Lake Water Samples Research Articles

Fabrication and characterization of 4-aminoantipyrine electrospun nanofiber polymer membranes for rapid visualization of pentachlorophenol in water samples

In this work, we pioneered the development of a novel 4-aminoantipyrine loaded polylactic acid electrospun membrane for visualization and rapid detection of pentachlorophenol in water samples. The morphology, pH value, selectivity and detection sensitivity of electrospun membranes were systematically studied and optimized. The study found that the detection limit of the electrospun nanofiber polylactic acid membrane loaded with 4-aminoantipyrine was 0.4 mg/L, and the effective detection time was 0.5 h. The membranes have good stability after one month of storage in the dark at room temperature, the selectivity of 4-aminoantipyrineloaded polylactic acid electrospun membranes to other and its analogs in aqueous environment was then compared. The actual sample (including drinking water, tap water used in our lives, lake water and temporary water samples collected during production, transportation and distribution of fish) test result is negative. The fast-response electrospun nanofiber polylactic acid membrane loaded with 4-aminoantipyrine have available detection limits, simple detection methods, fast detection times, no secondary contamination of the solution to be tested, and the amount of sample required extremely small, showed great potential for materials science, environmental monitoring and food safety inspection.

Carbon Nanodots with Solvatochromic Photoluminescence for the Electrochemical Determination of Estrogenic Steroids

Herein, we utilized carbon nanodots (R-CNDs) for the electrochemical detection of estrogens in tap and natural water samples and simulated effluents from Swedish waste water treatment plants (WWTPs). R-CNDs were prepared from 2-aminophenol by solvothermal synthesis and used as a modifier for chitosan-based selective membranes. The data obtained from atomic force microscopy and transmission electron microscopy suggest a spherical morphology of the R-CNDs with lateral size in the range of 3–8 nm and the height of 1–8 nm. In contrast to most other known carbon nanodots, R-CNDs are soluble in various organic solvents, including apolar, and less soluble in water. Small nanodots (3 nm) are more hydrophilic than large ones (6–8 nm) and can be separated from the bulk suspension of R-CNDs in heptane by their extraction into a water/ethanol mixture. Suspensions of large R-CNDs in apolar solvents exhibit green photoluminescence, while small R-CNDs in polar solvents have orange. This phenomenon was attributed to a solvatochromic rather than to a quantum effect. The R-CNDs were embedded on a chitosan-modified pencil electrode and the electrode was applied for voltammetric determination of four abandoned estrogens: estrone, estradiol, estriol, and ethynyl estradiol. The sensor demonstrates a group-selective response to the estrogens with a detection limit of 17.0 nmol L–1. It can be applied to determine the estrogens in the range of 0.05–4.6 μmol L–1 in the presence of typical interfering bioactive compounds, such as paracetamol, uric acid, progesterone, sulfamethoxazole, trimethoprim, ibuprofen, and caffeine. The developed sensors show repeatability and reproducibility values of 1.8–3.4% and 4.3%, respectively. The efficiency was proved by application for tap and lake water samples, where the recovery range was found to be 93–100%. The low cost, stability, and high sensitivity and selectivity of fabricated sensors make R-CNDs a perspective modifier for electrochemical sensors for the detection of estrogen microquantities in variable water samples.

Using immune cell-based bioactivity assays to compare the inflammatory activities of oil sands process-affected waters from a pilot scale demonstration pit lake

In this study, we provide evidence that oil sands process-affected waters (OSPW) contain factors that activate the antimicrobial and proinflammatory responses of immune cells. Specifically, using the murine macrophage RAW 264.7 cell line, we establish the bioactivity of two different OSPW samples and their isolated fractions. Here, we directly compared the bioactivity of two pilot scale demonstration pit lake (DPL) water samples, which included expressed water from treated tailings (termed the before water capping sample; BWC) as well as an after water capping (AWC) sample consisting of a mixture of expressed water, precipitation, upland runoff, coagulated OSPW and added freshwater. Significant inflammatory (i.e. macrophage activating) bioactivity was associated with the AWC sample and its organic fraction (OF), whereas the BWC sample had reduced bioactivity that was primarily associated with its inorganic fraction (IF). Overall, these results indicate that at non-toxic exposure doses, the RAW 264.7 cell line serves as an acute, sensitive and reliable biosensor for the screening of inflammatory constituents within and among discrete OSPW samples.

Ultrasensitive detection of silver(I) ions based on water-soluble micellized phosphorescent silver nanoclusters co-protected by 1,3-benzenedithiol and triphenylphosphine

Silver ion (Ag+) is one of the most toxic and dangerous heavy metal pollutants. Therefore, finding a simple, sensitive and selective approach to detect Ag+ is very urgent for environmental protection and risk reduction to human health. In this work, water-soluble red-emitting micellized phosphorescent silver nanoclusters (Ag29 @Na micelles) with a large stokes shift of 380 nm are prepared and used as sensitive and selective phosphorescent probes to realize the rapid and simple detection of Ag+. Upon adding Ag+, the phosphorescence of Ag29 @Na micelles is quenching, and the phosphorescence quenching ratio is linearly proportional to the Ag+ concentration over the range from 1 nM to 100 nM with the detection limit of 0.8 nM (S/N = 3). The Ag29 @Na micelles exhibit high selectivity for Ag+ over other potentially interfering metal ions. The quenching mechanism of Ag29 @Na micelles by Ag+ is studied in details using various analytical characterizations including UV–vis absorption spectroscopy, photoluminescence lifetime, X-ray photoelectron spectroscopy, transmission electron microscopy, and zeta potential, and the results denote that the aggregation between Ag29 @Na micelles and Ag+ is responsible for the phosphorescence quenching. The Ag29 @Na micelles-based phosphorescence probes are successfully applied to detect Ag+ in lake water samples with good recoveries of 98 %−108 %.

Potentially toxic elements contamination, risk assessment via consumption, and spatial distribution of pollution and evaluation indices in the alpine lakes, Pakistan

ABSTRACT The current study investigated potentially toxic elements (PTE) contaminations in the water of alpine lakes of Gilgit-Baltistan, Northern Pakistan. Water samples (n = 46) of various alpine lakes were collected and analysed for PTE determination through atomic absorption spectroscopy (AAanalyst 700, PerkinElmer, USA). Arsenic (As) in water was measured using a mercury hydride generation system. PTE concentrations in water of alpine lakes were observed below the upper limit of the world health organisation (WHO) drinking water guidelines, except for iron (Fe, 14%), chromium (Cr, 10%), and As (2%) of samples. The highest mean concentrations of Fe (233 ± 22.4 µg/L) and Cr (36.3 ± 4.20 µg/L) were noted in the water of Rama Lake and the As (6.20 ± 0.65 µg/L) in the Lower Kachura Lake. PTE concentrations in the water of alpine lakes was evaluated for the elements pollution index (EPI), elements evaluation index (EEI), and risk indices. The values of EPI and EEI for PTE in the water of alpine lakes were found far below the threshold limits. Higher mean chronic daily intake (CDI) values were observed for Fe and zinc (6.67 ± 1.09 and 4.95 ± 2.65 µg/kg-day) in the Rama and Upper Kachura Lakes, respectively. Determined hazard quotient (HQ) values for PTE were noted as> 1. However, the HQ value for As was (1.4 ± 0.06) which may have a detrimental effect on the health of children. Cancer risk of As and HQ values for other elements were found within the allowable limits of consumption in drinking water. Statistical analysis revealed that geogenic sources are the main PTE contaminations contributors in the water of alpine lakes.

Silver doped dodecahedral metal-organic framework anchored RGO nanosheets for nanomolar quantification of priority toxic pollutant in aquatic environment

Detection of hazardous environmental pollutants to maintain safety is a significant concern worldwide. In this work, we developed a reliable and sensitive electrochemical sensor for the effective detection of a priority toxic pollutant, 4-nitrophenol (4NP), in the aquatic environment. A ternary nanocomposite was sonochemically prepared by anchoring silver nanoparticles doped rhombic dodecahedral zeolitic imidazolate framework-67 (ZIF-67) on reduced graphene oxide (RGO) nanosheets. We employed a solvothermal method in the preparation of ZIF-67, and the graphene oxide prepared by the Hummer’s method was chemically reduced using ascorbic acid. Important characterization techniques including XRD, SEM, elemental mapping, TEM, XPS, BET, Raman spectroscopy, FTIR, and EIS were used for evaluating properties of the synthesized nanomaterials. The prepared porous ternary nanocomposite evinced outstanding electrocatalytic activity towards 4NP determination, and the developed 4NP sensor showcased a very low detection limit of 0.3 nM and high sensitivity of 65.49 μAμM−1 cm−2. Furthermore, significant performance criterions, including stability, reproducibility, anti-interference, and repeatability were examined to prove the reliability of the proposed sensor in 4NP quantification. The practical feasibility of the developed 4NP sensor was also evaluated by carrying out experiments with river water, lake water, and underground water samples.

Excluding interference and detecting Microcystin-LR in the natural lakes and cells based a unique fluorescence method

Cyanobacteria blooms that cause the death of aquatic and terrestrial organisms have attracted considerable attention since the 19th century. The most typical toxin in cyanobacteria blooms is cyanobacteria toxin, particularly microcystin-LR (MC-LR). Therefore, a simple and highly efficient method for detecting MC-LR plays a role in studying the ecological toxicology of MC-LR. However, as MC-LR itself is located in a complex environment, traditional techniques present complex and false-positive defects. To address the above issues, novel technologies should be explored and discovered. Herein, we describe the development of MC-BDKZ as the first paradigm of probes that can concurrently report MC-LR in natural lakes and cells. This novel material shows large Stokes Shift and possesses good photostability and high sensitivity. Considering the properties mentioned above, MC-BDKZ not only achieves the detection of MC-LR in the lake water samples, but also completes the imaging of exogenous MC-LR in cells. Moreover, the interference of many factors in the lake and cells is excluded completely in the process of MC-LR detection. We comprehensively analyzed the response principle and potential application of MC-BDKZ in the process of MC-LR detection. Compared with the conventional MC-LR detection technologies, fluorescence probe technology shows better convenience and greatly reduces distance from the practical application in vitro and in vivo. We envisioned that the development of this visual research tool could provide crucial clues for exploring the pathogenesis of MC-LR in body.

Facile synthesis of sulfur and oxygen co-doped graphitic carbon nitride quantum dots for on-off detection of Cu2+ in real samples and living cells

A fluorescent sulfur and oxygen co-doped graphitic carbon nitride quantum dots (S,O-CNQDs) were prepared from ethylenediaminetetraacetic acid disodium salt dihydrate and thiourea as the carbon and sulfur sources. The morphology and surface functional groups of S,O-CNQDs were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The fluorescence of S,O-CNQDs could be quenched efficiently by Cu2+ under the optimum conditions. The S,O-CNQDs could function as an excellent fluorescent probe for Cu2+ detection with a wide linear range of 0.50–15 μM and a low detection limit of 0.58 nM. In addition, this fluorescent probe was employed for monitoring Cu2+ in samples of tap water, lake water, human serum and urine with good recoveries from 99.0% to 110.0%. Moreover, the S,O-CNQDs with high cell penetration and low cytotoxicity were utilized for Cu2+ detection in living cells. Owing to the excellent properties of S,O-CNQDs, the as-prepared S,O-CNQDs can be a potential candidate for biological applications.

Assessment of Bhatiari Lake water quality: Pollution indices, hydrochemical signatures and hydro-statistical analysis

This study aimed at evaluating the water quality of Bhatiari Lake (BL) for the first time based on water quality parameters, pollution indices, hydrochemical signatures and hydro-statistical analysis. Lake water samples were collected from the lake during April–May 2019 and wide ranges of parameters were considered for the investigation. Except for COD and Fe, all the parameters were within the permissible limit. COD crossed Bangladesh standards and testing institution (BSTI) and United States environmental protection agency (USEPA) standards. In contrast, Fe crossed World health organization (WHO), Bureau of Indian Standards (BIS) and USEPA standards. Hydrochemical analysis indicated the water as soft-fresh where near neutral low-metal was noticed from the Ficklin-Caboi diagram. Ca2+-Mg2+-HCO3- type water was confirmed from Piper and Chadha diagram, whereas Durov and Schoeller's diagram were indicated the influence of Mg2+-HCO3-. The trend of cations and anions were Ca2+> Mg2+> Na+>K+ and HCO3− > Cl− > NO3− > SO42− > PO43− as stated by pie chart. Most precipitation dominant water was confirmed from the Gibbs diagram. Principal component analysis (PCA), Cluster analysis (CA) and Correlation matrix (CM) indicated the co-existence of geogenic and anthropogenic sources for pollution. Good water quality was observed via an integrated approach namely degree of contamination (Cd), Single-Factor Pollution Index (SPI), Comprehensive pollution index (CPI), Heavy metal evaluation index (HEI), Heavy metal pollution index (HPI), Nemerow's pollution index (NPI) and Ecological risk index (ERI). In addition, water quality index (WQI) remarked the water is excellent. Taken collectively, the present study indicates the BL water can be considered pollution-free.

EIS biosensor based on a novel Myoviridae bacteriophage SEP37 for rapid and specific detection of Salmonella in food matrixes

Recently, using bacteriophages as new molecular probes in reliable platforms for the detection of bacterial pathogens has attracted more and more increasing attentions. In this paper, a novel isolated Myoviridae bacteriophage SEP37 was covalently immobilized onto gold nanoparticles (AuNPs) modified gold disk electrode (GDE) surfaces using cysteamine (Cys) as a crosslinker. Substrates of GDE-AuNPs-Cys-Phage SEP37 and specific capture of Salmonella cells had been characterized using scanning electron microscopy (SEM) separately. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to study the electrochemical response of the biosensor interface manufacturing and bacterial capture process. Under the optimal experimental conditions, this phage-based EIS biosensor was able to detect Salmonella with a wide linear range from 2 × 101 to 2 × 106 colony forming unit (CFU)/mL within 30 min in spiked lake water and lettuce samples, with a limit of detection (LOD) of 17 CFU/mL. The detection linear range of spiked chicken samples was 2 × 102 to 2 × 105 CFU/mL, with a LOD of 1.3 × 102 CFU/mL. In combination with a pre-enrichment process for 3.5 h, this assay could reach a LOD of 1 CFU/mL in chicken breast meat samples. Besides, this phage-based EIS biosensor provided good reproducibility and stability. This phage-based EIS biosensor opens a new opportunity for the detection of pathogenic bacteria using the inherent selectivity of bacteriophage recognition.

Rapid preparation of melamine based magnetic covalent triazine polymers for highly efficient extraction of copper(II), chromium(III) and lead(II) ions from environmental and biological samples

In this work, melamine based magnetic covalent triazine polymers (MCTPs) was prepared by decoration of melamine based triazine polymers on the surface of magnetic Fe3O4@SiO2 nanoparticles. The polymer decoration is realized by nucleophilic substitution reaction between melamine (as functional monomer) and 1,4-dibromobutane (as crosslinking agent), which is simple, rapid and cost effective. The resultant MCTPs showed good affinity toward Cu2+, Cr3+ and Pb2+ with fast adsorption kinetic (7 min) and high adsorption capacities (38.3, 33.9 and 49.7 mg g−1 for Cu2+, Cr3+ and Pb2+, respectively). Besides, the prepared MCTPs can be reused after adsorption, desorption and regeneration steps, and the phase separation is highly efficient with the addition of an external magnet. Thus, MCTPs was employed as a magnetic solid-phase extraction (MSPE) sorbent for the extraction of trace Cu2+, Cr3+ and Pb2+ followed by graphite furnace atomic absorption spectrometry (GFAAS) determination. Then the extraction conditions of the above-mentioned MSPE-GFAAS method were optimized, including sample pH, extraction/elution time, sample volume, etc. Under the optimized conditions, the MCTPs based MSPE-GFAAS method exhibit the following merits: short extraction/elution time (10/3 min), high enrichment factor (125 folds) and low detection limit (2.9, 1.4 and 6.1 ng L-1 for Cu2+, Cr3+ and Pb2+, respectively). Finally, the proposed method was successfully employed for the determination of trace Cu2+, Cr3+ and Pb2+ in tap water, river water, lake water, human urine and human hair samples. The adequate recoveries of 85 ∼ 105% in spiked samples were achieved, suggesting the promising potential of MCTPs based MSPE-GFAAS method as an effective method for evaluating the environment and biological effect of metal ions.

Synthesis of biocompatible Konjac glucomannan stabilized silver nanoparticles, with Asystasia gangetica phenolic extract for colorimetric detection of mercury (II) ion

Herein, the synthesis of a biocompatible silver nanoparticles (AgNPs), for colorimetric detection of toxic mercury (II) ion (Hg2+), is reported. Phenolic-rich fraction of Asystasia gangetica leaf was extracted and used as a reductant of silver salt, all within the hydrophilic konjac glucomannan (KgM) solution as stabilizer, at room temperature (RT). The bioactive components of Asystasia gangetica phenolic extract (AGPE), as elucidated with a (UHPLC-MS-QTOF-MS), revealed plethora of phenolic compounds, which can facilitate the reduction of silver salt at ambient conditions. Sparkling yellow colloidal solution of KgM-AgNPs was realized within 1 h, at RT, having a UV–vis maximum at 420 nm. KgM-AgNPs was characterized using UV–vis, Raman and (FTIR), TEM, SEM, EDS, XRD, TGA/DTG. TEM and FESEM images showed that KgM-AgNPs were spherical, with particle size distribution around 10–15 nm from TEM. The KgM-AgNPs biocompatibility was investigated on mouse L929 fibrobroblast and rat erythrocytes, without any harmful damages on the tested cells. In aqueous environment, KgM-AgNPs demonstrated good detection capacity toward Hg2+, in a Hg2+ concentration dependent fashion, within 3 min. Absorbance ratios (A360/A408) was linear with Hg2+ concentrations from 0.010–10.0 to 10.0–60.0 µM, with an estimated (LOD) of 3.25 nM. The probe was applied in lake water sample, with satisfactory accuracy.

Mechanochromic and AIE active fluorescent probes for solution and vapor phase detection of picric acid: Application of logic gate

Development of organic probes through simple synthetic methodology with exceptional fluorescence properties in aqueous media, strong resistance to photobleaching, and diverse applications in solutions and vapor phase sensing are inevitably pivotal. Herein, fluorene based aggregation induced emission (AIE) active probes SM1 and SM2 were developed through a single-step Knoevenagel condensation reaction. Probes exhibited distinguished solvatochromism and reversible mechanochromism. AIE active probes SM1 and SM2 were further applied for the rapid solution-phase detection of picric acid (PA) through excellent fluorescence quenching with LOD down to 2.09 and 3.65 nM, respectively, where PET and FRET featured as vital sensing mechanisms. The sensing mechanism was supported through density functional theory (DFT) and dynamic light scattering (DLS) analyses. Probes also demonstrated the quick naked-eye colorimetric detection of PA. Dip coated fluorescent films were conveniently constructed for the efficient vapor phase and paper based detection of PA. Besides, AIE active probes were effectively employed for the quantitative recognition of PA in river and lake water samples. An INHIBIT logic device was also fabricated via the UV–visible response of probes for PA.

Algal Diversity of a Freshwater Lake of Tumkur City, Karnataka, India

Water is a universal solvent, where almost all the living being’s carry out their biochemical reactions. Fresh water usually contains nutrients for all types of microorganisms, one of which, algae found commonly inlakes. Phosphorous and nitrates are the principal nutrient for algae. The study of algal diversity in freshwater is very useful to determine quality of water and nature of aquatic ecosystem. Amanikere lake inTumakuru city is one of the major lakes to receive residential sewage. Water samples were collected for thestudy of diversity of algae from June, 2017 to May, 2018. The algal samples were isolated and identifiedusing standard laboratory method of Clesceri et al., (1998). About 38 species of algae were found in randomly selected areas (1 to 6) of water samples of Amanikere lake. Some of the algae found to be in high in Amanikere lake like Cyanophyceae – Oscillatoria, Nostoc, Anabaena., Chlorophyceae – Spirogyra, CosmeriumandBacillariophyceae – Navicula, Diatoma, Fragellaria. The study carried out reveals a diversity of algae in the lake.

A detailed study of diatoms a Bacillariophyta community from Rewalsar and Prashar lakes of Himachal Pradesh, their bio-monitoring characteristics and forensic significance

Diatoms are ubiquitous, unicellular, siliceous walled, aquatic, autotrophic in nature and a part ofBacillariophyceae class of algae. Diatoms are ecologically very much helpful. They act as a very good Biomonitoring agents. Their sensitive character towards the environmental factors makes them a monitor.Diatoms shows their affect towards temperature, chloride content, Ammonia and Biochemical oxygendemand quantity. The species are studied from water samples of Rewalsar and Prashar lakes of HimachalPradesh. Diatoms are utilized by forensic investigators in solving the drowning cases occurred due toaccidental or by suicidal modes. So these diatoms are very significant even with forensic angle.

Highly selective and sensitive colorimetric detection for glyphosate based on β-CD@DNA-CuNCs enzyme mimics

A colorimetric assay based on an enzyme-inhibition strategy is promising for the on-site detection of pesticide residues. However, very few works of pesticide detection were reported based on the inhibition toward nanozymes although nanozymes have demonstrated many advantages in sensing various targets. Herein, a facile colorimetric detection for Glyp was developed based on β-CD@DNA-CuNCs enzyme mimics. The β-CD@DNA-CuNCs with high peroxidase-like activity was synthesized using random DNA double strands as template and β-CD as surface ligand. β-CD@DNA-CuNCs could catalyze the H2O2-3,3′,5,5′-tetramethylbenzidine (TMB) system. The oxidation product OxTMB with a blue color and presented a large absorption signal at 652 nm. However, Glyp could destroy the synergic effect between redox doublet (Cu2+/Cu+) on the β-CD@DNA-CuNCs surface, resulting in the inhibition of the peroxidase-like activity. Colorimetric detection for Glyp could be established by detecting the changes of absorption signal at 652 nm. The linear range was 0.02–2 μg/mL and the detection limit was 0.85 ng/mL (3δ/s). The method was applied in measuring Glyp spiked in lake water and various food samples. This method had rapidness, high sensitivity, and selectivity advantages, indicating the high application potential in monitoring Glyp residue in food.

Nitrogen and copper (Ⅱ) co-doped carbon dots as multi-functional fluorescent probes for Fe3+ ions and tetracycline

This paper synthesized carbon dots (Cu-NCDs) doped with nitrogen and copper, which could be used as a sensor for measurement of Fe3+ and tetracycline (TC). The average particle sizes of CDs and Cu-NCDs were determined as 3.9 nm and 4.8 nm, respectively. The presence of carbon, oxygen, nitrogen and Cu atoms was confirmed in the structure of Cu-NCDs. Both CDs and Cu-NCDs exhibited a strong fluorescence (FL) emission peak at 450 nm, but the doping of Cu and N makes the surface of Cu-NCDs positively charged, which enhances the fluorescence intensity. The carbon dots doped with copper had more significant optical effects than those doped with other metals, and the relative quantum yield (QY) of the Cu-NCDs was as high as 53.6%. Cu-NCDs can be used as multi-functional fluorescent probes to selectively detect Fe3+ and TC based on fluorescence quenching. The limit of detection of Fe3+ and TC separately was found as 1.189 µM and 0.416 µM. This probe is also suitable for the indirect determination of Fe2+ because the Fe2+ is oxidated to Fe3+ by H2O2. The mechanisms of the quenching process for Fe3+ and TC were explored that is the complex process of dynamic quenching and static quenching based on internal filtration effect (IFE), respectively. The fabricated sensors were successfully applied to determine Fe3+ and TC in tap and lake water samples, suggesting a promising application in environment analysis.

Longer amplicons provide better sensitivity for electrochemical sensing of viral nucleic acid in water samples using PCB electrodes

The importance of monitoring environmental samples has gained a lot of prominence since the onset of COVID-19 pandemic, and several surveillance efforts are underway using gold standard, albeit expensive qPCR-based techniques. Electrochemical DNA biosensors could offer a potential cost-effective solution suitable for monitoring of environmental water samples in lower middle income countries. In this work, we demonstrate electrochemical detection of amplicons as long as {503},hbox {bp} obtained from Phi6 bacteriophage (a popular surrogate for SARS-CoV-2) isolated from spiked lake water samples, using ENIG finish PCB electrodes with no surface modification. The electrochemical sensor response is thoroughly characterised for two DNA fragments of different lengths ({117},hbox {bp} and {503},hbox {bp}), and the impact of salt in PCR master mix on methylene blue (MB)-DNA interactions is studied. Our findings establish that length of the DNA fragment significantly determines electrochemical sensitivity, and the ability to detect long amplicons without gel purification of PCR products demonstrated in this work bodes well for realisation of fully-automated solutions for in situ measurement of viral load in water samples.

Development of a Solid-Phase Extraction Method Based on Biocompatible Starch Polyurethane Polymers for GC-MS Analysis of Polybrominated Diphenyl Ethers in Ambient Water Samples.

A new solid-phase extraction (SPE) method for the extraction, enrichment, and analysis of eight polybrominated diphenyl ethers (PBDEs) in water was developed. The current approach involves using a cross-linked starch-based polymer as an extraction adsorbent and determining the PBDE analytes of interest using gas chromatography-mass spectrometry in negative chemical ionization mode (GC-NCI-MS). The starch-based polymer was synthesized by the reaction of soluble starch with 4,4′-methylene-bis-phenyldiisocyanate as a cross-linking agent in dry dimethylformamide. Various parameters impacting extraction efficiencies, such as adsorbent quantity, sample volumes, elution solvents and volumes, and methanol content, were carefully optimized. The 500 mg of starch-based polymer as an adsorbent used to extract 1000 mL of spiked water, presented high extraction recoveries of eight PBDEs. The linearity of the extraction process was investigated in the range of 1–200 ng L−1 for BDE-28, 47, 99, 100, and 5–200 ng L−1 for BDE-153, 154, 183, and 209, with coefficients of determination (r2) exceeding 0.990 for all PBDEs. The limits of detection (LODs) ranged from 0.06 to 1.42 ng L−1 (S/N = 3) and the relative standard deviation values (RSD) were between 3.6 and 9.5 percent (n = 5) under optimum conditions. The method was successfully used to analyze river and lake water samples, where it exhibited acceptable recovery values of 71.3 to 104.2%. Considering the excellent analytical performance and comparative cost advantage, we recommend the developed starch-based SPE method for routine extraction and analysis of PBDEs in water media.

Spontaneously formation of peroxidase mimetics on CuWO4 for homogeneous and universal aptasensing platform

This study addresses the demand for high–performance aptasensing by reporting a spontaneously formed nanozyme on the surface of CuWO4 nanomaterials. The self–coordination of [Fe(CN)6]3- with CuWO4 nanomaterials led to the in situ formation of CuHCF on its surface, which demonstrated efficient peroxidase–like activity for the catalytic oxidation of the chromogenic substrate of 3,3′,5,5′-tetramethylbenzidine (TMB). This spontaneously formed nanozyme enabled its coupling with the stimuli–responsive mesoporous silica nanoparticles (MSN) molecule gates and the nuclease (DNase I) cleavage reaction assisted target recycling for achieving colorimetric aptasensing in label–free, immobilization–free, and highly amplified modes. The developed approach allowed the detection of 0.1–100 nM kanamycin (KANA) with the low detection limit of 3.5 pM, which could also satisfactorily identify the content of KANA in treated milk and lake water samples. The formed nanozyme may in principle be universally applicable for the detection of a range of targets of interest. We hope this spontaneously formed nanozyme would arouse the exploration of more ingenious nanozyme with exquisite biosensing applications.