AuPt Bipyramid Nanoframes as Multifunctional Platforms for In Situ Monitoring of the Reduction of Nitrobenzene and Enhanced Electrocatalytic Methanol Oxidation

Multifunctional metal nanostructures with a hollow feature, especially for nanoframes, are highly attractive owing to their high surface-to-volume ratios. However, pre-grown metal nanocrystals are always involved during the preparation procedure, and a synthetic strategy without the use of a pre-grown template is still a challenge. In this article, a template-free strategy is reported for the preparation of novel AuPt alloy nanoframes through simply mixing HAuCl₄ and H₂PtCl₆ under mild conditions. The alloy nanostructures show a bipyramid-frame hollow architecture with the existence of only the ten ridges and absence of their side faces. This is the first report of bipyramid-like nanoframes and a template-free method under mild conditions. This configuration merges the plasmonic features of Au and highly active catalytic sites of Pt in a single nanostructure, making it an ideal multifunctional platform for catalyzing and monitoring the catalytic reaction in real time. The superior catalytic activity is demonstrated by using the reduction of nitrobenzene to the corresponding aminobenzene as a model reaction. More importantly, the AuPt nanoframes can track the reduction process on the basis of the SERS signals of the reactants, intermediates, and products, which helps to reveal the reaction mechanism. In addition, the AuPt nanoframes show much higher electrocatalytic properties toward the methanol oxidation reaction than commercial Pt/C electrocatalysts.     

Multiplexed therapeutic drug monitoring of antipsychotics in dried plasma spots by LC‐MS/MS

In this work, a convenient method for the therapeutic monitoring of seven common antipsychotic drugs in “dried plasma spot” samples has been developed. It is based on the liquid chromatography tandem mass spectrometry technique, operating in multiple reaction monitoring mode, and a straightforward procedure for the simultaneous extraction of all antipsychotics in a single step, with high extraction yield. The method was fully validated with proper accuracy, precision, selectivity and sensitivity, for all the drugs. Limits of quantification were 0.12, 1.09, 1.46, 1.47, 5.70, 1.32, 1.33 µg/L for haloperidol, aripiprazole, olanzapine, quetiapine, clozapine, risperidone, and paliperidone, respectively. Accuracy, intra‐ and interday precision values were <10% for all drugs at all concentration levels examined. The method was tested in the analysis of 30 plasma samples from real patients for each drug. The proposed analytical approach, by combining practical and logistical advantages of microsampling with liquid chromatography tandem mass spectrometry analytical performance, could offer an ideal strategy for accurate and timely therapeutic drug monitoring of antipsychotic drugs in most clinical settings, even in remote centers and/or in out‐patient settings, bringing so many potential improvements in psychiatric patient care.     

Capillary zone electrophoresis of lipoarabinomannan by multi-layered concentration

The present article describes a capillary zone electrophoresis method which relies on a multilayered water-alkali solvent stacking with online ionization to enhance detection of mannose, arabinose, and their oligosaccharides, which are used as the migration profile standards but are also the distinctive structural components of lipoarabinomannan. Lipoarabinomannan is detected in patients having tuberculosis. The capillary electrophoresis method with ionization of the whole saccharides without degradation in alkaline solution inside the capillary is based on the structural deprotonation of the molecules under ultrahigh pH conditions. The validation of the capillary electrophoresis parameters revealed that the 15-fold electrolyte–water-injection plug allowed detection of one-third lower concentrations than detected without online concentration. For the first time, the better detectability was seen especially for highly polymerized, but otherwise poorly ionized, arabinooctaose. The applicability of the method for detecting whole large biological saccharide complexes was confirmed by the glycolipid lipoarabinomannan. For the first time also, the migration of the indestructible lipoarabinomannan was detected together with oligosaccharides used representing the capping units, namely mannose, mannobiose, and mannotriose. The myo-inositol-phosphate-lipid unit was seen to migrate separately from the arabinomannan, since it was hydrolyzed from one lipoarabinomannan product under alkaline conditions in capillary electrophoresis.     

Electrochemical detection of nitrate,nitrite and ammonium for on-site water quality monitoring

This review examines the most recent electrochemical developments for nitrate, nitrite and ammonium detection for on-site water monitoring. There remains a high demand for effective field-based detection of the dissolved inorganic nitrogen (DIN) analytes to aid in mitigating nitrogen loading. Electrochemical approaches show increasing potential to fill this role as advancements in nanotechnology continually improve analytical performance and on-site applicability. However, translating these improvements into the field still faces the resonating challenges of reaching analytical proficiency (selectivity, sensitivity, robustness, stability), practical end-user functionality, minimal matrix interferences and cost effectiveness. Herein, we elaborate on these challenges via a critical evaluation of current studies and examine how realistic the prospects of on-site nitrate, nitrite and ammonium are. We also present recommendations in addressing these gaps to conclude the review.     

One-pot reactions of nitroenamines with anilines and ethyl glyoxylate

In a simple, one-pot, catalyst-free procedure starting from heterocyclic nitroenamines, substituted anilines and ethyl glyoxylate new ethyl 2-arylamino-3-nitro-propionates were prepared in good to excellent yields. Depending on the substituent pattern of the anilines applied, two routes for the one-pot reaction are suggested. Additionally, it was demonstrated that these multifunctional compounds of aza-Morita–Baylis–Hillman type were also formed in two-step protocols either from imines and nitroenamines or from the adducts of nitroenamines and ethyl glyoxylate with anilines.     

Sustainable alternative in environmental monitoring using carbon nanoparticles as optical probes

Environmental monitoring is getting more important nowadays due to the greater stress faced by the natural environment in the era of urbanisation and industrialisation. To accomplish the task, rapid and reliable analytical probes are essentially needed to perform the monitoring at real time basis with high sensitivity and accuracy. In view of this, analytical probes developed using carbon nanoparticles are one of the latest alternatives that are proven with capability to detect various analytes of the environment. Carbon nanoparticles portray good fluorescence property that enables the integration onto optical sensing transducers. Further engineering via surface functionalization can be performed in the interest to improve the selectivity and sensitivity of the probes. There are several advantages of using carbon nanoparticles and the most significant benefit is the sustainability prospect as compared to other groups of fluorophores. Carbon nanoparticles can be synthesised with greener approach via simple pyrolysis or hydrolysis processes that involve minimum use of toxic or harmful starting precursors, besides able to tap on using renewable resources such as carbon rich agricultural wastes. The synthesis is often performed under mild condition and produces less or no side chemical products. Carbon nanoparticles by nature show low toxicity effect to the environment. This review focuses specifically of the sustainable significances, advantages and achievements in adopting carbon nanoparticles as an alternative for environmental monitoring.     

Monitoring the manufacturing process of glass fiber reinforced composites with carbon nanotube buckypaper sensor

Buckypapers are free-standing porous mats of entangled CNT ropes cohesively bounded by van der waals interactions, and can be used to monitor the manufacturing process of glass fiber reinforced composite. In this paper, the buckypaper (BP) was fabricated with monodispersion of multi-wall carbon nanotubes via spray-vacuum filtration, and its morphology and pore size distribution were characterized by scanning electron microscope and nitrogen adsorption/desorption. The resistance of the BP sensor was obtained using a four-point probe method, and the resistance changes could be related to phase changes of the resin matrix,. Experimental results show that the BP sensor embedded in the glass/epoxy composite laminates has indicated a relative resistance change from −2.9% to 226.5% during the manufacturing process. In addition, the temperature sensitivity of a pristine BP sensor and a BP sensor embedded in composite were also characterized. The results demonstrate that the effect of resin phase changes on the resistance changes of a BP sensor is greater than that of the temperature during composite manufacturing.     

Real-time assessment of carbon nanotube alignment in a polymer matrix under an applied electric field via polarized Raman spectroscopy

A technique has been developed utilizing polarized Raman spectroscopy to measure alignment of carbon nanotubes in situ in a polymer matrix under an applied electric field. Previous studies of alignment have been restricted to optically transparent solvents or polymerized specimens that prevent accurate analyses of alignment dynamics in polymers. The effects of electric field strength on the degree of alignment and the time to achieve an aligned state are discussed. The use of in situ, real-time polarized Raman spectroscopy provides a non-invasive technique for assessing carbon nanotube alignment, which can assist in determining processing conditions to improve the mechanical and electrical properties of aligned nanocomposites.     

Quantitative determination of isoquinoline alkaloids and chlorogenic acid in Berberis species using ultra high performance liquid chromatography with hybrid triple quadrupole linear ion trap mass spectrometry

Berberis species are well known and used extensively as medicinal plants in traditional medicine. They have many medicinal values attributable to the presence of alkaloids having different pharmacological activities. In this study, a method was developed and validated as per international conference on harmonization guidelines using ultra high performance liquid chromatography with hybrid triple quadrupole‐linear ion trap mass spectrometry operated in the multiple reaction monitoring mode for nine bioactive compounds, including protoberberine alkaloids, aporphine alkaloids and chlorogenic acid. This method was applied in different plant parts of eight Berberis species to determine variations in content of nine bioactive compounds. The separation was achieved on an ACQUITY UPLC CSH? C₁₈ column using a gradient mobile phase at flow rate 0.3 mL/min. Calibration curves for all the nine analytes provided optimum linear detector response (with R² ≥0.9989) over the concentration range of 0.5–1000 ng/mL. The precision and accuracy were within RSDs ≤2.4 and ≤2.3%, respectively. The results indicated significant variation in the total contents of the nine compounds in Berberis species.     

Computational analysis for the determination of deleterious nsSNPs in human MTHFD1 gene

Single nucleotide polymorphisms (SNPs) are the most common genetic polymorphisms and play a major role in many inherited diseases. Methylenetetrahydrofolate dehydrogenase 1 (MTHFD1) is one of the enzymes involved in folate metabolism. In the present study, the functional and structural consequences of nsSNPs of human MTHFD1 gene was analyzed using various computational tools like SIFT, PolyPhen2, PANTHER, PROVEAN, SNAP2, nsSNPAnalyzer, PhD-SNP, SNPs&GO, I-Mutant, MuPro, ConSurf, InterPro, NCBI Conserved Domain Search tool, ModPred, SPARKS-X, RAMPAGE, FT Site and PyMol. Out of 327 nsSNPs form human MTHFD1 gene, total 45 SNPs were predicted as functionally most significant SNPs, among which 17 were highly conserved and functional, 17 were highly conserved and structural residues. Among 45 most significant SNPs, 15 were predicted to be involved in post translational modifications. The p.Gly165Arg may interfere in homodimer interface formation. The p.Asn439Lys and p.Asp445Asn may interfere in binding interactions of MTHFD1 protein with cesium cation and potassium. The two SNPs (p.Asp562Gly and p.Gly637Cys) might interfere in interactions of MTHFD1 with ligand.