Synergistic activation of lamellar bismuth selenide anchored functionalized carbon nanofiber for detecting hazardous carbendazim in environmental water samples

Pesticides pollute natural water reservoirs through persistent accumulation. Therefore, their toxicity and degradability are serious issues. Carbendazim (CBZ) is a pesticide used against fungal infections in agricultural crops, and its overexploitation detrimentally affects aquatic ecosystems and organisms. It is necessary to design a logical, efficient, and field-deployable method for monitoring the amount of CBZ in environmental samples. Herein, a nano-engineered bismuth selenide (Bi2Se3)/functionalized carbon nanofiber (f-CNF) nanocomposite was utilized as an electrocatalyst to fabricate an electrochemical sensing platform for CBZ. Bi2Se3/f-CNF exhibited a substantial electroactive surface area, high electrocatalytic activity, and high conductivity owing to the synergistic interaction of Bi2Se3 with f-CNF. The structural chemical compositions and morphology of the Bi2Se3/f-CNF nanocomposite were confirmed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and field-emission scanning electron microscopy (FESEM). Electrochemical analysis was carried out using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV). The voltammetry and impedance experiments exposed that the Bi2Se3/f-CNF-modified GCE has attained adequate electrocatalytic function with amended features of electron transportation (Rct = 35.93 Ω) and improved reaction sites (0.082 cm2) accessible by CBZ moiety along with exemplary electrochemical stability (98.92%). The Bi2Se3/f-CNF nanocomposite exhibited higher sensitivity of 0.2974 μA μM-1cm-2 and a remarkably low limit of detection (LOD) of 1.04 nM at a broad linera range 0.001-100 μM. The practicability of the nanocomposite was tested in environmental (tap and pond water) samples, which supports excellent signal amplification with satisfactory recoveries. Hence, the Bi2Se3/f-CNF nanocomposite is a promising electrode modifier for detecting CBZ.

Rapid and sensitive detection of Salmonella in agro-Food and environmental samples: A review of advances in rapid tests and biosensors

Salmonella is as an intracellular bacterium, causing many human fatalities when the host-specific serotypes reach the host gastrointestinal tract. Nontyphoidal Salmonella are responsible for numerous foodborne outbreaks and product recalls worldwide whereas typhoidal Salmonella are responsible for Typhoid fever cases in developing countries. Yet, Salmonella-related foodborne disease outbreaks through its food and water contaminations have urged the advancement of rapid and sensitive Salmonella-detecting methods for public health protection. While conventional detection methods are time-consuming and ineffective for monitoring foodstuffs with short shelf lives, advances in microbiology, molecular biology and biosensor methods have hastened the detection. Here, the review discusses Salmonella pathogenic mechanisms and its detection technology advancements (fundamental concepts, features, implementations, efficiency, benefits, limitations and prospects). The time-efficiency of each rapid test method is discussed in relation to their limit of detections (LODs) and time required from sample enrichment to final data analysis. Importantly, the matrix effects (LODs and sample enrichments) were compared within the methods to potentially speculate Salmonella detection from environmental, clinical or food matrices using certain techniques. Although biotechnological advancements have led to various time-efficient Salmonella-detecting techniques, one should consider the usage of sophisticated equipment to run the analysis by moderately to highly trained personnel. Ultimately, a fast, accurate Salmonella screening that is readily executed by untrained personnels from various matrices, is desired for public health procurement.

A comprehensive survey of reference materials for their use in quality assurance for the determination of Np-237 in environmental samples

Neptunium-237 (237Np) is one of the most hazardous radionuclides of public concern due to its radiological toxicity, long half-life and high environmental mobility. Standard reference materials (SRMs) with well characterized 237Np activity concentrations are valuable for method development and validation of 237Np determination in environmental samples. In this study, a comprehensive literature survey of 237Np activity concentrations in 25 SRMs was carried out covering the various matrices of sediment, soil, seawater, atmospheric particles, and biota. After data screening, arithmetic mean of the activity concentrations of 237Np in literatures were calculated as statistical values (SVs). Then, accuracies of different instrument analyses and acid digestion methods were evaluated based on the SVs. Finally, by optimizing the sector field ICP-MS analytical method, 237Np activity concentration in JSAC-0471 soil SRM was measured. The application of SVs provides 237Np activity concentration information in more SRMs. Besides SRMs certified by technically validated procedures, SRMs with SVs and the measurement of JASC-0471 provide more options for suitable selection of SRMs for 237Np determination.

Development of Simple Fluorescence Analytical Strategy for the Detection of Triazophos Using Greenish-Yellow Emissive Carbon Dots Derived from Curcuma longa

This study describes a new method for synthesizing water-soluble carbon dots (CDs) using "Curcuma longa" (green source) named CL-CDs via a single-step hydrothermal process. The as-synthesized CL-CDs exhibited greenish-yellow fluorescence at 548 nm upon excitation at 440 nm. It shows good water stability and exhibits a quantum yield of 19.4%. The developed probe is utilized for sensing triazophos (TZP) pesticide via a dynamic quenching mechanism, exhibiting favorable linearity ranging from 0.5-500 μM with a limit of detection of 0.0042 μM. The as-prepared CL-CDs probe was sensitive and selective towards TZP. Lastly, the successful application of the CL-CDs-based fluorescent probe in water and rice samples highlights its potential as a reliable and efficient method for the detection of TZP in various real sample matrices. Eventually, bioimaging and biocompatibility aspects of CL-CDs have been assessed on Saccharomyces cerevisiae (yeast) cell and lung cancer (A549) cell lines, respectively.

Using optimized particle imaging of micro-Raman to characterize microplastics in water samples

Characterizing the chemical properties, morphologies, size, and quantities of microplastics (MPs) in water samples with high precision is critically important for understanding the environmental behaviors of MPs. Traditional detection methods, such as Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy point-by-point detection, provide worthy reference techniques but are time- and labor-consuming. We established a super time-saving and high-precision technique to characterize MPs using micro-Raman automatic particle identification (MR-API). Based on the identification of PS spheres, screen magnification, exposure time, and the number of scans are selected as crucial detection parameters for MR-API analysis, which highly affect the precision of the results. Detecting particles down to 1 μm requires magnification of the mosaic until the scale showed 200 μm. The recommended setting parameters were 83.33 or 100 ms exposure time, 20 scans, 7 mW laser power, and 1 μm image pixel size, suitable for polystyrene (PS), polypropylene (PP), polyethylene terephthalate (PET), polyethylene (PE), polyvinyl chloride (PVC), and polyamide (PA) particles detection. With the complete procedure of MR-API measurements, the recovery of MPs was 61.67-90.00 %. To validate the feasibility of the MR-API, the method was used to detect samples of known plastic types (mask leachates) and unknown plastic types (urban lake). A total of 4540 particles in the sample of mask leachates consuming 35 h 50 min 43 s, and 0.92 ± 0.49 % of particles were identified as MPs. The urban river sample efficiently identified PP, PET, PE, PVC, PS, EVA, and VC/VAC MPs using this method. The detected MPs size ranged from 8.3 to 5000 μm, saving 75.03 % and 58.38 % of the time compared to the conventional micro-FTIR and micro-Raman point-by-point methods, respectively. Therefore, this method is effective for detecting MPs in the environmental samples and has excellent prospects.

Development of reference material for quality control of uranium analysis in marine sediments

Environmental radioactivity monitoring is strengthening due to public concerns over radioactive contamination since the Fukushima nuclear power plant accident. Therefore, various research laboratories, institutes, and universities have been conducting environmental radioactivity surveys around nuclear power plants (NPPs). However, the reliability of the results continues to trigger controversy in society. This study was conducted to develop reference material (RM) for the quality control of 238U and 234U analyses in marine sediments. The RM was prepared according to ISO Guides 31, 34, and 35. A homogeneity test of the marine sediment RM was implemented by analyzing two batch samples from ten bottles using multiple acid digestion and alkali fusion, respectively. We found that the 238U and 234U reference values of the RM were 43.0 ± 1.7 Bq kg-1(k=1) and 41.5 ± 1.9 Bq kg-1(k=1), respectively. This marine sediment RM will be useful for the quality control of analytical methods for similar samples and proficiency tests.

Environmental DNA metabarcoding serves as a promising method for aquatic species monitoring and management: A review focused on its workflow, applications, challenges and prospects

Marine and freshwater biodiversity is under threat from both natural and manmade causes. Biological monitoring is currently a top priority for biodiversity protection. Given present limitations, traditional biological monitoring methods may not achieve the proposed monitoring aims. Environmental DNA metabarcoding technology reflects species information by capturing and extracting DNA from environmental samples, using molecular biology techniques to sequence and analyze the DNA, and comparing the obtained information with existing reference libraries to obtain species identification. However, its practical application has highlighted several limitations. This paper summarizes the main steps in the environmental application of eDNA metabarcoding technology in aquatic ecosystems, including the discovery of unknown species, the detection of invasive species, and evaluations of biodiversity. At present, with the rapid development of big data and artificial intelligence, certain advanced technologies and devices can be combined with environmental DNA metabarcoding technology to promote further development of aquatic species monitoring and management.

Targeted volume correlative light and electron microscopy of an environmental marine microorganism

Photosynthetic microalgae are responsible for an important fraction of CO2 fixation and O2 production on Earth. Three-dimensional (3D) ultrastructural characterization of these organisms in their natural environment can contribute to a deeper understanding of their cell biology. However, the low throughput of volume electron microscopy (vEM) methods along with the complexity and heterogeneity of environmental samples pose great technical challenges. In the present study, we used a workflow based on a specific electron microscopy sample preparation method compatible with both light and vEM imaging in order to target one cell among a complex natural community. This method revealed the 3D subcellular landscape of a photosynthetic dinoflagellate, which we identified as Ensiculifera tyrrhenica, with quantitative characterization of multiple organelles. We show that this cell contains a single convoluted chloroplast and show the arrangement of the flagellar apparatus with its associated photosensitive elements. Moreover, we observed partial chromatin unfolding, potentially associated with transcription activity in these organisms, in which chromosomes are permanently condensed. Together with providing insights in dinoflagellate biology, this proof-of-principle study illustrates an efficient tool for the targeted ultrastructural analysis of environmental microorganisms in heterogeneous mixes.

Multiple heteroatom dopant carbon dots as a novel photoluminescent probe for the sensitive detection of Cu2+ and Fe3+ ions in living cells and environmental sample analysis

Heavy metal ion pollution harms human health and the environment and continues to worsen. Here, we report the synthesis of boron (B), phosphorous (P), nitrogen (N), and sulfur (S) co-doped carbon dots (BP/NS-CDs) by a one-step facile hydrothermal process. The optimum synthetic parameters are of 180 °C temperature, 12 h reaction time and 15% of PBA mass. The as-synthesized BP/NS-CDs exhibits excellent water solubility, strong green photoluminescence (PL) at 510 nm, and a high quantum yield of 22.4%. Moreover, BP/NS-CDs presented high monodispersity (7.2 ± 0.45 nm), excitation-dependent emission, PL stability over large pH, and high ionic strength. FTIR, XRD, and XPS are used to confirm the successful B and P doping of BP/NS-CDs. BP/NS-CD photoluminescent probes are selectively quenched by Cu²⁺ and Fe³⁺ ions but showed no response to the presence of other metal cations. The PL emission of BP/NS-CDs exhibited a good linear correlation with Cu²⁺ and Fe³⁺ concentrations with detection limits of 0.18 μM and 0.27 μM for Cu²⁺ and Fe³⁺, respectively. Furthermore, the HCT116 survival cells kept at 99.4 ± 1.3% and cell imaging capability, when the BP/NS-CDs concentration is up to 300 μg/mL by MTT assay. The proposed sensor is potential applications for the detection of Cu²⁺ and Fe³⁺ ions in environmental water samples.

Nitrogen, sulfur, and phosphorus Co-doped carbon dots-based ratiometric chemosensor for highly selective sequential detection of Al3+ and Fe3+ ions in logic gate, cell imaging, and real sample analysis

Heteroatom-doped photoluminescent (PL) carbon dots (CDs) have recently gained attention as optical sensors due to their excellent tunable properties. In this work, we propose a one-pot hydrothermal synthesis of PL nitrogen (N), sulfur (S), and phosphorus (P) co-doped carbon dots (NSP-CDs) using glutathione and phosphoric acid (H₃PO₄) as precursors. The synthesized NSP-CDs were characterized using different spectroscopic and microscopic techniques, including ultraviolet-visible (UV-Vis) spectroscopy, fluorescence spectroscopy, Fourier-transform infrared (FTIR), X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) analysis. The NSP-CDs exhibited excellent PL properties with green emission at 492 nm upon excitation at 417 nm, a high quantum yield of 26.7%, and dependent emission behavior. The as-prepared NSP-CDs were spherical with a well-monodispersed average particle size of 5.2 nm. Moreover, NSP-CDs demonstrate high PL stability toward a wider pH, high salt ionic strength, and various solvents. Furthermore, the NSP-CDs showed a three-state "off-on-off" PL response upon the sequential addition of Al³⁺ and Fe³⁺ ions, with a low limit of detection (LOD) of 10.8 nM for Al³⁺ and 50.7 nM for Fe³⁺. The NSP-CD sensor can construct an INHIBIT logic gate with Al³⁺ and Fe³⁺ ions as the chemical inputs and emissions as the output mode. Owing to an excellent tunable PL property and biocompatibility, the NSP-CDs were applied for sensing Al³⁺ and Fe³⁺ ions as well as live cell imaging. Furthermore, NSP-CDs were designed as PL sensors for detecting Al³⁺ and Fe³⁺ ions in real water show their potential application.

Digital Droplet PCR to Track SARS-CoV-2 Outbreak in a Hospital Transitional Care Unit

We describe an outbreak of SARS-CoV-2 on a transition unit composed of elderly patients awaiting placement. Environmental and patient sample analyses using digital droplet PCR (ddPCR) suggested possible fomite transmission and a high viral burden source from a few individual patients. This outbreak illustrates challenges inherent to this specific patient population.

Sensitive determination of illicit drugs in wastewater using enrichment bag-based liquid-phase microextraction and liquid-chromatography tandem mass spectrometry

To concentrate trace level of analytes in complex wastewater, sample preparation is necessary prior to instrumental analysis. In this work, an enrichment bag-based liquid-phase microextraction (EB-LPME) system was therefore proposed for the first time to isolate and enrich the illicit drugs (amphetamine, methamphetamine, 3,4-methylenedioxymethamphetamine (MDMA), ketamine, codeine and fentanyl) from wastewater. Under the optimum EB-LPME conditions, the recoveries of the model illicit drugs were 40-93% with enrichment factors up to 93. The optimized EB-LPME was compared to hollow fiber-LPME (HF-LPME) in terms of the thickness of the supported liquid membrane (SLM), the effective SLM area, extraction recovery and mass transfer flux. Compared with HF-LPME, EB-LPME possesses larger effective SLM area, and provided higher extraction recovery. In addition, EB-LPME provided larger mass transfer flux than HF-LPME, which was mainly due to the differences in SLM thickness. Therefore, SLM thickness was identified as the main mass transfer flux-determining factor experimentally. The matrix effect of EB-LPME was evaluated using liquid chromatography-tandem mass spectrometry (LC-MS/MS), and excellent sample clean-up was confirmed. Subsequently, EB-LPME-LC-MS/MS was validated with satisfactory results, and the detection of limit of the proposed method was in the range of 0.3-8.7 ng/L. Finally, with standard addition method, EB-LPME-LC-MS/MS was successfully applied for the determination of the model drugs in a local hospital wastewater from Wuhan, China. This study clearly showed that EB-LPME displayed great potential as an efficient sample preparation method for isolation and enrichment of the drugs/pollutants from complex environmental samples for wastewater-based epidemiology in the near future.

PhyloPrimer: a taxon-specific oligonucleotide design platform

Many environmental and biomedical biomonitoring and detection studies aim to explore the presence of specific organisms or gene functionalities in microbiome samples. In such cases, when the study hypotheses can be answered with the exploration of a small number of genes, a targeted PCR-approach is appropriate. However, due to the complexity of environmental microbial communities, the design of specific primers is challenging and can lead to non-specific results. We designed PhyloPrimer, the first user-friendly platform to semi-automate the design of taxon-specific oligos (i.e., PCR primers) for a gene of interest. The main strength of PhyloPrimer is the ability to retrieve and align GenBank gene sequences matching the user’s input, and to explore their relationships through an online dynamic tree. PhyloPrimer then designs oligos specific to the gene sequences selected from the tree and uses the tree non-selected sequences to look for and maximize oligo differences between targeted and non-targeted sequences, therefore increasing oligo taxon-specificity (positive/negative consensus approach). Designed oligos are then checked for the presence of secondary structure with the nearest-neighbor (NN) calculation and the presence of off-target matches with in silico PCR tests, also processing oligos with degenerate bases. Whilst the main function of PhyloPrimer is the design of taxon-specific oligos (down to the species level), the software can also be used for designing oligos to target a gene without any taxonomic specificity, for designing oligos from preselected sequences and for checking predesigned oligos. We validated the pipeline on four commercially available microbial mock communities using PhyloPrimer to design genus- and species-specific primers for the detection of Streptococcus species in the mock communities. The software performed well on these mock microbial communities and can be found at https://www.cerealsdb.uk.net/cerealgenomics/phyloprimer.

Strontium tungstate-modified disposable strip for electrochemical detection of sulfadiazine in environmental samples

Rapid-monitoring of drugs has attracted tremendous consideration owing to robust global demand for cost-effective and high effectiveness. Binary metal oxides with various morphology have been reported as electrodes for electrochemical sensor to fulfilling the clinical and enviromental requirements. In this study, strontium tungstate (SrWO₄) nanoflakes have been successfully prepared via the facile sonochemical method for the first time. The characteristics of as-prepared SrWO₄ are systematically measured by various analytical and spectroscopic methods. The SrWO₄ nanoflakes are utilized to modify the electrochemical electrode for the sulfadiazine (SDZ) determination. The SrWO₄ modified electrode possesses excellent electrocatalytic activity and high recognition capability for the electrochemical detection of SDZ. Impressively, the as-fabricated SrWO₄ modified electrode attainted lowest oxidation peak at +0.93 V (vs Ag/AgCl₂) with the limit of detection of 0.009 μM, the sensitivity of 0.123 µA µM^-1 cm² and linear detection range of 0.05-235 μM. The enhanced performance of proposed SrWO₄-based sensors could be attributed to the catalytic effect, large surface area, good electrical conductivity and physicochemical nature. Notably, the electrocatalytic performances of the SDZ sensors are good as compared to the previous literature, indicating the significance of the newly designed SrWO₄ modified electrode. The real-sample diagnosis by the SDZ detection in environmental sample demonstrates the proposed SrWO₄-based sensors with good recovery range.

Temperature-gradient incubation isolates multiple competitive species from a single environmental sample

High-throughput sequencing has allowed culture-independent investigation into a wide variety of microbiomes, but sequencing studies still require axenic culture experiments to determine ecological roles, confirm functional predictions and identify useful compounds and pathways. We have developed a new method for culturing and isolating multiple microbial species with overlapping ecological niches from a single environmental sample, using temperature-gradient incubation. This method was more effective than standard serial dilution-to-extinction at isolating methanotrophic bacteria. It also highlighted discrepancies between culture-dependent and -independent techniques; 16S rRNA gene amplicon sequencing of the same sample did not accurately reflect cultivatable strains using this method. We propose that temperature-gradient incubation could be used to separate out and study previously ‘unculturable’ strains, which co-exist in both natural and artificial environments.

Determination of sulfa antibiotic residues in river and particulate matter by field-amplified sample injection-capillary zone electrophoresis

In the present research, field-amplified sample injection-CZE (FASI-CZE) coupled with a diode array detector was established to determine trace level sulfa antibiotic. Sulfathiazole, sulfadiazine, sulfamethazine, sulfadimethoxine, sulfamethoxazole, and sulfisoxazole were selected as analytes for the experiments. The background electrolyte solution consisted of 70.0 mmol/L borax and 60.0 mmol/L boric acid (including 10% methanol, pH 9.1). The plug was 2.5 mmol/L borax, which was injected into the capillary at a pressure of 0.5 psi for 5 s. Then the sample was injected into the capillary at an injection voltage of -10 kV for 20 s. The electrophoretic separation was carried out under a voltage of +19 kV. The capillary temperature was maintained at 20˚C throughout the analysis, and six sulfonamides were completely separated within 35 min. Compared with pressure injection-CZE, the sensitivity of FASI-CZE was increased by 6.25-10.0 times, and the LODs were reduced from 0.2-0.5 to 0.02-0.05 μg/mL. The method was applied to the determination of sulfonamides in river water and particulate matter samples. The recoveries were 78.59-106.59%. The intraday and interday precisions were 2.89-7.35% and 2.77-7.09%, respectively. This provides a simpler and faster method for the analysis of sulfa antibiotic residues in environmental samples.

Facile preparation of reduced graphene oxide/ZnFe2O4 nanocomposite as magnetic sorbents for enrichment of estrogens

Reduced graphene oxide/ZnFe₂O₄ (rGO/ZnFe₂O₄) nanocomposite was facile prepared and applied as magnetic sorbent for the extraction of estrogens including 17β-estradiol, 17α-estradiol, estrone and hexestrol from water, soil, and fish samples prior to HPLC analysis. The rGO/ZnFe₂O₄ nanocomposite was characterized by scanning electron microscope, Fourier transform-infrared spectroscopy, X-ray diffraction, and vibrating sample magnetometer. The experimental parameters affecting the efficiency of magnetic solid-phase extraction (MSPE) including the amount of material, extraction time, pH, temperature, desorption solvents, desorption time, and desorption solvent volume were investigated respectively. With the developed method, good linearity was observed in the range of 0.05-500 ng/mL with the correlation coefficients (R²) between 0.9978 and 0.9993. The limits of detection (S/N = 3) and limits of quantification (S/N = 10) were achieved at 0.01-0.02 ng/mL and 0.05 ng/mL, respectively. The enrichment factors were calculated as the range of 241-288. Using rGO/ZnFe₂O₄ nanocomposite as the sorbent, the developed MSPE followed by HPLC analysis, was applied to analysis of estrogens in river water, soil and fish samples. The method has the potential application in the extraction and preconcentration ultra trace compounds in complex matrices, such as environmental and biological samples.

Evaluating the net effect of sulfadimidine on nitrogen removal in an aquatic microcosm environment

Antibiotics enter into aquatic pond sediments by wastewater and could make detrimental effects on microbial communities. In this study, we examined the effects of sulfadimidine on nitrogen removal when added to experimental pond sediments. We found that sulfadimidine increased the number of sulfadimidine resistant bacteria and significantly increased the abundance of sul2 at the end of the incubation time (ANOVA test at Tukey HSD, P < 0.05). In addition, sulfadimidine decreased the N₂O reduction rate as well as the amount of nitrate reduction. Pearson correlation analysis revealed that the N₂O reduction rate was significantly and negatively correlated with narG (r = -0.679, P < 0.05). In contrast, we found a significant positive correlation between the amount of nitrate reduction and the abundance of narG (r = 0.609, P < 0.05) and nirK (r = 0.611, P < 0.05). High-throughput sequencing demonstrated that Actinobacteria, Euryarchaeota, Gemmatimonadetes, Nitrospirae, Burkholderiaceae (a family of Proteobacteria), and Thermoanaerobaculaceae (a family of Firmicutes) decreased with sulfadimidine exposure. In sediments, Actinobacteria, Bacteroidetes, Cyanobacteria, Epsilonbacteraeota, Euryarchaeota, Firmicutes, Gemmatimonadetes, and Spirochaetesat may play key roles in nitrogen transformation. Overall, the study exhibited a net effect of antibiotic exposure regarding nitrogen removal in an aquatic microcosm environment through a combination of biochemical pathways and molecular pathways, and draws attention to controlling antibiotic pollution in aquatic ecosystems.

Rapid and versatile pre-treatment for quantification of multi-walled carbon nanotubes in the environment using microwave-induced heating

The concerns regarding potential environmental release and ecological risks of multi-walled carbon nanotubes (MWCNTs) rise with their increased production and use. As a result, there is the need for an analytical method to determine the environmental concentration of MWCNTs. Although several methods have been demonstrated for the quantification of well-characterized MWCNTs, applying these methods to field samples is still a challenge due to interferences from unknown characteristics of MWCNTs and environmental media. To bridge this gap, a recently developed microwave-induced heating method was investigated for the quantification of MWCNTs in field samples. Our results indicated that the microwave response of MWCNTs was independent of the sources, length, and diameter of MWCNTs; however, the aggregated MWCNTs were not able to convert the microwave energy to heat, making the method inapplicable. Thus, a pre-treatment process for dispersing bundled MWCNTs in field samples was crucial for the use of the microwave method. In the present paper, a two-step pre-treatment procedure was proposed: the aggregated MWCNTs loaded environmental samples were first exposed to high temperature (500 °C) and then dispersed by using an acetone-surfactant solution. A validation study was performed to evaluate the effectiveness of the pre-treatment process, showing that an 80-120% recovery range of true MWCNT loading successfully covered the microwave-measured MWCNT mass.

Metaproteomics of Freshwater Microbial Communities

Recent advances in metaproteomics have provided us a link between genomic expression and functional characterization of environmental microbial communities. Therefore, the large-scale identification of proteins expressed by environmental microbiomes allows an unprecedented view of their in situ metabolism and function. However, one of the main challenges in metaproteomics remains the lack of robust analytical pipelines. This is especially true for aquatic environments with low protein concentrations and the presence of compounds that are known to interfere with traditional sample preparation pipelines and downstream LC-MS/MS analyses. In this chapter, a semiquantitative method that spans from sample preparation to functional annotation is provided. This method has been shown to provide in-depth and representative results of both the eukaryotic and prokaryotic fractions of freshwater microbiomes.

Development of an advanced electrochemical biosensing platform for E. coli using hybrid metal-organic framework/polyaniline composite

Because of numerous merits (e.g., the possibility of their synthesis in 1-D, 2-D, and 3-D forms, large surface-to-volume ratio, and flexible framework functionality), metal-organic frameworks (MOFs) are envisaged as excellent media for the development of biosensors for diverse analytes present in environmental media. The present research work, for the first time, reports the development of a Cu-MOF based electrochemical biosensor for highly sensitive detection of E. coli bacteria. In order to realize an MOF-based electrochemically active platform, Cu₃(BTC)₂ (BTC = 1,3,5-benzenetricarboxylic acid) was mixed with polyaniline (PANI). The spectroscopic/morphological characterizations of the resulting composite were established with the aid of FT-IR, UV-visible spectroscopy, X-ray diffraction, electron microscopy, and surface area analysis. The thin films of Cu₃(BTC)₂-PANI, on an indium-tin oxide (ITO) substrate, were bio-interfaced with anti-E. coli antibodies for use as a novel biosensing electrode. Based on the electrochemical impedance spectroscopy (EIS) technique of signal measurement, the above sensor exhibited high sensitivity to detect very low concentrations of E. coli (2cfu/mL) in a short response time (~2 min) and was also selective in the presence of other non-specific bacteria. As a novel highlight of the research, this new MOF/PANI based detection platform for E. coli has shown improved performance than many of the previously reported electrochemical biosensors.

The prevalence of Francisella spp. in different natural surface water samples collected from northwest of Iran

BACKGROUND AND OBJECTIVES

Francisella tularensis has a wide distribution in northern hemisphere of the world. Up to now, there was little information about the Francisella spp. situation in the environmental samples in Iran. In this study we aimed to determine the prevalence of Francisella spp. in the environmental samples in northwest of Iran.

MATERIALS AND METHODS

A total of 237 natural water samples from ponds, rivers, lakes, springs and other surface waters from north western provinces of Iran (Kurdistan and Western Azerbaijan) were collected from September to November 2015. All samples were cultured for Francisella and other bacterial species and Real Time TaqMan PCR was performed on the concentrated and DNA extracted samples. For detection of the presence of bacterial DNA in the samples, two different targets in the genome of Francisella, ISFtu2 and fopA were used.

RESULTS

Among the tested surface water samples, 40 (17.09%; 95% CI: 12.67-22.33%) and 12 (5.13%; 95%CI: 2.81-8.56%) samples were positive for ISFtu2 and fopA respectively. None of them was positive in culture.

CONCLUSION

The prevalence of Francisella spp. in the environmental samples in the west of Iran is high and it is comparable with Turkey, Iran's neighboring country. Use of higher copy number genes or IS like ISFtu2 could improve the detection of this organism in the environmental samples.

Degradation of propyl paraben by activated persulfate using iron-containing magnetic carbon xerogels: investigation of water matrix and process synergy effects

An advanced oxidation process comprising an iron-containing magnetic carbon xerogel (CX/Fe) and persulfate was tested for the degradation of propyl paraben (PP), a contaminant of emerging concern, in various water matrices. Moreover, the effect of 20 kHz ultrasound or light irradiation on process performance was evaluated. The pseudo-first order degradation rate of PP was found to increase with increasing SPS concentration (25-500 mg/L) and decreasing PP concentration (1690-420 μg/L) and solution pH (9-3). Furthermore, the effect of water matrix on kinetics was detrimental depending on the complexity (i.e., wastewater, river water, bottled water) and the concentration of matrix constituents (i.e., humic acid, chloride, bicarbonate). The simultaneous use of CX/Fe and ultrasound as persulfate activators resulted in a synergistic effect, with the level of synergy (between 35 and 50%) depending on the water matrix. Conversely, coupling CX/Fe with simulated solar or UVA irradiation resulted in a cumulative effect in experiments performed in ultrapure water.

Functional and taxonomic classification of a greenhouse water drain metagenome

Microbiome sequencing has become the standard procedure in the study of new ecological and human-constructed niches. To our knowledge, this is the first report of a metagenome from the water of a greenhouse drain. We found that the greenhouse is not a diverse niche, mainly dominated by Rhizobiales and Rodobacterales. The analysis of the functions encoded in the metagenome showed enrichment of characteristic features of soil and root-associated bacteria such as ABC-transporters and hydrolase enzymes. Additionally, we found antibiotic resistances genes principally for spectinomycin, tetracycline, and aminoglycosides. This study aimed to identify the bacteria and functional gene composition of a greenhouse water drain sample and also provide a genomic resource to search novel proteins from a previously unexplored niche. All the metagenome proteins and their annotations are available to the scientific community via http://microbiomics.ibt.unam.mx/tools/metagreenhouse/.

Highly selective and sensitive determination of Cu2+ in drink and water samples based on a 1,8-diaminonaphthalene derived fluorescent sensor

A new simple and efficient fluorescent sensor L based on 1,8‑diaminonaphthalene Schiff-base for highly sensitive and selective determination of Cu²⁺ in drink and water has been developed. This Cu²⁺-selective detection over other tested metal ions displayed an obvious color change from blue to colorless easily detected by naked eye. The detection limit is determined to be as low as 13.2 nM and the response time is very fast within 30 s. The 1:1 binding mechanism was well confirmed by fluorescence measurements, IR analysis and DFT calculations. Importantly, this sensor L was employed for quick detection of Cu²⁺ in drink and environmental water samples with satisfactory results, providing a simple, rapid, reliable and feasible Cu²⁺-sensing method.

Occurrence of Acanthamoeba genotypes in Central West Malaysian environments

Acanthamoeba species are ubiquitous free-living protozoa that can be found worldwide. Occasionally, it can become parasitic and the causative agent of acanthamoebic keratitis (AK) and Granulomatous Amoebic Encephalitis (GAE) in man. A total of 160 environmental samples and 225 naturally-infected animal corneal swabs were collected for Acanthamoeba cultivation. Acanthamoeba was found to be high in samples collected from environments (85%, 136/160) compared to infected animal corneas (24.89%, 56/225) by microscopic examination. Analysis of nucleotide sequence of 18S rRNA gene of all the 192 cultivable Acanthamoeba isolates revealed 4 genotypes (T3, T4. T5 and T15) with T4 as the most prevalent (69.27%, 133/192) followed by T5 (20.31%), T15 (9.90%) and T3 (0.52%). Genotype T4 was from the strain of A. castellanii U07401 (44.27%), A. castellanii U07409 (20.83%) and A. polyphagaAY026243 (4.17%), but interestingly, only A. castellanii U07401 was detected in naturally infected corneal samples. In environmental samples, T4 was commonly detected in all samples including dry soil, dust, wet debris, wet soil and water. Among the T4, A. castellanii (U07409) strains were detected high occurrence in dry (45%) followed by aquatic (32.50%) and moist (22.50%) samples but however A. castellanii (U07401) strains were dominant in dry samples of soil and dust (93.10%). Subsequently, genotype T5 of A. lenticulata (U94741) strains were dominant in samples collected from aquatic environments (58.97%). In summary, A. castellanii (U07401) strains were found dominant in both environmental and corneal swab samples. Therefore, these strains are possibly the most virulent and dry soil or dusts are the most possible source of Acanthamoeba infection in cats and dogs corneas.

The efficiency of the multi-walled carbon nanotubes used for antibiotics removal from wastewaters generated by animal farms

In the recent years, residual antibiotics are considered to be emerging environmental pollutants due to their continuous input and persistence into the aquatic ecosystem even at low concentrations. Therefore, these are necessary to develop efficient methods for the wastewater treatment. The present paper describes the efficiency of several types of multi-walled carbon nanotubes (MWCNTs) for the retention of the selected antibiotics (ampicillin, ceftazidime, cefepime, imipenem, piperacillin, tazobactam, tetracycline, erythromycin, ciprofloxacin, norfloxacin, vancomycin, gentamicin, sulfamethoxazole, and thrimetoprim) from aqueous (synthetic) solutions and wastewater samples. The functionalized MWCNTs were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The obtained antibiotic percentage of retention was evaluated by quantitative assessment using high-performance liquid chromatography coupled with the diode array, fluorescence, and mass spectrometer detector (HPLC-DAD/FD/MS), after the solid-phase extraction (SPE) with Oasis HLB cartridges. The retention percentages of the selected antibiotics from waters ranged between ∼40 and 97%, with the exception of sulfamethoxazole and trimethoprim. The best percentages of retention were obtained for norfloxacin 97.03% and ciprofloxacin 97.10%. The suspensions of the MWCNTs improved the antibiotics removal from wastewaters. Removal of antibiotics from wastewaters using nanotechnology, in order to reduce their negative effects and antibiotic resistance, is a promising tool in the future wastewaters treatment.

First results of a simultaneous measurement of tritium and (14)C in an ultra-low-background proportional counter for environmental sources of methane

Simultaneous measurement of tritium and (14)C would provide an added tool for tracing organic compounds through environmental systems and is possible via beta energy spectroscopy of sample-derived methane in internal-source gas proportional counters. Since the mid-1960's atmospheric tritium and (14)C have fallen dramatically as the isotopic injections from aboveground nuclear testing have been diluted into the ocean and biosphere. In this work, the feasibility of simultaneous tritium and (14)C measurements via proportional counters is revisited in light of significant changes in both the atmospheric and biosphere isotopics and the development of new ultra-low-background gas proportional counting capabilities for small samples (roughly 50 cc methane). A Geant4 Monte Carlo model of a Pacific Northwest National Laboratory (PNNL) proportional counter response to tritium and (14)C is used to analyze small samples of two different methane sources to illustrate the range of applicability of contemporary simultaneous measurements and their limitations. Because the two methane sources examined were not sample size limited, we could compare the small-sample measurements performed at PNNL with analysis of larger samples performed at a commercial laboratory. These first results show that the dual-isotope simultaneous measurement is well matched for methane samples that are atmospheric or have an elevated source of tritium (i.e. landfill gas). However, for samples with low/modern tritium isotopics (rainwater), commercial separation and counting is a better fit.

Quantification for total demethylation potential of environmental samples utilizing the EGFP reporter gene

The demethylation potential of pollutants is arguably an innate component of their toxicity in environmental samples. A method was developed for determining the total demethylation potential of food samples (TDQ). The demethylation epigenetic toxicity was determined using the Hep G2 cell line transfected with pEGFP-C3 plasmids containing a methylated promoter of the EGFP reporter gene. The total demethylation potential of the sample extracts (the 5-AZA-CdR demethylation toxic equivalency) can be quantified within one week by using a standard curve of the 5-AZA-CdR demethylation agent. To explore the applicability of TDQ for environmental samples, 17 groundwater samples were collected from heavy polluted Kuihe river and the total demethylation potentials of the sample extracts were measured successfully. Meaningful demethylation toxic equivalencies ranging from 0.00050 to 0.01747μM were found in all groundwater sample extracts. Among 19 kinds of inorganic substance, As and Cd played important roles for individual contribution to the total demethylation epigenetic toxicity. The TDQ assay is reliable and fast for quantifying the DNA demethylation potential of environmental sample extracts, which may improve epigenetic toxicity evaluations for human risk assessment, and the consistent consuming of groundwater alongside the Kuihe river pose unexpected epigenetic health risk to the local residents.

Method validation and uncertainty evaluation of organically bound tritium analysis in environmental sample

The analytical method for organically bound tritium (OBT) was developed in our laboratory. The optimized operating conditions and parameters were established for sample drying, special combustion, distillation, and measurement on a liquid scintillation spectrometer (LSC). Selected types of OBT samples such as rice, corn, rapeseed, fresh lettuce and pork were analyzed for method validation of recovery rate reproducibility, the minimum detection concentration, and the uncertainty for typical low level environmental sample was evaluated. The combustion water recovery rate of different dried environmental sample was kept at about 80%, the minimum detection concentration of OBT ranged from 0.61 to 0.89 Bq/kg (dry weight), depending on the hydrogen content. It showed that this method is suitable for OBT analysis of environmental sample with stable recovery rate, and the combustion water yield of a sample with weight about 40 g would provide sufficient quantity for measurement on LSC.