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In this work, five different magnetic biofilters, containing magnetic nanoparticles (142 nm), immobilized laccase on nanoparticles (190 nm) and permanent magnetic elements, such as neodymium magnets and metallic meshes, were designed, manufactured and tested. The five types of filters were compared by measuring the decolorization of Congo Red dye inside bioreactors, the half-life of the filters and the amount of magnetic nanoparticle and enzyme lost during multiple cycles of operation. Filters containing laccase immobilized on magnetite (Laccase-magnetite), permanent magnets and metallic mesh presented the highest Congo Red decolorization (27%) and the largest half-life among all types of filters (seven cycles). The overall dye decolorization efficiencies were 5%, 13%, 17%, 23%, and 27% for the paper filter, paper filter with magnetite, paper filter with Laccase-magnetite, paper filter with Laccase-magnetite with magnets and paper filter with Laccase-magnetite with magnets and metallic mesh, respectively. Although the highest losses of magnetite occurred when using the filters containing magnets (57 mg), the use of permanent magnetic elements in the filters increased the half-life of the filter three-fold compared to the filters without enzymatic properties and two-fold compared to the filters with Laccase-magnetite. Results indicate that the novel use of permanent magnetic elements improved the nanoparticle retention in the filters and promoted the mass transfer between the dye and the biocatalyst to enhance wastewater treatment. [ABSTRACT FROM AUTHOR]

In many countries, soil contamination and lead exposure is a persistent human and environmental health issue, while in others, it is an emerging concern. Defining the extent of lead contamination and assessing human health risk allow for efficient prevention agendas. The different types of land uses delimit the exposure frequency and hence can influence the evaluation of possible threats. In this study, human health risk assessment is performed under different land use scenarios, after determining the concentration of lead in topsoil of a rehabilitated space. An analytical hybrid method was used to determine the concentrations of the heavy metal. Human health risk indicators, hazard quotient and cancer risk, were subsequently calculated and compared under such scenarios of varying population exposure by land use. Results indicate that an increasing exposure can set health risk indicators above the tolerable levels. Correctly defining the exposure frequency by land use is very important to determine the actual risk levels of a site. Local regulators should take this information into account before designing prevention plans, especially in localities where migration and urbanization are major development factors and since the land use of a public place could change over time and alter the exposure frequency to soil. [ABSTRACT FROM AUTHOR]

Surface modification in nanostructured mesoporous silica particles (MSNs) can significantly increase the uptake in myocardial cells. Herein, MSNs particles were synthesized and chemically functionalized to further assess their biocompatibility in rat myocardial cell line H9c2. The surface modification resulted in particles with an enhanced cellular internallization (3-fold increase) with respect to pristine particles. Apoptosis events were not evident at all, while necrosis incidence was significant only at a higher doses (> 500 μg/mL). In particular, the percentage of necrotic cells decrease in a statistically significant manner for the functionalized particles at lower doses than 100 μg/mL. This study concludes that the proposed surface functionalization of MSNs particles does not compromise their viability on H9c2 cells, and therefore they could potentially be used for biomedical purposes. Fourier-transform infrared, Raman, TGA/DSC, N 2 adsorption-desorption, and TEM techniques were used to characterize the as-prepared materials. Confocal microscopy and flow cytometry analyses were carried out to measure the histograms of cell complexity and the half maximal inhibitory concentration, respectively. Reactive oxygen species generation was accessed using assays with MitoSOX and Amplex Red fluoroprobes. [ABSTRACT FROM AUTHOR]

A multisyringe flow injection system with spectrophotometric detection is presented as a fast, robust and low-reagent consumption system for the determination of azinphos methyl (AzMe) in water samples. Determination is based on the Griess reaction. The analyte is hydrolyzed and the reaction product reacts with nitrite in acid medium to form the diazonium salt that reacts further with 1-naphtol reagent to produce an azo compound. The azo derivative is spectrophotometrically monitored at 485 nm. The influence of several chemical and flow variables has been investigated. Under the optimum analytical conditions, the linearity of the calibration curve for AzMe ranges from 1 to 32 μg mL−1. The detection limit is 0.17 µg mL−1, and recoveries between 95 to 109% have been obtained. The repeatability (RSD) is 0.8% for a 10 μg mL−1 solution, and the injection throughput is seven samples h−1. The system has been satisfactorily applied to the determination of AzMe in spiked river and dam water samples. The results were in agreement at the 95% confidence level with those obtained by HPLC. [ABSTRACT FROM AUTHOR]

The use of enzyme-based biosensors for the detection and quantification of analytes of interest such as contaminants of emerging concern, including over-the-counter medication, provides an attractive alternative compared to more established techniques. However, their direct application to real environmental matrices is still under investigation due to the various drawbacks in their implementation. Here, we report the development of bioelectrodes using laccase enzymes immobilized onto carbon paper electrodes modified with nanostructured molybdenum disulfide (MoS2). The laccase enzymes were two isoforms (LacI and LacII) produced and purified from the fungus Pycnoporus sanguineus CS43 that is native to Mexico. A commercial purified enzyme from the fungus Trametes versicolor (TvL) was also evaluated to compare their performance. The developed bioelectrodes were used in the biosensing of acetaminophen, a drug widely used to relieve fever and pain, and of which there is recent concern about its effect on the environment after its final disposal. The use of MoS2 as a transducer modifier was evaluated, and it was found that the best detection was achieved using a concentration of 1 mg/mL. Moreover, it was found that the laccase with the best biosensing efficiency was LacII, which achieved an LOD of 0.2 µM and a sensitivity of 0.108 µA/µM cm2 in the buffer matrix. Moreover, the performance of the bioelectrodes in a composite groundwater sample from Northeast Mexico was analyzed, achieving an LOD of 0.5 µM and a sensitivity of 0.015 µA/µM cm2. The LOD values found are among the lowest reported for biosensors based on the use of oxidoreductase enzymes, while the sensitivity is the highest currently reported. [ABSTRACT FROM AUTHOR]

In this study, the purification and characterization of two thermostable laccases produced by Pycnoporus sanguineus CS43 (LacI and LacII) were performed. Also, their biotechnological potential was assessed through the degradation of endocrine disrupting chemicals (EDCs). Laccases were purified by ultrafiltration, ion exchange (IEX) and hydrophobic interaction chromatography achieving specific activities close to 285 U mg −1 . The molecular weights of LacI and LacII, determined by SDS-electrophoresis, were 68 and 66 kDa, respectively. Both laccases showed high amino acid sequence similarity (91%) between them and high thermostability, at 50 and 60 °C (half-lives of 277.7 and 18 h for LacI, 35.8 and 2.25 h for LacII). The isoforms oxidized common laccase substrates such as 2,2′-azino-bis (3-ethylbenzthiazoline-6-sulfonate (ABTS), 2,6-dimethoxyphenol (DMP) and guaiacol at acidic pH conditions. ABTS was the most efficient substrate, showing high specificity constants of 74,816 and 36,746 mM −1 s −1 for Lac I and LacII, and Michaelis constants ( K m ) of 6.9 and 12.2 μM respectively at pH 3. Both purified laccases remained active at high concentrations of organic solvents (acetonitrile, ethanol and acetone), with an IC 50 (v/v) of >64%, 55% and 47% for LacI, and 33%, 52% and 31% for LacII, respectively. LacI and LacII were tested to degrade EDCs, nonylphenol and triclosan, with more than 95% removal after 8 h of treatment with 100 U/L at pH 5 as determined by means of HPLC. The high thermostability, unique Michaelis–Menten kinetic parameters, and organic solvent tolerance demonstrated for the isoforms produced by P. sanguineus CS43 render them promising candidates for industrial applications. LacI exerted a higher thermal and pH stability, tolerance against inhibitors and was a more efficient catalyst for ABTS and DMP than LacII. [ABSTRACT FROM AUTHOR]

Laser-induced breakdown spectroscopy (LIBS) is evaluated as a potential analytic technique for rapid screening and quality control of anti-diabetic tablets. This paper proposes a simple LIBS-based method for the quantitative analysis of two active pharmaceutical ingredients (APIs): metformin (Met) and glybenclamide (Gly). In order to quantify both APIs, chlorine (Cl) concentration was estimated by employing the Cl/Br optical emission ratio, where Br was introduced as internal standard. Calibration curves were prepared, achieving linearity higher than 99%. On the other hand, for comparison to the proposed method, an isocratic reversed-phase high-performance liquid chromatography (RP-HPLC) method was also developed for quantitative determination of the same analytes by ultraviolet (UV) detection. The chromatographic separation was achieved on a Phenomenex Hypersil C18, 250 mm × 4.6 mm, 5 μm column. The mobile phase was K2HPO4/H3PO4-CH3OH and flow rate was 1.0 mL min−1. The method is linear over a range of 10-60 μg mL−1for Gly and 5-30 μg mL−1for Met and the correlation coefficients were ≥0.99. Recoveries were found to be in the range of 95-101%. Furthermore, four different commercial brands of each active agent were evaluated by both proposed LIBS and chromatographic methods and results were compared with each other. The comparison was satisfactorily validated by analysis of variance (ANOVA). [ABSTRACT FROM AUTHOR]

In this work, the design, manufacture, and testing of three different magnetic microreactors based on torus geometries (i.e., one-loop, two-horizontal-loop, and two-vertical-loop) is explored to increase the enzyme-based transformation of dyes by laccase bio-nanocomposites, improve the particle suspension, and promote the interaction of reagents. The laccase enzyme was covalently immobilized on amino-terminated silanized magnetite nanoparticles (laccase-magnetite). The optimal configuration for the torus microreactor and the applied magnetic field was evaluated in silico with the aid of the CFD and particle tracing modules of Comsol Multiphysics®. Eriochrome Black T (EBt) dye was tested as a biotransformation model at three different concentrations, i.e., 5 mg/L, 10 mg/L, and 20 mg/L. Phenol oxidation/removal was evaluated on artificial wastewater and real wastewater. The optimal catalytic performance of the bionanocomposite was achieved in the range of pH 4 to 4.5. A parabolic movement on the particles along the microchannels was induced by the magnetic field, which led to breaking the stability of the laminar flow and improving the mixing processes. Based on the simulation and experiments conducted with the three geometries, the two-vertical-loop microreactor demonstrated a better performance mainly due to larger dead zones and a longer residence time. Additionally, the overall dye removal efficiencies for this microreactor and the laccase-magnetite bionanocomposite were 98.05%, 93.87%, and 92.74% for the three evaluated concentrations. The maximum phenol oxidation with the laccase-magnetite treatment at low concentration for the artificial wastewater was 79.89%, while its phenol removal efficiency for a large volume of real wastewater was 17.86%. Treatments with real wastewater were carried out with a larger volume, equivalent to 200 biotransformation (oxidation) operating cycles of those carried out with dyes or phenol. Taken together, our results indicate that the novel microreactors introduced here have the potential to process wastewaters rich in contaminant dyes in continuous mode with efficiencies that are attractive for a potential large-scale operation. In this regard, future work will focus on finding the requirements for scaling-up the processes and evaluating the involved environmental impact indexes, economic performance, and different device geometries and processing schemes. [ABSTRACT FROM AUTHOR]

The widespread presence of arsenic (As) and fluoride (F−) in groundwater poses substantial risks to human health on a global scale. These elements have been identified as the most prevalent geogenic contaminants in groundwater in northern Mexico. Consequently, this study aimed to evaluate the human health and ecological risks associated with the content of As and F− in the Meoqui-Delicias aquifer, which is in one of Mexico's most emblematic irrigation districts. Concentrations of As and F− were measured in 38 groundwater samples using ICP-MS and ion chromatography, respectively. Overall, these elements showed a similar trend across the aquifer, revealing a positive correlation between them and pH. The concentration of As and F− in the groundwater ranged from 5.3 μg/L to 303 μg/L and from 0.5 mg/L to 8.8 mg/L, respectively. Additionally, the levels of As and F− surpassed the established national standards for safe drinking water in 92% and 97% of samples, respectively. Given that groundwater is used for both agricultural purposes and human activities, this study also assessed the associated human health and ecological risks posed by these elements using Monte Carlo simulation and Species Sensitivity Distribution. The findings disclosed a significant noncarcinogenic health risk associated with exposure to As and F−, as well as an unacceptable carcinogenic health risk to As through water consumption for both adults and children. Furthermore, a high ecological risk to aquatic species was identified for F− and high to medium risks for As in the sampling sites. Therefore, the findings in this study provide valuable information for Mexican authorities and international organizations (e.g., WHO) about the adverse effects that any exposure without treatment to groundwater from this region represents for human health. [Display omitted] • As and F− in groundwater exceeded Mexican drinking standards in 92% and 97% of cases, respectively. • Probabilistic model suggests an 82% chance for adults, 95% for children to exceed safe As levels. • A high ecological risk to aquatic species was identified for F- and high to medium risks for As. • Excessive As and F- in drinking water linked to cancer, cognitive issues, posing widespread health risks. [ABSTRACT FROM AUTHOR]

Recent evidence has shown that nanoparticles that have been used to improve or create new functional properties for common products may pose potential risks to human health. Silicon dioxide (SiO2) has emerged as a promising therapy vector for the heart. However, its potential toxicity and mechanisms of damage remain poorly understood. This study provides the first exploration of SiO2-induced toxicity in cultured cardiomyocytes exposed to 7- or 670-nm SiO2 particles. We evaluated the mechanism of cell death in isolated adult cardiomyocytes exposed to 24-h incubation. The SiO2 cell membrane association and internalization were analyzed. SiO2 showed a dose-dependent cytotoxic effect with a half-maximal inhibitory concentration for the 7 nm (99.5 ± 12.4 μg/ml) and 670 nm (>1,500 μg/ml) particles, which indicates size-dependent toxicity. We evaluated cardiomyocyte shortening and intracellular Ca2+ handling, which showed impaired contractility and intracellular Ca2+ transient amplitude during -adrenergic stimulation in SiO2 treatment. The time to 50% Ca2+ decay increased 39%, and the Ca2+ spark frequency and amplitude decreased by 35 and 21%, respectively, which suggest a reduction in sarcoplasmic reticulum Ca2+-ATPase (SERCA) activity. Moreover, SiO2 treatment depolarized the mitochondrial membrane potential and decreased ATP production by 55%. Notable glutathione depletion and H2O2 generation were also observed. These data indicate that SiO2 increases oxidative stress, which leads to mitochondrial dysfunction and low energy status; these underlie reduced SERCA activity, shortened Ca2+ release, and reduced cell shortening. This mechanism of SiO2 cardiotoxicity potentially plays an important role in the pathophysiology mechanism of heart failure, arrhythmias, and sudden death. [ABSTRACT FROM AUTHOR]

Given the well-known physical properties of graphene oxide (GO), numerous applications for this novel nanomaterial have been recently envisioned to improve the performance of biomedical devices. However, the toxicological assessment of GO, which strongly depends on the used material and the studied cell line, is a fundamental task that needs to be performed prior to its use in biomedical applications. Therefore, the toxicological characterization of GO is still ongoing. This study contributes to this, aiming to synthesize and characterize GO particles and thus investigate their toxic effects in myocardial cells. Herein, GO particles were produced from graphite using the Tour method and subsequent mild reduction was carried out to obtain low-reduced GO (LRGO) particles. A qualitative analysis of the viability, cellular uptake, and internalization of particles was carried out using GO (~ 54% content of oxygen) and LRGO (~ 37% content of oxygen) and graphite. GO and LRGO reduce the viability of cardiac cells at IC 50 of 652.1 ± 1.2 and 129.4 ± 1.2 μg/mL, respectively. This shows that LRGO particles produce a five-fold increase in cytotoxicity when compared to GO. The cell uptake pattern of GO and LRGO particles demonstrated that cardiac cells retain a similar complexity to control cells. Morphological alterations examined with electron microscopy showed that internalization by GO and LRGO-treated cells (100 μg/mL) occurred affecting the cell structure. These results suggest that the viability of H9c2 cells can be associated with the surface chemistry of GO and LRGO, as defined by the amount of oxygen functionalities, the number of graphitic domains, and the size of particles. High angle annular dark-field scanning transmission electron microscopy, dynamic light-scattering, Fourier-transform infrared, Raman, and X-ray photoelectron spectroscopies were used to characterize the as-prepared materials. [ABSTRACT FROM AUTHOR]

A Surface Plasmon Resonance (SPR) biosensor based on an inhibition immunoassay was developed for the detection of diclofenac (DCF) in aqueous solution. Due to the small size of DCF, an hapten-protein conjugate was produced by coupling DCF to bovine serum albumin (BSA). DCF-BSA conjugate formation was confirmed via MALDI-TOF mass spectrometry. The resulting conjugate was immobilized onto the surface of a sensor fabricated via e-beam deposition of a 2 nm chromium adhesion layer followed by a 50 nm gold layer onto precleaned BK7 glass slides. Immobilization onto the nano thin gold surface was accomplished by covalent amide linkage through a self-assembled monolayer. Samples were composed of a mixture of antibody at a fixed concentration and DCF at different known concentrations in deionized water, causing the inhibition of anti -DCF on the sensor. The DCF-BSA was obtained with a ratio of 3 DCF molecules per BSA. A calibration curve was performed using concentrations between 2 and 32 μg L−1. The curve was fitted using the Boltzmann equation, reaching a limit of detection (LOD) of 3.15 μg L−1 and limit of quantification (LOQ) of 10.52 μg L−1, the inter-day precision was calculated and an RSD value of 1.96% was obtained; and analysis time of 10 min. The developed biosensor is a preliminary approach to the detection of DCF in environmental water samples, and the first SPR biosensor developed for DCF detection using a hapten-protein conjugate. [Display omitted] • An SPR immunosensor was developed to detect diclofenac in water samples. • The configuration of the immunosensor involves the conjugation of diclofenac and BSA as a carrier protein. • This is the first SPR immunosensor for diclofenac that uses the target analyte conjugated to a protein. • The obtained results are comparable with the only other work published for diclofenac detection using SPR. • The development of this kind of biosensors could help to star regulating the discharge of diclofenac in water. [ABSTRACT FROM AUTHOR]

Surface-Enhanced Raman Spectroscopy (SERS) is a powerful surface-sensitive technique to study the vibrational properties of analytes at very low levels of concentration. In particular, detection of bioactive molecules, specifically antioxidants, is an area of interest to gain insights into the reproducible and quantitative SERS-determination. In this study, SERS measurements were systematically evaluated for ferulic acid, p -coumaric acid, caffeic acid and sinapic acid. The study objective in this research was to: 1) prepare and characterize SERS-active silver colloids; 2) cluster the as-obtained colloids through Principal Component Analysis on the basis of concentration and nanoparticle size; and 3) develop a highly sensitive SERS-based method for phenolic antioxidant detection. The reliability of the proposed method was demonstrated through detection of the phenolic antioxidants evaluated at low levels of concentration. In particular, sinapic acid was evaluated for the first time, with a limit of detection of 2.5 × 10 −9 M. [ABSTRACT FROM AUTHOR]

Intensive use of organophosphorus pesticides (OPs) leads to their accumulation in most compartments of the environment, creating an issue of international concern that demands development and implementation of analytical methods for the assessment of environment quality. Official protocols require the use of sophisticated instruments, such as high performance liquid chromatography-mass spectrometry or gas chromatography/mass spectrometry, for the accurate and sensitive determination of OPs; however, methods based on these techniques are inconvenient for routine analysis of large numbers of samples or on-site analysis. Therefore, simple and fast alternative methods for the determination of OPs are needed. In this work, a colorimetric assay based on decrease in catalytic activity of chloroperoxidase (CPO) enzyme has been developed for the detection and quantification of OPs. Decrease in standard catalytic activity of CPO (halogenation of thionin acetate) was due to competition by OPs for the enzyme's active site, which affected CPO kinetic constants. Consequently, a correlation was observed between concentration of OPs and decrease in CPO catalytic activity, enabling indirect determination of OPs in water samples. The proposed method demonstrated mean recoveries between 92.3% and 106.5%, with a measuring time of 20 s per sample. The enzymatic analytical method was applied to groundwater samples. Performance of the developed assay is comparable to that of commercial assay kits based on the enzyme acetylcholinesterase, but has a shorter analysis time and does not require a preoxidation step. Therefore, this approach constitutes a sensitive, fast, and high-throughput method for OPs screening in aquatic environments. [ABSTRACT FROM AUTHOR]

The present study reports the localization and interaction of thioglycolic acid (TGA) capped CdTe quantum dots (TGA@CdTe QDs) within the extracellular matrix (ECM) of Haematococcus pluvialis (Chlorophyceae) microalgae (HPM) after an incubation period of 5 min. Changes in the Raman spectrum of HPM induced by the adsorption of the TGA@CdTe QDs are successfully found by using naked gold anisotropic structures as nano-sensors for surface-enhanced Raman scattering (SERS effect). Raman spectroscopy results show that TGA@CdTe QDs interact with the biomolecules present in the ECM. Sample preparation and characterization by complementary techniques such as confocal and electron microscopy are also used to confirm the presence and localization of the nanoparticles in the algae. This research shows new evidence on early accumulation of QDs in plant cells and would further improve our understanding about their environmental impact. [ABSTRACT FROM AUTHOR]

In this work, the biocatalytic ability of laccases from filtered culture supernatant of Pycnoporus sanguineus was evaluated without mediators and under mild reaction conditions. This 100 U L −1 laccase cocktail removed 50% Diclofenac, 97% β-Naphthol and 71% 2,4 Dichlorophenol within 8 h of reaction and 78% for 5,7-Diiodo-8-hydroxyquinoline within 3.5 h; at initial concentrations of 10 mg L −1 and at 25 °C. Furthermore, this enzyme cocktail also removed in excess of 53% all tested compounds in a real groundwater sample from northwestern Mexico. In comparison with purified laccases, the use of cocktail offers operational advantages since additional purification steps can be avoided. [ABSTRACT FROM AUTHOR]

The marked trend and consumers growing interest in natural and healthy products have forced researches and industry to develop novel products with functional ingredients. Microalgae have been recognized as source of functional ingredients with positive health effects since these microorganisms produce polyunsaturated fatty acids, polysaccharides, natural pigments, essential minerals, vitamins, enzymes and bioactive peptides. For this reason, the manuscript reviews two of the main high-value metabolites which can be obtained from microalgae: pigments and essential lipids. Therefore, the extraction and purification methods for polyunsaturated fatty acids, astaxanthin, phycoerythrin and phycocyanin are described. Also, the effect that environmental growth conditions have in the production of these metabolites is described. This review summarizes the existing methods to extract and purify such metabolites in order to develop a feasible and sustainable algae industry. [ABSTRACT FROM AUTHOR]

Mexico's government has introduced a Law on Climate Change that is unique worldwide; it establishes targets for greenhouse gases reductions at the same level of developed countries despite being an emerging country. This reform represents a crucial challenge for the electrical and transport sectors largely dependent on fossil energy since Mexico is the ninth-largest oil producer in the world. Local industry and academic sectors are called to lead the introduction of renewable energy sources, and particularly to enhance the share of energy from biomass in the local energy basket. Thus, this paper outlines the baseline on regulatory, energy, and carbon markets, and the scientific capacity to increase bioenergy utilization in Mexico. Furthermore, it opens a discussion about the steps forward with regard to sustainability and research needs, emphasizing some priorities and principles to develop a bioenergy system environmentally compatible in this country. © 2014 The Authors. Biofuels, Bioproducts, Biorefining published by Society of Chemical Industry and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A literature review was carried out to analyze the current status of microplastic research in Latin America and the Caribbean (LAC). Specifically, this work focused on publications pertaining to (1) occurrence and distribution of microplastics in the environment, including water, sediments, and soil and (2) the environmental impact of MPs, particularly their presence and effects on aquatic and terrestrial organisms. The review included peer-reviewed articles from Scopus, Science Direct, Web of Science, Google Scholar and two iberoamerican open access databases (Redalyc and SciELO). It was found that LAC has only contributed to 5% of the global scientific output on microplastics, and overall the highest contributor within the region was Brazil (52%), followed by Chile (16%) and Mexico (13%). An additional section analyzing the barriers to conducting microplastic research in LAC and their exacerbation by the current COVID-19 pandemic was included to provide additional context behind the relatively low scientific production and improve recommendations encouraging research in this region. • Most of the studies in LAC were focused on occurrence and effects of MPs in biota. • Morphological and behavioral changes were observed in LAC organisms exposed to MPs. • In coastal areas of LAC, PP and PE were the most frequently detected type of MP. • Studies from the LAC coastlines showed the danger of pollutants adsorbed on MPs. [ABSTRACT FROM AUTHOR]

Highly reproducible quaternary CdZnSeS quantum dots (QDs) have been synthesized by the hot injection method using the reactivity difference between the molar ratio of Cd/Zn and Se/S precursors. The obtained QDs exhibit characteristics of quaternary CdZnSeS QDs. The morphology of the CdZnSeS QDs was observed in the TEM. The average size of the QDs was in the range between 5.5 and 7.5 nm for reaction times between 5 and 60 min, respectively. High photoluminescence emission, in the range from 460 to 680 nm, was obtained varying the Cd to Zn and the Se to S concentrations. Varying the concentration of Zn and S, emissions of blue, green, yellow, or red, were obtained. Additionally, the CdZnSeS QDs were used as the emissive layer in light-emitting diodes (LEDs) prepared with the configuration ITO/PEDOT:PSS/PVK/CdZnSeS/Al. These devices emitted a bright single color of blue, green, or red. • Highly reproducible quaternary CdZnSeS quantum dots (QDs) have been synthesized. • CdZnSeS QDs were used as the emissive layer in light-emitting diodes (LEDs). • The devices emitted a bright single color of blue, green, or red. [ABSTRACT FROM AUTHOR]

• A novel methodology using an effective refractive index to characterize the surface plasmon resonance angle. • Optical technique for detection of bovine serum albumin and carbamazepine • Possibility to infer changes onto the surface of gold films using microfluidic systems. Surface plasmon resonance was used for the detection of different kinds of organic molecules, which was achieved employing a Kretschmann configuration. A simple theoretical model based on effective medium theory was used for estimation of the SPR angle. The employed model considers an effective refractive index, which has some advantages in comparison to other effective medium theories. This model depends on the surface coverage, size of the sample and also considers the scattering by molecules deposited on the surface of the thin film. Using an effective refractive index as a tool to predict the behavior of the SPR signal offers a significant advantage for the development of new biosensors, providing a deeper physical insight on the behavior of such phenomena, since inferring the behavior of SPR signals is of great importance for chemical analysis and bio-sensing. Therefore, in this work, an effective medium model was compared with experimental SPR measurements as a function of angle incidence of different molecules deposited onto thin films, specifically Bovine Serum Albumin (BSA) and carbamazepine attached to BSA, in order to validate the theoretical model. Evaluation of the proposed model for SPR signal was in good agreement with the experimental results. Statistical tests were obtained, with a 99% of correlation between the experimental data and the theoretical predictions around the resonance. [ABSTRACT FROM AUTHOR]

Over the past decades, groundwater quality has deteriorated worldwide by nitrate pollution due to the intensive use of fertilizers in agriculture, release of untreated urban sewage and industrial wastewater, and atmospheric deposition. Likewise, groundwater is increasingly polluted by sulfate due to the release of domestic, municipal and industrial wastewaters, as well as through geothermal processes, seawater intrusion, atmospheric deposition, mineral dissolution, and acid rain. The urbanized and industrialized Monterrey valley has a long record of elevated nitrate and sulfate concentrations in groundwater with multiple potential pollution sources. This study aimed to track different sources and transformation processes of nitrate and sulfate pollution in Monterrey using a suite of chemical and isotopic tracers (δ2H–H 2 O, δ18O–H 2 O, δ15N–NO 3 , δ18O–NO 3 δ34S–SO 4 , δ18O–SO 4) combined with a probability isotope mixing model. Soil nitrogen and sewage were found to be the most important nitrate sources, while atmospheric deposition, marine evaporites and sewage were the most prominent sulfate sources. However, the concentrations of nitrate and sulfate were controlled by denitrification and sulfate reduction processes in the transition and discharge zones. The approach followed in this study is useful for establishing effective pollution management strategies in contaminated aquifers. Image 1 • Groundwater nitrate and sulfate sources and transformation were investigated. • Water chemistry, stable isotopes, and a Bayesian mixing model were combined. • Soil nitrogen and sewage were the most important nitrate sources. • Atmospheric deposition, marine evaporites and sewage were the main sulfate sources. • Contamination was controlled by denitrification and sulfate reduction processes. [ABSTRACT FROM AUTHOR]

Polymeric microcapsules with the fungal laccase from Pycnoporus sanguineus CS43 may represent an attractive avenue for the removal or degradation of dyes from wastewaters. Microcapsules of alginate/chitosan (9.23 ± 0.12 µm) and poly(styrenesulfonate) (PSS) (9.25 ± 0.35 µm) were synthesized and subsequently tested for catalytic activity in the decolorization of the diazo dye Congo Red. Successful encapsulation into the materials was verified via confocal microscopy of labeled enzyme molecules. Laccase activity was measured as a function of time and the initial reaction rates were recovered for each preparation, showing up to sevenfold increase with respect to free laccase. The ability of substrates to diffuse through the pores of the microcapsules was evaluated with the aid of fluorescent dyes and confocal microscopy. pH and thermal stability were also measured for encapsulates, showing catalytic activity for pH values as low as 4 and temperatures of about 80 °C. Scanning electron microscope (SEM) analyses demonstrated the ability of PSS capsules to avoid accumulation of byproducts and, therefore, superior catalytic performance. This was corroborated by the direct observation of substrates diffusing in and out of the materials. Compared with our PSS preparation, alginate/chitosan microcapsules studied by others degrade 2.6 times more dye, albeit with a 135-fold increase in units of enzyme per mg of dye. Similarly, poly(vinyl) alcohol microcapsules from degrade 1.7 times more dye, despite an eightfold increase in units of enzyme per mg of dye. This could be potentially beneficial from the economic viewpoint as a significantly lower amount of enzyme might be needed for the same decolorization level achieved with similar encapsulated systems. [ABSTRACT FROM AUTHOR]

Removal of azo and diazo dye content from textile industry wastewaters is crucial due to their environmental impact. Here, we report on the use of the fungal laccase from Pycnoporus sanguineus CS43 immobilized on silica nanoparticles and entrapped in textile-based filters for the degradation of Congo Red. Laccase immobilization and synthesis of the nanocomposites were carried out by two different methods, one in the presence of acetone and the second using water as solvent. This led to a change in the hydrophobicity of the obtained biofilters. Successful preparation of the nanocomposites was confirmed via FTIR spectroscopy. Changes in the secondary structure of the enzyme were inspected through the second derivative of the FTIR spectra. Six different types of filter were fabricated and tested in a continuous flow bioreactor in terms of their decolorization capabilities of Congo Red. The results indicate removal efficiencies that approached 40% for enzymes immobilized on the more hydrophobic supports. Backscattered electron (BSE) images of the different filters were obtained before and after the decolorization process. Percentage of decolorization and activity loss were determined as a function of time until a plateau in decolorization activity was reached. Experimental data was used to recreate the decolorization process in COMSOL Multiphysics® (Stockholm, Sweden). These simulations were used to determine the proper combination of parameters to maximize decolorization. Our findings suggest that the treatment of textile-based filters with immobilized laccase in conjunction with hydrophobic nanocomposites provides a suitable avenue to achieve more efficient laccase dye decolorization (39%) than that obtained with similar filters treated only with free laccase (8%). Filters treated with silica-based nanocomposites and immobilized laccases showed an increase in their decolorization capability, probably due to changes in their wetting phenomena. [ABSTRACT FROM AUTHOR]

• Novel laccase biosensors were applied in dopamine detection in synthetic urine. • Two nanostructured MoS 2 materials were assessed for signal amplification. • Laccase from P. sanguineus used for the first time in an electrochemical biosensor. • Laccase based biosensors presented high sensitivity and low LOD (10 nM) for dopamine. A novel laccase-based amperometric biosensor was developed through the modification of carbon paper electrodes with layered two-dimensional molybdenum disulfide (MoS 2) presented in two different morphologies, flowers (MoS 2 -F) and ribbons (MoS 2 -R). Two laccase isoforms from Pycnoporus sanguineus CS43 fungi (LacI and LacII) were evaluated for the first time as a biological recognition element, and their performance was compared with commercial laccase from Trametes versicolor (TvL). The best results were observed with the MoS 2 -R morphology at a concentration of 2 mg/mL Biosensors modified with MoS 2 -R and with the three enzymes, showed two linear ranges of detection, from 0.1 to 0.5 µM and from 1 to 5 µM. Biosensors modified with LacII exhibited a high sensitivity of 340.3 nA/µM; and low limit of detection (LOD) of 10 nM, which are the best values reported in the literature for dopamine detection by laccase based biosensor. Optimized electrodes modified with enzymes LacII and TvL were tested in a synthetic urine sample in order to evaluate their practical effectiveness, resulting in LOD of 0.67 and 2.67 µM respectively, which are below the average concentrations of dopamine normally found in real urine samples (around 2 µM). Image, graphical abstract [ABSTRACT FROM AUTHOR]

The development of microfluidics-based systems in the recent years has provided a rapid and controlled method for the generation of monodisperse microencapsulates for multiple applications. Here, we explore the design, manufacture and characterization of a low-cost microsystem for the encapsulation of the fungal laccase from Pycnoporus sanguineus CS43 in alginate microcapsules. Multiphysics simulations were used to overview the fluid behavior within the device and estimate the resulting capsule size. Polymethylmethacrylate (PMMA) sheets were used for final microsystem manufacture. Different flow rates of the continuous (Qc) and discrete (Qd) phases in the ranges of 83–293 mL/h and 1–5 mL/h, respectively, were evaluated for microcapsule fabrication. Universal Serial Bus (USB) microscope and image analysis was used to measure the final particle size. Laccase encapsulation was evaluated using spectrophotometry and with the aid of fluorescent dyes and confocal microscopy. Results showed microcapsule size was in the range of 203.13–716.00 μm and Qc was found as the dominant parameter to control capsule size. There was an effective enzyme encapsulation of 65.94% with respect to the initial laccase solution. [ABSTRACT FROM AUTHOR]