Highly integrated automatic injection terahertz microfluidic biosensor based on metasurface and LT-GaAs photoconductive antenna.

In this paper, a highly integrated terahertz (THz) biosensor is proposed and implemented, which pioneered the preparation of low-temperature gallium arsenide (LT-GaAs) thin film photoconductive antenna (PCA) on the sensor for direct generation and detection of THz waves, simplifying complex terahertz time-domain spectroscopy (THz-TDS) systems. A latch type metasurface is deposited in the detection region to produce a resonance absorption peak at 0.6 THz that is independent of polarisation. Microfluidics is utilised and automatic injection is incorporated to mitigate the experimental effects of hydrogen bond absorption of THz waves in aqueous-based environment. Additionally, cell damage is minimised by regulating the cell flow rate. The biosensor was utilised to detect the concentration of three distinct sizes of bacteria with successful results. The assay was executed as a proof of concept to detect two distinct types of breast cancer cells. Based on the experimental findings, it has been observed that the amplitude and blueshift of the resonance absorption peaks have the ability to identify and differentiate various cancer cell types. The findings of this study introduce a novel approach for developing microfluidic THz metasurface biosensors that possess exceptional levels of integration, sensitivity, and rapid label-free detection capabilities.

Data mining of arsenic-based small molecules geometrics present in Cambridge structural database.

Arsenic, ubiquitous in various industrial processes and consumer products, presents both essential functions and considerable toxicity risks, driving extensive research into safer applications. Our investigation, drawing from 7182 arsenic-containing molecules in the Cambridge Structural Database (CSD), outlines their diverse bonding patterns. Notably, 51% of these molecules exhibit cyclic connections, while 49% display acyclic ones. Arsenic forms eight distinct bonding types with other elements, with significant interactions observed, particularly with phenyl rings, O3 and F6 moieties. Top interactions involve carbon, nitrogen, oxygen, fluorine, sulfur, and arsenic itself. We meticulously evaluated average bond lengths under three conditions: without an R-factor cut-off, with R-factor ≤0.075, and with R-factor ≤0.05, supporting the credibility of our results. Comparative analysis with existing literature data enriches our understanding of arsenic's bonding behaviour. Our findings illuminate the structural attributes, molecular coordination, geometry, and bond lengths of arsenic with 68 diverse atoms, enriching our comprehension of arsenic chemistry. These revelations not only offer a pathway for crafting innovative and safer arsenic-based compounds but also foster the evolution of arsenic detoxification mechanisms, tackling pivotal health and environmental challenges linked to arsenic exposure across different contexts.

[Research hotspots and frontiers of Realgar based on CiteSpace knowledge graph analysis].

This study employed knowledge graph technology to analyze the research status and hot spots of Realgar and provide guidance for clinical application and further research of this drug. The research articles both in English and Chinese involving Realgar were retrieved from five databases including CNKI, Wanfang, VIP, SinoMed, and Web of Science. And NoteExpress, a literature management software was used to screen literature. CiteSpace was utilized for visualized analysis and presentations of the authors, institutions, and keywords. 2 879 articles in Chinese and 194 articles in English were included. China Journal of Chinese Materia Medica and Journal of Ethnopharmacology were the top Chinese and English journals in terms of publication volume. Realgar is widely used in the treatment of skin diseases, blood diseases, and cancer. JIANG Hong was the author who have published more articles in Chinese and English working with teams. School of Public Health of China Medical University and China Academy of Chinese Medical Sciences published the most articles in Chinese and English. The research on Realgar mainly focuses on clinical application, mechanism of action, reduction of toxicity, and enhancement of efficacy. The authors and institutions of Realgar research are mainly concentrated in China. The study on the mechanism of treating hematological diseases and cancer with Realgar, as well as the research on its effects of reducing toxicity and enhancing efficacy, are the current research hotspots. The mechanism of "same treatment for different diseases" in Realgar needs to be further explored. It is urgent to carry out interdisciplinary research on Realgar. This study can provide a refe-rence for the clinical application of Realgar and provide ideas for further research on Realgar.

Novel insights into the kinetics and mechanism of arsenopyrite bio-dissolution enhanced by pyrite.

Arsenopyrite and pyrite often coexist in metal deposits and tailings, thus simultaneous bioleaching of both sulfides has economic (as well as environmental) significance. Important targets in bio-oxidation operations are high solubilization rates and minimized accumulation of Fe(III)/As-bearing secondary products. This study investigated the role of pyrite bioleaching in the enhancement of arsenopyrite dissolution. At a pyrite to arsenopyrite mass ratio of 1:1, 93.6% of As and 93.0% of Fe were solubilized. The results show that pyrite bio-oxidation can promote arsenopyrite dissolution, enhance S0 bio-oxidation, and inhibit the formation of jarosites, tooeleite, and amorphous ferric arsenate. The dry weight of the pyrite & arsenopyrite residue was reduced by 95.1% after bioleaching, compared to the initial load, while only 5% weight loss was observed when pyrite was absent. A biofilm was formed on the arsenopyrite surface in the presence of pyrite, while a dense passivation layer was observed in the absence of pyrite. As(III) (as As2O3) was a dominant As species in the pyrite & arsenopyrite residue. Novel and detailed findings are presented on arsenopyrite bio-dissolution in the presence of pyrite, and the presented approach could contribute to the development of novel cost-effective extractive bioprocesses. ENVIRONMENTAL IMPLICATION: The oxidation of arsenopyrite presents significant environmental hazards, as it can contribute to acid mine drainage generation and arsenic mobilization from sulfidic mine wastes. Bioleaching is a proven cost-effective and environmentally friendly extractive technology, which has been applied for decades in metal recovery from minerals or tailings. In this work, efficient extraction of arsenic from arsenopyrite bioleaching was presented through coupling the process with bio-oxidation of pyrite, resulting in lowered accumulation of hazardous and metastable Fe(III)/As-bearing secondary phases. The results could help improve current biomining operations and/or contribute to the development of novel cost-effective bioprocesses for metal extraction.

Lipophilic arsenic compounds in the cultured green alga Chlamydomonas reinhardtii.

In this study, arsenic (As) speciation was investigated in the freshwater alga Chlamydomonas reinhardtii treated with 20 µg/L arsenate using fractionation as well as ICP-MS/ESI-MS analyses and was compared with the known As metabolite profile of wild-grown Saccharina latissima. While the total As accumulation in C. reinhardtii was about 85% lower than in S. latissima, the relative percentage of arsenolipids was significantly higher in C. reinhardtii (57.0% vs. 5.01%). As-containing hydrocarbons and phospholipids dominated the hydrophobic As profile in S. latissima, but no As-containing hydrocarbons were detectable in C. reinhardtii. Instead for the first time, an arsenoriboside-containing phytol (AsSugPhytol) was found to dominate the hydrophobic arsenicals of C. reinhardtii. Interestingly, this compound and its relatives had so far been only found in green marine microalgae, open sea plankton (mixed assemblage), and sediments but not in brown or red macroalgae. This compound family might therefore relate to differences in the arsenic metabolism between the algae phyla.

Recent progress in analytical strategies of arsenic-binding proteomes in living systems.

Arsenic (As) is one of the most concerning elements due to its high exposure risks to organisms and ecosystems. The interaction between arsenicals and proteins plays a pivotal role in inducing their biological effects on living systems, e.g., arsenicosis. In this review article, the recent advances in analytical techniques and methods of As-binding proteomes were well summarized and discussed, including chromatographic separation and purification, biotin-streptavidin pull-down probes, in situ imaging using novel fluorescent probes, and protein identification. These analytical technologies could provide a growing body of knowledge regarding the composition, level, and distribution of As-binding proteomes in both cells and biological samples, even at the organellar level. The perspectives on analysis of As-binding proteomes are also proposed, e.g., isolation and identification of minor proteins, in vivo targeted protein degradation (TPD) technologies, and spatial As-binding proteomics. The application and development of sensitive, accurate, and high-throughput methodologies of As-binding proteomics would enable us to address the key molecular mechanisms underlying the adverse health effects of arsenicals.

Detection of Be dopant pairing in VLS grown GaAs nanowires with twinning superlattices.

Control over the distribution of dopants in nanowires is essential for regulating their electronic properties, but perturbations in nanowire microstructure may affect doping. Conversely, dopants may be used to control nanowire microstructure including the generation of twinning superlattices (TSLs)-periodic arrays of twin planes. Here the spatial distribution of Be dopants in a GaAs nanowire with a TSL is investigated using atom probe tomography. Homogeneous dopant distributions in both the radial and axial directions are observed, indicating a decoupling of the dopant distribution from the nanowire microstructure. Although the dopant distribution is microscopically homogenous, radial distribution function analysis discovered that 1% of the Be atoms occur in substitutional-interstitial pairs. The pairing confirms theoretical predictions based on the low defect formation energy. These findings indicate that using dopants to engineer microstructure does not necessarily imply that the dopant distribution is non-uniform.

Identification of Monomethylmonothioarsonic Acid as the Major Thioarsenical Generated During Extraction Processes for Arsenic Species Analysis.

Acid extraction is commonly used to analyze arsenic species in rice. During the extraction process, spiked monomethylarsonic acid (MMA) is often transformed into different compounds. A similar phenomenon is observed in the arsenic speciation analysis of seafood. To identify these compounds, we analyzed a previously prepared extract using liquid chromatography-time-of-flight/mass spectrometry in differential analysis and liquid chromatography-inductively coupled plasma-MS. The compound was identified as monomethylmonothioarsonic acid (MMMTA), a thioarsenical, which is estimated to be more cytotoxic than MMA. As MMMTA was readily produced by bubbling hydrogen sulfide through MMA, this suggests that MMA reacts with sulfur in rice during the extraction process. Our data also suggested that dimethylarsinic acid could be transformed into another compound, although the generation rate was low. For reliable arsenic speciation analyses, the transformation of arsenic compounds during extraction must be avoided. This study demonstrates that arsenic compounds can be transformed by dilute acid extraction.

Fate of 14 C-MSMA in a soil column study simulating herbicide use environments.

Monosodium methanearsonate (MSMA), a selective contact herbicide, is a sodium salt of monomethyl arsenic acid (MMA or MAA). This paper focuses on the environmental fate of MMA. Decades of research have shown that a significant portion of applied MSMA drips to soil and is sorbed quickly. The fraction available for leaching or biological uptake decreases at a biphasic rate, first rapidly and then at a slower rate. A soil column study was designed to obtain quantitative information about MMA sorption and transformation and the effects of different environmental variables on these processes, in conditions simulating the environment of MSMA use on cotton and turf. Using 14 C-MSMA, this study quantified MSMA-derived arsenic species and differentiated between added arsenic and soil background levels. Similar behavior of MSMA was observed across all test systems with respect to sorption, transformation, and mobility, despite differences in soil type and rainfall treatment. All soil columns exhibited a rapid sorption of added MMA followed by continual sorption of residues into the soil matrix. Within the first 2 days, only 20%-25% of radioactivity was extracted by water. On day 90, less than 3.1% of added MMA was in a water extractable phase. MMA sorption was most rapid in the soil with the higher clay content. Dominant extractable arsenic species were MMA, dimethylarsinic acid, and arsenate, indicating that methylation and demethylation occurred. In all MSMA-treated columns, arsenite concentrations were negligible and indiscernible from those in untreated columns.

Effect of surface gallium termination on the formation and emission energy of an InGaAs wetting layer during the growth of InGaAs quantum dots by droplet epitaxy.

Self-assembled quantum dots (QDs) based on III-V semiconductors have excellent properties for applications in quantum optics. However, the presence of a 2D wetting layer (WL) which forms during the Stranski-Krastanov growth of QDs can limit their performance. Here, we investigate WL formation during QD growth by the droplet epitaxy technique. We use a combination of photoluminescence excitation spectroscopy, lifetime measurements, and transmission electron microscopy to identify the presence of an InGaAs WL in these droplet epitaxy QDs, even in the absence of distinguishable WL luminescence. We observe that increasing the amount of Ga deposited on a GaAs (100) surface prior to the growth of InGaAs QDs leads to a significant reduction in the emission wavelength of the WL to the point where it can no longer be distinguished from the GaAs acceptor peak emission in photoluminescence measurements. However increasing the amount of Ga deposited does not suppress the formation of a WL under the growth conditions used here.

Arsenic trioxide and Erlotinib loaded in RGD-modified nanoliposomes for targeted combination delivery to PC3 and PANC-1 cell lines.

During the past few years, advances in drag delivery have provided many opportunities in the treatment of various diseases and cancer. Arsenic trioxide (ATO) and Erlotinib (Erlo) are two drugs, approved by the United States Food and Drug Administration to treat cancer, but their use is limited in terms of the toxicity of ATO and the low solubility of Erlo. This study aimed to prepare arginine-glycine-aspartic acid (RGD)-decorated nanoliposomes (NLPs) containing Erlo and ATO (NLPs-ATO-Erlo-RGD) to increase the solubility and reduce the toxicity of Erlo and ATO for cancer treatment. The results of transmission electron microscopy and dynamic light scattering showed that NLPs were synthesized uniformly, with spherical shape morphology and particle sizes between 140 and 160 nm. High-performance liquid chromatography and ICP-MS results showed that about 90% of the drug was loaded in the NLPs. In comparison with NLPs-ATO-Erlo, NLPs-ATO-Erlo-RGD demonstrated considerable toxicity against the αvß3 overexpressing PC3 cell line in the MTT experiment. It had no effect on the PANC-1 cell line. In addition, apoptosis assays using Annexin V/PI demonstrated that NLPs-ATO-Erlo-RGD generated the highest apoptotic rates in PC3 cells when compared with NLPs-ATO-Erlo and the combination of free ATO and Erlo. Furthermore, treatment with NLPs-ATO-Erlo-RGD in (p < 0.05) PC3 cell line significantly reduced EGFR level. It is concluded NLPs-ATO-Erlo-RGD as a novel drug delivery system may be a promising platform for the treatment of cancer.

Photochemical approach for multiplexed biofunctionalisation of gallium arsenide.

The optoelectronic properties of gallium arsenide (GaAs) hold great promise in biosensing applications, currently being held back by the lack of methodologies reporting the spatially selective functionalisation of this material with multiple biomolecules. Here, we exploit the use of a photoreactive crosslinker - a diazirine derivative - for spatially selective covalent immobilisation of multiple bioreceptors on the GaAs surface. As a proof of principle we show the immobilisation of two proteins: neutravidin and endosulfine alpha protein. X-ray photoelectron spectroscopy results showed the presence of the biomolecules on the GaAs regions selectively exposed to ultraviolet light. The approach presented here is applicable to the covalent attachment of other biomolecules, paving the way for using GaAs as a platform for multiplexed biosensing.

Electronic Transport Properties in GaAs/AlGaAs and InSe/InP Finite Superlattices under the Effect of a Non-Resonant Intense Laser Field and Considering Geometric Modifications.

In this work, a finite periodic superlattice is studied, analyzing the probability of electronic transmission for two types of semiconductor heterostructures, GaAs/AlGaAs and InSe/InP. The changes in the maxima of the quasistationary states for both materials are discussed, making variations in the number of periods of the superlattice and its shape by means of geometric parameters. The effect of a non-resonant intense laser field has been included in the system to analyze the changes in the electronic transport properties by means of the Landauer formalism. It is found that the highest tunneling current is given for the GaAs-based compared to the InSe-based system and that the intense laser field improves the current-voltage characteristics generating higher current peaks, maintaining a negative differential resistance (NDR) effect, both with and without laser field for both materials and this fact allows to tune the magnitude of the current peak with the external field and therefore extend the range of operation for multiple applications. Finally, the power of the system is discussed for different bias voltages as a function of the chemical potential.

Gut microbiota metabolize arsenolipids in a donor dependent way.

Understanding the interplay between the gut microbiome and arsenolipids can help us manage the potential health risk of consuming seafood, but little is known about the bioconversion fate of arsenolipids in the gastrointestinal tract. We use an in vitro mucosal simulator of the human intestinal microbial ecosystem (M-SHIME) to mimic the digestive tract of four healthy donors during exposure to two arsenolipids (an arsenic fatty acid AsFA 362 or an arsenic hydrocarbon AsHC 332). The metabolites were analyzed by HPLC-mass spectrometry. The human gut bacteria accumulated arsenolipids in a donor-dependent way, with higher retention of AsHC 332. Colonic microbiota partly transformed both arsenolipids to their thioxo analogs, while AsFA 362 was additionally transformed into arsenic-containing fatty esters, arsenic-containing fatty alcohols, and arsenic-containing sterols. There was no significant difference in water-soluble arsenicals between arsenolipid treatments. The study shows that arsenolipids can be quickly biotransformed into several lipid-soluble arsenicals of unknown toxicity, which cannot be excluded when considering potential implications on human health.

The ArsI C-As lyase: Elucidating the catalytic mechanism of degradation of organoarsenicals.

Organoarsenicals such as monosodium methylarsenate (MSMA or MAs(V)) and roxarsone (4-hydroxyl-3-nitrophenylarsenate or Rox(V)) have been extensively used as herbicides and growth enhancers for poultry, respectively. Degradation of organoarsenicals to inorganic arsenite (As(III)) contaminates crops and drinking water. One such process is catalyzed by the bacterial enzyme ArsI, whose gene is found in many soil bacteria. ArsI is a non-heme ferrous iron (Fe(II))-dependent dioxygenase that catalyzes oxygen-dependent cleavage of the carbon­arsenic (C-As) bond in trivalent organoarsenicals, degrading them to inorganic As(III). From previous crystal structures of ArsI, we predicted that a loop-gating mechanism controls the catalytic reaction. Understanding the catalytic mechanism of ArsI requires knowledge of the mechanisms of substrate binding and activation of dioxygen. Here we report new ArsI structures with bound Rox(III) and mutant enzymes with alteration of active site residues. Our results elucidate steps in the catalytic cycle of this novel dioxygenase and enhance understanding of the recycling of environmental organoarsenicals.

Phenylarsonic acid-DMPS redox reaction and conjugation investigated by NMR spectroscopy and X-ray diffraction.

The reaction between 2,3-dimercaptopropane-1-sulfonate (DMPS, unithiol) and four phenylarsonic(V) acids, i.e. phenylarsonic acid (PAA), 4-hydroxy-3-nitrophenylarsonic acid (HNPAA), 2-aminophenylarsonic acid (o-APAA) and 4-aminophenylarsonic acid (p-APAA), is investigated in aqueous solution. The pentavalent arsenic compounds are reduced by DMPS to their trivalent analogs and instantly chelated by the vicinal dithiol, forming covalent As-S bonds within a five-membered chelate ring. The different types and positions of polar substituents at the aromatic ring of the arsonic acids influence the reaction rates in the same way as observed for reaction with glutathione (GSH), as well as the syn/anti molar ratio of the diastereomeric products, which was analyzed using time- and temperature-dependent nuclear magnetic resonance (NMR) spectroscopy. Addition of DMPS to the conjugate formed by a phenylarsonic(V) acid and the biologically relevant tripeptide GSH showed the immediate replacement of GSH by chelating DMPS, underlining the importance of dithiols as detoxifying agent.

A pathway of the generation of acid mine drainage and release of arsenic in the bioleaching of orpiment.

Arsenic in acid mine drainage (AMD) is commonly associated with the bioleaching of arsenic sulfide minerals. Orpiment is iron free and one of the most common arsenic sulfide minerals, but no studies are involved with the relationship between the iron free bioleaching of orpiment and the generation of arsenic-containing AMD. In this study, the iron free bioleaching experiments with Acidithiobacillus thiooxidans (T.t) or Acidithiobacillus caldus (A.c) were carried out. In the experiments with T.t, the pH value decreased with time, and the leached arsenic increased significantly. Meanwhile, the density of planktonic bacteria increased gradually, suggesting that T.t survived in the orpiment pulp. However, in the experiments with initial pH of 1, pH changed little and arsenic was nearly not leached, implying that the bioleaching of orpiment can be inhibited when the initial pH was too low. The XRD patterns and the TFESEM-EDS analyses showed that no elemental sulfur was detected on the orpiment surface. It was supposed that the sulfur was converted to sulfuric acid in the bioleaching process. The CFESEM images showed that no corrosion pits were formed though a few cells adhered to the orpiment surface, and the TEM images showed that no extracellular polymeric substances (EPS) were excreted by the attached cells on the orpiment particles. In the experiments with A.c, similar results were obtained. It is inferred that the bioleaching of orpiment under iron deficient conditions in mining areas generates arsenic-containing AMD, but can be inhibited when the initial pH is too low.

Widespread Occurrence of the Highly Toxic Dimethylated Monothioarsenate (DMMTA) in Rice Globally.

Arsenic (As) accumulation in rice is of global concern for human health and international trade. Rice is typically reported to contain inorganic As (iAs) and dimethylated arsenate (DMA), with current food guidelines limiting toxic iAs but not less-toxic DMA. Here, we show that the highly toxic dimethylated monothioarsenate (DMMTA) is also found in rice worldwide and has been unknowingly determined as less-toxic DMA by previous routine analytical methods. Using enzymatic extraction followed by high-performance liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS) analysis with a C18 column, DMMTA was detected in rice grains (n = 103) from a field survey from China and in polished rice grains (n = 140) from a global market-basket survey. Concentration ranged from <0.20 to 34.8 µg/kg (median 10.3 µg/kg), accounting for 0 to 21% of total As. A strong linear correlation was observed in all rice samples between DMA and DMMTA (being 30 ± 8% of DMA) concentrations. This robust relationship allows an estimation of DMMTA in rice grains from the DMA data reported in previous market-basket surveys, showing a general global geographical pattern with DMMTA concentration increasing from the equator toward high-latitude regions. Based on the global occurrence and potential high toxicity, DMMTA in rice should be considered in health risk assessments and for setting food regulations.

Inorganic arsenic speciation analysis in food using HPLC/ICP-MS: Method development and validation.

Arsenic (As) compounds can be classified as organic or inorganic, with inorganic arsenic (iAs) having significantly higher toxicity than organic As. As may accumulate in food materials that have been exposed to As-contaminated environments. Thus, the "Sanitation Standard for Contaminants and Toxins in Foods" published by the Ministry of Health and Welfare set the standard limits for iAs content in rice, seaweed, seafood, and marine oils to safeguard public health. Therefore, a robust analytical method must be developed to selectively and quantitatively determine iAs content in rice, seaweed, seafood, and marine oils. Herein, we reported and verified the method of combined high-performance liquid chromatography/inductively coupled plasma-mass spectrometry (HPLC/ICP-MS) to determine iAs content in a wide variety of food. The fish oil samples were spiked with different concentrations of the As(III) standard solution, and their iAs analyzes were obtained via extraction procedures using the 1% (w/w) nitric acid (HNO3) solution containing 0.2 M hydrogen peroxide (H2O2) under sonication. The extracts were subsequently analyzed for their As(V) contents using HPLC/ICP-MS with aqueous ammonium carbonate as the mobile phase. The As(III) species had completely oxidized into the As(V) species, which prevented interferences between organic and iAs during chromatography. The method showed good extraction efficiencies (generally >90%) for the iAs samples, and their limits of quantification in fish oil were 0.02 mg/kg. The method was verified via the iAs speciation analytes of rice, seaweed, seafood, and marine oil matrices. The average recoveries for the fortified samples of each matrix ranged from 87.5 to 112.4%, with their coefficients of variation being less than 10%. Surveillance studies were conducted on the iAs contents of food samples purchased from local Taiwanese markets. The results showed that the only Hijiki (Sargassum fusiforme) higher than the maximum limit of the sanitation standard for iAs in seaweed, whereas the remaining samples met their corresponding requirements. This method is quick and straightforward, and it can be applied for the routine analysis of iAs content in a wide variety of food products to ensure public health safety.

Toxic blister agents: Chemistry, mode of their action and effective treatment strategies.

Since their use during the First World War, Blister agents have posed a major threat to the individuals and have caused around two million casualties. Major incidents occurred not only due to their use as chemical warfare agents but also because of occupational hazards. Therefore, a clear understanding of these agents and their mode of action is essential to develop effective decontamination and therapeutic strategies. The blister agents have been categorised on the basis of their chemistry and the biological interactions that entail post contamination. These compounds have been known to majorly cause blisters/bullae along with alkylation of the contaminated DNA. However, due to the high toxicity and restricted use, very little research has been conducted and a lot remains to be clearly understood about these compounds. Various decontamination solutions and detection technologies have been developed, which have proven to be effective for their timely mitigation. But a major hurdle seems to be the lack of proper understanding of the toxicological mechanism of action of these compounds. Current review is about the detailed and updated information on physical, chemical and biological aspects of various blister agents. It also illustrates the mechanism of their action, toxicological effects, detection technologies and possible decontamination strategies.