted from the feces samples.

RESULTS

At 30 days and 60 days exposure, the tAs levels excreted from urine were 0.0092 and 0.0093 mg/day, and tAs levels in feces were 0.0441 and 0.0409 mg/day, respectively. We found significant differences in arsenic species distribution in urine and feces (p < 0.05). In urine, the predominant arsenic species were iAs^III (23% and 14%, respectively), DMA (55% and 70%, respectively), and uAs (unknown arsenic, 14% and 10%, respectively). In feces, the proportion of major arsenic species (iAs^V, 26% and 21%; iAs^III, 16% and 15%; MMA, 14% and 14%; DMA, 19% and 19%; and uAs, 22% and 29%, respectively) were evenly distributed. Microbiological analysis (MRPP test, α- and β-diversities) showed that diversity of gut bacteria was significantly related to arsenic exposure through food, but diversity of gut fungi is less affected. Manhattan plot and LEfSe analysis showed that arsenic exposure significantly changes microbial taxa, which might be directly associated with arsenic metabolism and diseases mediated by arsenic exposure, such as Deltaproteobacteria, Polynucleobacter, Saccharomyces, Candida, Amanitaceae, and Fusarium. Network analysis was used to identify the changing hub taxa in feces along with arsenic exposure. Function predicting analysis indicated that arsenic exposure might also significantly increase differential metabolic pathways and would disturb carbohydrates, lipid, and amino acids metabolism of gut bacteria.

CONCLUSIONS

The results demonstrate that subchronic arsenic exposure via food significantly changes the gut microbiome, and the toxicity of arsenic in food, especially in staples, should be comprehensively evaluated in terms of the disturbance of microbiome, and feces might be the main pathway through which arsenic from food exposure is excreted and bio-transformed, providing a new insight into the investigation of bio-detoxification for arseniasis.