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Simultaneous detection of multiple amino acids (AAs) instead of individual AAs is inherently worthwhile for improving diagnostic accuracy in clinical applications. Here, a facile and reliable colorimetric microfluidic paper-based analytical device (μPAD) using carbon dots doped with transition metals (Cr 3+ , Mn 2+ , Fe 3+ , Co 2+ , Ni 2+ , Cu 2+ , and Zn 2+ ) has been provided to detect and discriminate 20 natural amino acids. To make the colourless metal-doped carbon dots suitable for colorimetric assays, they were mixed with ninhydrin to form a charge transfer complex. This optical tongue system, which was constructed by dropping mixtures of ninhydrin with a series of metal-doped carbon dots on a paper substrate in an array format, represented obvious but different colorimetric signatures for every examined amino acid. Since bovine serum albumin was used as a chiral selector reagent for synthesizing the CDs, the sensor device represented excellent selectivity to identify enantiomeric species of AAs. This is the first optical array device that can simultaneously discriminate AAs and several of their enantiomers. We employed various statistical and chemometric methods to analyze the digital data library collected by Image J software, including principal component analysis (PCA), linear discriminant analysis (LDA), and hierarchical cluster analysis (HCA). Twenty AAs could be well distinguished at various concentrations (10.00, 5.00, 2.50, and 1.25 mM). The colorimetric patterns were highly repeatable and were characteristic of individual AAs. Besides qualitative analysis, the designed μPAD-based optical tongue represented quantitative analysis ability, e.g. , for lysine in the concentration ranges of 0.005-20.0 mM with a detection limit of 1.0 × 10 -6 M and for arginine in the concentration range of 0.12-20.00 mM with a detection limit of 80.0 × 10 -6 M. In addition, the binary, ternary, and quaternary mixtures of AAs could also be well recognized with this sensor.

Amino acids are closely related to human health, and their rapid determination is important for the rapid diagnosis, timely treatment, and assessment of serious diseases. In this work, we propose a novel paper-based sample-processing device combined with isotope-dilution MS for the fast analysis of 11 amino acids from blood samples. By using an isoelectric focusing electrokinetic separation method, without the aid of carrier ampholytes and the addition of inhibitors, this approach uses only the characteristic of the isoelectric point of the target amino acids to achieve separation and purification from other coexisting components in the medium; it can meet the requirements for mass spectrometry detection. Driven by a DC voltage, a stable and sharp pH gradient (pH 3-10.5 over 5 mm) can be established in a glass-fiber paper-based fluidic channel with a MS-friendly electrolyte. Amphoteric species can be well separated from the complex blood matrix and concentrated into a narrow band in the channel within 2 min, which is 20 times faster than a commercial kit method. The method can be applied to both liquid and dry spot samples, and the cleaned sample band can be simply dissolved for direct IDMS detection in ESI MRM mode. This method is a promising strategy for the rapid MS-based detection of amino acids from serum without pre-separation via liquid chromatography.

In this paper, a novel fluorescent probe, TPA-PAT, with continuous recognition based on triphenylamine was designed, synthesized, and characterized by NMR, IR, and fluorescence spectrophotometry techniques. The research results showed that the probe could specifically recognize Cu2+ in DMSO/H2O (99:1, v/v) with a detection limit as low as 0.40 mM and a coordination ratio of 1: 2. On this basis, it was found that its complex TPA-PAT-Cu2+ could achieve a continuous progressive recognition of the anion S2- and amino acids GSH, L-His, and L-Gly, while simultaneously showing high sensitivity for them with low detection limits of 25.7, 18.9, 21.7, and 45.9 nM, respectively. The probe had good reversibility and could be recycled. In addition, the probe TPA-PAT could simultaneously recognize Cu2+ and Hg2+ in acetone/H2O (99:1, v/v) with detection limits of 0.16 and 0.20 mM, respectively, while their coordination ratios were 1: 2. Similarly, its complex TPA-PAT-Hg2+ was able to continuously recognize the amino acids Cys and GSH with detection limits of 0.34 and 0.29 mM, respectively. It was also found that the probe and its complexes were able to be prepared for convenient dipstick applications, which could achieve a rapid fluorescence response to anions and amino acids and suggested its very good application prospects. [ABSTRACT FROM AUTHOR]

Copper complexes are considered as potential candidates for anticancer therapy and medical applications. In this paper, three new Cu(II) complexes, [Cu(IPY)2](ClO4)2·H2O (CuI1), [Cu(IPY)(L -Phe)H2O]ClO4·0.5H2O (CuI2) and [Cu(IPY)(L -Val)H2O]ClO4 (CuI3) (where IPY = 2-(1H-imidazol-2-yl)pyridine, L -Phe = L -phenylalanine, and L -Val = L -valine), with good amphipathic properties were synthesized and characterized. Their single crystal X-ray diffraction results revealed that CuI1 was four-coordinated, while CuI2 and CuI3 both adopted a five-coordinated tetragonal pyramidal configuration. Multi-spectral methods, viscosity experiment and molecular docking technique showed that the three complexes interacted with DNA through insertion. The results of the gel electrophoresis experiments indicated that DNA was oxidatively cleaved by all the complexes in a concentration-dependent manner. Moreover, singlet oxygen (1O2), hydrogen peroxide (H2O2) and superoxide anion radicals (˙O2−) were associated with the oxidative cleavage of DNA. All the complexes also had good binding affinity with human serum albumin (HSA). The MB degradation assay revealed that all complexes could react with H2O2 to form ˙OH through Fenton-like processes. The complexes displayed good antiproliferative activity against the tested human cancer cells in vitro, including cervical carcinoma cells (HeLa), liver cancer cells (HepG2 and BEL-7402) and gastric adenocarcinoma cells (SGC-7901), but showed lower toxicity to normal liver cells (LO2). The anticancer mechanism research revealed that CuI1, CuI2 and CuI3 arrested the cell cycle at the S phase, elevated intracellular reactive oxygen species (ROS) levels and induced loss of mitochondrial membrane potential (MMP). The results indicated that these Cu(II) complexes could induce DNA damage and ROS-mediated mitochondrial dysfunction, leading to cancer cell apoptosis. Our work provides a theoretical basis for the design of new low-toxicity and highly efficient anticancer Cu(II) complexes by incorporating biological metabolites and aromatic heterocyclic ligands. [ABSTRACT FROM AUTHOR]

Protocellular surface formation via the self-assembly of amphiphiles, and catalysis by simple peptides/proto-RNA are two important pillars in the evolution of protocells. To hunt for prebiotic self-assembly-supported catalytic reactions, we thought that amino-acid-based amphiphiles might play an important role. In this paper, we investigate the formation of histidine-based and serine-based amphiphiles under mild prebiotic conditions from amino acid : fatty alcohol and amino acid : fatty acid mixtures. The histidine-based amphiphiles were able to catalyze hydrolytic reactions at the self-assembled surface (with a rate increase of ∼1000-fold), and the catalytic ability can be tuned by linkage of the fatty carbon part to histidine ( N -acylated vs . O -acylated). Moreover, the presence of cationic serine-based amphiphiles on the surface enhances the catalytic efficiency by another ∼2-fold, whereas the presence of anionic aspartic acid-based amphiphiles reduces the catalytic activity. Ester partitioning into the surface, reactivity, and the accumulation of liberated fatty acid explain the substrate selectivity of the catalytic surface, where the hexyl esters were found to be more hydrolytic than other fatty acyl esters. Di-methylation of the -NH 2 of OLH increases the catalytic efficacy by a further ∼2-fold, whereas trimethylation reduces the catalytic ability. The self-assembly, charge-charge repulsion, and the H-bonding to the ester carbonyl are likely to be responsible for the superior (∼2500-fold higher rate than the pre-micellar OLH) catalytic efficiency of O -lauryl dimethyl histidine (OLDMH). Thus, prebiotic amino-acid-based surfaces served as an efficient catalyst that exhibits regulation of catalytic function, substrate selectivity, and further adaptability to perform bio-catalysis.

Sensing and visualization of metabolites and metabolic pathways in situ are significant requirements for tracking their spatiotemporal dynamics in a non-destructive manner. The shikimate pathway is an important cellular mechanism that leads to the de novo synthesis of many compounds containing aromatic rings of high importance such as phenylalanine, tyrosine, and tryptophan. In this work, we present a cost-effective and extraction-free method based on the principles of stable isotope-coupled Raman spectroscopy and hyperspectral Raman imaging to monitor and visualize the activity of the shikimate pathway. We also demonstrated the applicability of this approach for nascent aromatic amino acid localization and tracking turnover dynamics in both prokaryotic and eukaryotic model systems. This method can emerge as a promising tool for both qualitative and semi-quantitative in situ metabolomics, contributing to a better understanding of aromatic ring-containing metabolite dynamics across various organisms. [ABSTRACT FROM AUTHOR]

The synthesis of nanosized ZSM-5 zeolites with high crystallinity and suitable acidity is very significant for their great potential in various catalytic applications. Herein, a series of zeolite ZSM-5 crystals with different particle sizes and SiO2/Al2O3 ratios (10-30) were synthesized by a temperature-varying two-step crystallization method in a concentrated gel system containing L-lysine and/or polyvinylpyrrolidone (PVP) additives. By optimizing the addition amounts of the two additives, the crystal size of the ZSM-5 zeolite could be reduced to less than 100 nm. Meanwhile, relatively high crystallinity and framework Al incorporation rates could be achieved, resulting in the generation of high-quality ZSM-5 nanocrystals. The nanosized H-form ZSM-5 zeolite with a SiO2/Al2O3 ratio of 20 showed enhanced catalytic efficiency and stability for the alkylation of 2-methylnaphthalene (2-MN) with methanol to produce an important intermediate, 2,6-dimethylnaphthalene (2,6-DMN). A relatively high and steady yield of 2,6-DMN (above 7.2%) could be achieved during 20 h time-on-stream at 400 °C. The smaller crystal size, higher crystallinity and framework Al content could provide more accessible Brønsted acid sites in the 10-membered ring channel of the ZSM-5 nanocrystals, which are the main active sites responsible for the shape-selectivity of the targeted product of 2,6-DMN. As a result, the formation of other side products like 1-MN and poly-MN could be effectively inhibited, thus leading to an improved 2,6-DMN yield and coke resistance over the nanosized ZSM-5 catalyst. [ABSTRACT FROM AUTHOR]

Biodegradable plastics, represented by polylactic acid (PLA), are considered suitable alternatives to nondegradable commodity plastics; however, their degradation through microbial decomposition is seen as a waste of carbon resources and inevitably brings about CO2 emission. Alternatively, waste PLA plastics can be utilized as feedstocks for the sustainable production of value-added chemicals, which not only avoids a carbon footprint but also realizes upcycling of plastic waste. Here, we show a cascade system that combines alkali-induced depolymerization, pulsed electrooxidation, and electrochemical reductive amination to produce alanine with an overall yield of 69% under near ambient conditions. Specifically, we first implement an alkali catalyst in an aqueous solution to depolymerize PLA into lactate. The obtained PLA hydrolysate is directly utilized as both feedstock and electrolyte for pyruvate production over a nickel hydroxide-supported Pd electrocatalyst (Pd/Ni(OH)2) via a pulsed potential, which is followed by the transformation of pyruvate into alanine using a TiO2 catalyst. This cascade process for alanine production benefits from high efficiencies maintained in three consecutive processes, mild operation conditions, and the use of cost-effective feedstocks (plastic wastes), without suffering harsh conditions and expensive feedstock consumption required by conventional biological and chemical approaches for alanine synthesis, respectively. [ABSTRACT FROM AUTHOR]

A novel and efficient method for the modification of amino acids using a dimethyl carbonate (DMC) and acid system has been developed. N-Methylation, N,O-dimethylation, and N-formylation of various amino acids have been successfully achieved using this simple acid-assisted method (>99% conversions and >99% yields) and the modified amino acids were fully characterized using NMR spectroscopy. This method offers several advantages, including the use of a sustainable and cost-effective reagent, high selectivity, efficiency, eco-friendliness, broad applicability to a range of amino acids with different side chain functionalities, and being secure in the knowledge that there is no risk of racemization and epimerization. This study provides a new, sustainable, and practical approach for the modification of amino acids, which has potential applications in drug discovery and chemical biology. [ABSTRACT FROM AUTHOR]

Photoelectron-photoion(s) coincidence, PEPICO, experiments with synchrotron radiation have become one of the most powerful tools to investigate dissociative photoionization thanks to their selectivity. In this paper their application to the study of molecular species of biological interest in the gas phase is reviewed. Some applications of PEPICO to the study of potential radiosensitizers, amino acids and small peptides and opportunities offered by the advent of novel methods for the production of beams of these molecules are discussed.

A new benzothiazole azo dye [(E)-1-((6-methoxybenzo[d]thiazole-2-yl)diazenyl)naphthalene-2,6-diol] (also known as “BAN”), has been synthesised and used as a chemosensor for the rapid and selective detection of mercury(ii) ions in water. The pink coloured chemosensor turns blue when reacted with mercury(ii) ions due to the formation of a 2 : 1 coordination complex. The complex formation causes a bathochromic shift of the chemosensor's UV absorption peak from 540 to 585 nm and turns on a highly selective fluorescence emission at 425 nm. The change in the optical property of BAN upon complexation with mercury(ii) was confirmed by ab initio calculations. The new chemosensor was used to quantify mercury(ii) ions in water by fluorescence spectroscopy down to 5 × 10−8 M (10 ppb). The limit of detection (LOD) of Hg2+ was 9.45 nM (1.8 ppb) which satisfies the maximum allowable Hg2+ concentration in drinking water that is set by the WHO. The BAN–Hg(ii) complex was used for the determination of cysteine (Cys) in aqueous solution by UV-Vis spectroscopy down to 1 × 10−7 M. The thiol-containing amino acid preferentially coordinates the mercury ions of the BAN–Hg(ii) complex. This causes dissociation of the blue-coloured complex and the liberation of the pink-coloured BAN dye. The colour change of the BAN–Hg(ii) complex from blue to pink was selective to the Cys biothiol while other non-thiol containing amino acids did not cause a colour change. For the in-field application, filter paper strips were loaded with the BAN–Hg(ii) complex and used as a disposable sensor for the detection of cysteine (Cys) by the naked eye. Therefore, the BAN chemosensor offers a sensitive, and rapid tool for the detection of mercury(ii) in water. In addition, the BAN–Hg(ii) complex can be used as a simple and selective chemosensor of the screening of purified biothiols, such cysetine, homocysteine and glutathione in biology research and pharmaceutical/food industries. [ABSTRACT FROM AUTHOR]

The stability of a protease is crucial for its application in biological processes and various industries. This study aims to improve the stability of serine protease PB92 by introducing disulfide bonds. Using the Disulfide by Design 2 online server, we predicted appropriate cysteine pairs and introduced three pairs of amino acid mutations, resulting in their conversion to cysteines and subsequent formation of disulfide bonds. Additionally, to comprehensively assess the effects of combined mutations, three additional mutations were generated by combining the aforementioned three pairs of mutations. Molecular Dynamics (MD) simulations were performed to evaluate the influence of the introduced mutations. The results demonstrated that the mutant with disulfide residues A71C–A86C and T249C–L261C exhibited higher stability compared to both the wild type and other mutants. Docking results indicated that the introduced mutations did not affect the binding performance of the protease. [ABSTRACT FROM AUTHOR]

Analytical and preparative separation techniques, although perceived as less detrimental compared to industrial manufacturing processes, present a substantial concealed environmental threat. Green analytical chemistry has seen major advances in the past five years in terms of proposing metrics for measuring the greenness of separation methods. One such comprehensive measure is the Analytical Method Greenness Score (AMGS), which was used to benchmark current enantiomeric separation methods in the literature. In this work, we propose pragmatic and mathematical strategies to minimize AMGSs in high-performance liquid chromatographic enantioseparations. A case study of more than 456 chromatograms from the enantiomers of 38 proteo- and non-proteogenic amino acids was generated and assessed. A sustainable method of generating carbonated water-based eluents was introduced, and the H2CO3* additive was shown to improve the chromatographic figures of merit (resolution and efficiency) while lowering the AMGS. We show that narrow diameter columns with superficially porous particles reduced the solvent waste 12-fold compared to traditional analyses. The AMGS formula was modified to incorporate the "cycle time" of the chromatograph, which provides a more accurate picture of solvent waste generation in high throughput chemical analyses. Using the principles of mathematical optimization, the AMGS was minimized with respect to flow rate to show that the ideal separation speed differs depending on the solvent composition. The AMGS reached values as low as 1.2 for ultrafast (<15 s) amino acid chiral separations, where 79% was contributed by the cycle time. This AMGS minimization adds a new optimization problem to future method development, with widespread implications for drug development research and other production fields reliant on separation sciences. [ABSTRACT FROM AUTHOR]

Host–guest chemistry within the confined space of metal–organic frameworks (MOFs) offers an almost unlimited myriad of possibilities, hardly accessible with other materials. Here we report the synthesis and physical characterization, with atomic resolution by single-crystal X-ray diffraction, of a novel water-stable tridimensional MOF, derived from the amino acid S-methyl- L -cysteine, {SrZn6[(S,S)-Mecysmox]3(OH)2(H2O)}·9H2O (1), and its application as a robust and efficient solid catalyst for the cycloaddition reaction of ethylene/propylene oxide with CO2 to afford ethylene/propylene carbonate with yields of up to 95% and selectivity of up to 100%. These results nicely illustrate the great potential of MOFs to be game changers for the selective synthesis of industrially relevant products, representing a powerful alternative to the current heterogeneous catalysts. [ABSTRACT FROM AUTHOR]

UV-Vis absorption spectra and emission peaks of indole and 7-fluoroindole are measured and it is observed that 7-fluoroindole quenches the fluorescence signals significantly compared to indole. This observation is elucidated via reconstruction of the potential energy surfaces, determination of the conical intersections, and dynamical studies. It is observed that a single fluorine substitution on indole leads to the appearance of several accessible low-energy conical intersections that cause fast nonradiative decay. In this paper, we have investigated the nonradiative processes of Ind and 7F-Ind theoretically using high-level methods, such as EOM-EE-CCSD, SA-CASSCF, MS-CASPT2/6-311++G(d,p) levels of theory, to study these pathways and their feasibility.

L -Cysteine is a common amino acid that plays an important role in human livelihood and production. Therefore, a novel method for the simultaneous quantitative and qualitative determination of L -cysteine by a colorimetric detection system is proposed. As a viable oxidase mimic, [N4444]Cl-G/MnO2, which consisted of MnO2 nanosheets functionalized by a tetrabutylammonium chloride–glycerol ([N4444]Cl-G) based deep eutectic solvent (DES) was fabricated. Owing to the oxidation of MnO2 nanosheets, [N4444]Cl-G/MnO2 could oxidize the colorless 3,3′,5,5′-tetramethylbenzidine (TMB) into a blue product (oxTMB) with the characteristic UV–vis spectrum absorbance at 652 nm. The oxidation of TMB by DES/MnO2 was inhibited when L -cysteine was introduced, and the absorbance decreased proportionally with the increase in L -cysteine concentration. Due to this inhibition effect, a colorimetric detection system ([N4444]Cl-G/MnO2-TMB) was developed for the quantitative determination of L -cysteine. Under optimal conditions, the assay showed good linearity over the concentration range of 0.125–2.00 μg mL−1 with a low detection limit of 5.96 ng mL−1. A study of the inhibition mechanism demonstrated that the sulfhydryl group of L -cysteine could decompose [N4444]Cl-G/MnO2 into Mn2+, thus limiting the conversion of TMB to oxTMB. In addition, the [N4444]Cl-G/MnO2-TMB system was used in test strips for the visual qualitative detection of L -cysteine. The selectivity and test strip results demonstrated the high selectivity, simple operation, and rapid response of the [N4444]Cl-G/MnO2-TMB system for the qualitative detection of L -cysteine. Given the satisfying performance of the detection strategy, colorimetric sensing based on the [N4444]Cl-G/MnO2-TMB system is considered to have prospective application value in the quantitative and qualitative detection of L -cysteine. [ABSTRACT FROM AUTHOR]

Glycine is the simplest proteinogenic amino acid. It has significant astrobiological implications owing to the ongoing investigation for its detection in the interstellar medium (ISM). Hence, a suitable mechanistic elucidation for its formation in the ISM is of current research interest. In the present work, by employing electronic structure calculations [UCCSD(T) and density functional theory (DFT)], various plausible chemical pathways in the gas phase have been examined for the formation of glycine (whose existence has been indirectly proposed in the ISM) and other simple amino acids (yet to be detected in the ISM) from some simpler molecules present in the ISM. This work suggests that step 1: HO-CO (radical) + CH 2 NH → NHCH 2 COOH (radical) and step 2a: NHCH 2 COOH (radical) + H 2 → glycine + H (radical) have very small barriers of 0.14 kcal mol -1 and ∼3 kcal mol -1 , respectively (easily surmountable at a temperature of ∼50 K under putative interstellar conditions). Hence this should likely be feasible in interstellar gas-phase chemistry. Therefore, HO-CO (radical), CH 2 NH, and H 2 could be the possible precursors for the formation of glycine (subject to the presence of the HO-CO radical). The energetic information related to the interstellar reactions, and how this work takes the putative interstellar conditions into account are presented. This paper also highlights how a reaction found to be unsuitable for interstellar molecular evolution via surface chemistry could nonetheless occur via gas-phase chemistry. Based on our results, this work also recommends detecting three new open-shell molecules, HO-CO radical, NHCH 2 COOH radical, and NH 2 CHCOOH radical, in the ISM.

Isoindolinone is a constituent of various natural products and synthetic biologically active compounds. The classical multi-step synthetic methods used to prepare various indolinone derivatives are tedious and challenging. One-pot synthetic methods are attractive and economical. Transition-metal-catalyzed C-H activation is an emerging tool for synthesizing natural products and small organic molecules via reducing the number of synthetic steps necessary. This paper describes the synthesis of N -alkyl-3-methenyl chiral isoindolinone derivatives from aryl amides of L-amino acids and non-activated alkene via Pd-catalyzed C(sp 2 )-H olefination. Herein, the amino acid residue acts as a directing group for olefination at the aryl ring, and then cyclization occurs at the amide NH. Hence, this methodology could be helpful to transform standard amino acids into respective chiral isoindolinone derivatives.

Recently, amino acids other than glycine and taurine were found to be conjugated with bile acids by the gut microbiome in mouse and human. As potential diagnostic markers for inflammatory bowel disease and farnesoid X receptor agonists, their physiological effects and mechanisms, however, remain to be elucidated. A tool for the rapid and comprehensive annotation of such new metabolites is required. Thus, we developed a semi-empirical MS/MS library for bile acids conjugated with 18 common amino acids, including alanine, arginine, asparagine, aspartate, glutamine, glutamate, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, and valine. To investigate their fragmentation rules, these amino acids were chemically conjugated with lithocholic acid, deoxycholic acid, and cholic acid, and their accurate-mass MS/MS spectra were acquired. The common fragmentation patterns from the amino acid moieties were combined with 10 general bile acid skeletons to generate a semi-empirical MS/MS library of 180 structures. Software named BAFinder 2.0 was developed to combine the semi-empirical library in negative mode and the characteristic fragments in positive mode for automatic unknown identification. As a proof of concept, this workflow was applied to the LC-MS/MS analysis of the feces of human, beagle dogs, and rats. In total, 171 common amino acid-conjugated bile acids were annotated and 105 of them were confirmed with the retention times of synthesized compounds. To explore other potential bile acid conjugates, user-defined small molecules were in-silico conjugated with bile acids and searched in the fecal dataset. Four novel bile acid conjugates were discovered, including D -Ala- D -Ala, Lys(iso)-Gly, L -2-aminobutyric acid, and ornithine. [ABSTRACT FROM AUTHOR]

A novel metal–organic framework (MOF) Zn-PBC (H2PBC = pyridine-3,5-bis(phenyl-4-carboxylic acid)) was designed and synthesized via a solvothermal reaction with the H2PBC ligand, and produced a strong fluorescence. The material exhibited good stability and an ideal luminescent property in water. In addition, it was found that Zn-PBC displayed a different fluorescent response to different types of amino acids, and the mechanism was investigated. This research might give insight to the interaction between MOFs and amino acids, which would provide a strategy to fabricate MOF-based sensors for biomolecules in future. [ABSTRACT FROM AUTHOR]

Particular interest has been focused on the modulation of solid state charge transport in proteins via π–π interactions. Nevertheless, molecular design with the π–π interaction mode for electronic applications remains a challenge in light of the complexity of protein structures. Here, we investigate the pattern of regulating peptide charge transport via different types of π–π interactions in peptide-based frameworks. We applied aromatic amino acid containing peptides labelled with a 1-methyl-1′-aminoethyl-4,4′-bipyridinium salt (MV2+) to construct well-defined self-assembled monolayers as the model. When the π–π interactions are improved by the size of aromatic amino acid side chains, the peptide charge transport can be promoted mainly by the reduced energy barrier and not by the weakened peptide−electrode coupling. When the π–π interactions are attenuated rapidly by increasing the distance between aromatic groups, the molecule–electrode coupling is enhanced sharply, which becomes the main factor to facilitate the charge transport. [ABSTRACT FROM AUTHOR]

A one-step protocol for the automated flow synthesis of protected glycosylated amino acids is described using pumps with open-source controls in overall yields of 21–50%. The resulting glycosylated amino acids could be used directly in solid-phase peptide synthesis (SPPS) protocols to quickly produce glycopeptide standards. Access to a variety of stereoisomers of the sugar enabled the development of an LC-MS/MS protocol that can distinguish between peptides modified with carbohydrates having the same exact mass. This method could definitively identify fucose in an O-glycosylation site on the transmembrane protein, Notch1. [ABSTRACT FROM AUTHOR]

Chiral amino-group compounds are of significance for human health, such as biogenic amino acids (AAs), dipeptides, and even various drugs. Enantiospecific discrimination of these chiral compounds is vital in diagnosing diseases, identifying pathological biomarkers and enhancing pharmaceutical chemistry research. Here, we report a simple and rapid 19F NMR-based strategy to differentiate chiral AAs, dipeptides, and amines, that were derivatized with (R)-2-(2-fluorophenyl)-2-hydroxyacetic acid ((R)-2FHA). As a result, 19 proteinogenic AAs (37 isomers) as well as Gly could be concurrently resolved. Moreover, various mirror-image dipeptides, such as Ser–His, Leu–Leu, and Ala–Ala, were commendably recognized. Intriguingly, we found that the absolute configuration of AAs in the N-terminus of dipeptides decided the relative 19F chemical shifts between two enantiomers. Besides, the ability of this method for enantiodiscrimination was further demonstrated by non-AA amines, including aromatic and aliphatic amines, and even amines having chiral centers several carbons away from the amino-group. The structurally similar antibiotics, amoxicillin and ampicillin, were well discriminated. Furthermore, this method accurately determines the de or dr values of non-racemic mixtures. Therefore, our strategy provides an effective approach for 19F NMR-based enantiodiscrimination and diastereomeric purity determination of amino-group compounds. [ABSTRACT FROM AUTHOR]

A metal free, visible-light driven α-C(sp3)–H gem-difluoroallylation of glycine derivatives with trifluoromethyl alkenes and 1,3-enynes is presented. This protocol features mild and redox-neutral conditions, broad substrate scope, excellent functional group compatibility, as well as high atom-efficiency, thus offering a sustainable and practical strategy to access fluorine-containing unnatural amino acids and peptides. The good scalability and excellent compatibility with biomolecules further highlight the potential utility of this protocol. [ABSTRACT FROM AUTHOR]

Since anthrax spores are highly lethal to human beings and animals, and also potential biological warfare agents, it is highly desirable to develop simple, robust and easy-device sensors that are rapid and sensitive, and can selectively detect the Bacillus anthrax biomarker dipicolinic acid (DPA) quantitatively. Herein, we report a ratiometric luminescent “turn-on” sensor via mixing Eu3+ ions, sodium polyacrylate and internal luminescence reference in water, which can identify the Bacillus anthrax biomarker dipicolinic acid (DPA) quantitatively with outstanding selectivity over aromatic ligands and amino acids, even including all of the 5 DPA isomers. [ABSTRACT FROM AUTHOR]

Self-assembling peptides are of huge interest for biological, medical and nanotechnological applications. The enormous chemical variety that is available from the 20 amino acids offers potentially unlimited peptide sequences, but it is currently an issue to predict their supramolecular behavior in a reliable and cheap way. Herein we report a computational method to screen and forecast the aqueous self-assembly propensity of amyloidogenic pentapeptides. This method was found also as an interesting tool to predict peptide crystallinity, which may be of interest for the development of peptide based drugs. [ABSTRACT FROM AUTHOR]

Lead halide hybrid perovskites incorporating chiral organic cations attract considerable attention due to their promising application in multifarious optoelectronic devices. However, the examples of chiral hybrid perovskites are still limited, which greatly impedes their further studies in various optoelectronic fields. Herein, we report on new low-dimensional lead-halide hybrid perovskites incorporating the enantiopure chiral α-amino acid L -proline. Two hybrid perovskites (L -proH)PbBr3·H2O (Pro-PbBr3) and (L -proH)4Pb3Br10·4H2O (Pro-Pb3Br10) have been synthesized by employing different ratios of organic and inorganic precursors. According to structural analysis, the inorganic sublattice of compound Pro-PbBr3 is built of one-dimensional (1D) [PbX3]∞n− lead halide chains, whereas the inorganic sublattice of compound Pro-Pb3Br10 is built upon a rare two-dimensional (2D) [Pb3Br10]∞4n− honeycomb-type inorganic framework. Hirshfeld surface analysis revealed an important role of various hydrogen bonding interactions in providing the binding between organic and inorganic parts of these hybrid perovskites. The optical band gap values of new hybrid perovskites as estimated using the Tauc plot approach are 4.19 eV (Pro-PbBr3) and 4.13 eV (Pro-Pb3Br10). Also, new compounds display low-temperature broadband photoluminescence which can be attributed to the self-trapped excitons. These results show the potential of α-proline for constructing novel and highly demanded chiral hybrid perovskites, which will hold great promise for further optoelectronic applications. [ABSTRACT FROM AUTHOR]

Seed proteins, especially those of amaranth, are characterized using different peptides with important biological functions. The aim of this work is to describe, at a theoretical–experimental level, the selective separation of encrypted peptides with high-added value. The interactions between amino acid–PAMAM and peptide–PAMAM were determined using quantum chemistry and instrumental techniques of structural analysis, with the obtained results showing correlation between both methods of identification and characterization. The molecular properties of amino acids, peptides (models) and PAMAM were determined using density functional theory (DFT), specifically B3LYP and the 6-31G(d,p) basis set. The synthesis of the dendrimer (PAMAM) was carried out by optimizing the traditional process to reduce cost and waste generation. The analysis of the vibrational frequencies between tyrosine and PAMAM using the DFT method correlated satisfactorily with the experimental data. The interaction energy of the most stable complexes was between those of the first generation PAMAM dendrimer, the amino acid tyrosine and the PAMAMAM–YLAGKPQQEH peptide, with a value of −31.25 kcal mol−1 and −27.19 kcal mol−1, respectively. Likewise, the molecular electrostatic potential map and the intermolecular hydrogen bonds allowed visualizing the interactions between the captured atoms (amino acids and peptides) and the synthesized PAMAM. This work showed evidence at the molecular level of selectivity of encrypted oligopeptides. The theoretical study was determined to define the types of peptides that could interact with PAMAM after enzymatic hydrolysis, as well as the type of interaction, and the atoms involved in the formation of a dendrimer–peptide complex. Subsequently, at the experimental level, these residues were mapped by mass spectrometry in a MALDI-TOF detector, having results that can be homologated with the theoretical results. This study opens the door to novel studies for the separation of bioactive peptides. [ABSTRACT FROM AUTHOR]

Fluorescent nanoaggregates (FNAs) based on phenanthroline-based amphiphiles show changes in solution color from colorless to yellow upon addition of both Hg2+ (LOD ∼4 ppb) and CH3Hg+ (LOD ∼18 ppb). However, the extent of fluorescence quenching is more prominent with Hg2+ (∼12 fold) than with CH3Hg+ (∼4 fold). Also, unlike Hg2+, the interaction of CH3Hg+ needs more time, ∼10 min at room temperature. Experimental evidence indicates that both mercury species coordinate with the phenanthroline unit and facilitate the charge transfer interaction while destabilizing the nanoassembly. The lower charge density on CH3Hg+ along with its large size compared to Hg2+ may be the reason for such observations. Interestingly, FNAs show a selective response towards CH3Hg+ when pre-treated with EDTA. Further, analysis of heavy metal pollutants in drinking water and biological samples was performed. High recovery values ranging from 96% to 103.0% were estimated along with relatively small standard deviations (<3%). Low-cost, reusable test strips were designed for rapid, on-site detection of mercury species. Further, the in situ formed metal complexes are allowed to interact with thiol-containing amino acids. As expected, CH3Hg+, being less thiophillic, endures less interaction with cysteine. Mechanistic investigations indicate that thiolated amino acids can bind with the metal ion center and form a tertiary complex (cooperative interaction). [ABSTRACT FROM AUTHOR]

We report the production of biobased plasticizers starting from citric acid (CA) by a two-step process comprising dehydration-hydrogenation of CA followed by a Fischer esterification. The use of citric acid based plasticizers is well-known in PVC. However, citrate esters tend to leach out of the PVC material over time. This problem is currently tackled by acetylating the tertiary hydroxyl group of CA via complex and environment polluting processes. Our alternative strategy consists in the removal of the tertiary hydroxyl group, resulting in propane-1,2,3-tricarboxylic acid (PTA). First, dehydration reactions of a large amount of CA (20 mmol) were performed at relatively mild reaction conditions (150 °C and 20 bar H2) using Al2(SO4)3 as a homogeneous catalyst and water as a green solvent. The catalytic system was proven to be robust in time and in the presence of other organic functionalities (e.g. amino acids with different functional groups, diacids). In a second step, the reaction mixture was transferred to a Dean–Stark setup in order to perform a Fischer esterification with n-butanol, during which the previously used Al2(SO4)3 could be recuperated. This resulted in an overall yield of 90% tributyl propane-1,2,3-tricarboxylate (TBPTC), which can be used as a plasticizer in PVC. [ABSTRACT FROM AUTHOR]

Cocrystallization is a crystallization technique for drugs that are difficult to crystallize as single components. In this study, we found a novel cocrystal hydrate consisting of captopril (CPL), which is an amino acid-derived drug and has a thiol group, and L -proline (LPR), although a CPL–LPR cocrystal anhydrate has been previously reported. Nano-spot screening elucidated a new LF Raman spectrum for the combination of CPL and LPR due to the formation of a crystalline complex. Single crystal X-ray diffraction analysis revealed that this crystalline complex was a cocrystal hydrate with a stoichiometric ratio of 1 : 1 : 1 CPL : LPR : H2O in an asymmetric unit. Notably, the CPL–LPR cocrystal hydrate showed high hygroscopicity, and the degradation product of CPL upon a storage stability test could have resulted from the changes in the intermolecular interactions and the location of the water molecules involved in the thiolate formation in the crystal structure. The storage stability tests highlighted a higher amount of CPL degradation product in the CPL–LPR cocrystal hydrate than in the CPL crystal, potentially due to i) increased hygroscopicity, ii) decreased intermolecular interactions that contribute to CPL stabilization and iii) increased reactivity by water molecules for the crystal structure of the CPL–LPR cocrystal hydrate. Therefore, it is suggested to select a coformer with few OH groups involved in the interaction with water or low hygroscopicity to optimize the stable cocrystals of drugs. [ABSTRACT FROM AUTHOR]

Electrocatalytic reductive amination (ERA) offers an attractive way to synthesise organonitrogen chemicals from renewable feedstocks. Here, we report carbon nanotubes (CNTs) as an effective catalyst for the ERA of biomass-derivable α-keto acids into amino acids using NH3 as the nitrogen source. Through a facile ball milling (BM) treatment, the intrinsic defects in the CNTs were increased while the electrocatalytic activity of CNTs converting 2-ketoglutaric acid into glutamic acid was enhanced by approximately seven times. A high faradaic efficiency (FE) of ∼90% with a corresponding glutamic acid formation rate of up to 180.9 mmol g−1cat h−1 was achieved, and ∼60% molar yield of glutamic acid was obtained after 8 h of electrolysis. Electrokinetic analyses indicated that the BM–CNT catalysed ERA exhibits a first-order dependence on the substrate and NH3, with a rate-determining step (RDS) involving the first electron transfer. Following this protocol, a number of amino acids were prepared with moderate to high FEs and formation rates. Significantly, we synthesised long carbon chain amino acids, which are typically obtained in lower yields using the existing methods. [ABSTRACT FROM AUTHOR]

Arguably one of the largest research areas involving carbon dioxide (CO2) fixation is the coupling of CO2 to epoxides to form cyclic carbonates and polycarbonates. In this sense, there is an ever-increasing demand for the development of higher-performing catalytic systems that could counterbalance sustainability and energy efficiency in the production of cyclic carbonates. The use of abundant first-row transition metals combined with naturally occurring amino acids may be an ideal catalytic platform to fulfill this demand. Nevertheless, detailed information on the interactions between metal centers and natural products as catalysts in this transformation is lacking. Here a series of Co(III) amino acid catalysts operating in a binary system showed outstanding performance for the coupling reaction of epoxides and CO2. Nine new complexes of the type trans(N)-[Co(aa)2(bipy)]Cl (aa: ala, asp, lys, met, phe, pro, ser, tyr, and val) were used to explore the structure–activity relationship influenced by the complex outer coordination sphere, and its effect on the catalytic activity in the coupling reaction of CO2 and epoxides. [ABSTRACT FROM AUTHOR]

Herein, a metal- and photosensitizer-free protocol has been developed for decarboxylative C-H (amino) alkylation of heteroarenes using carboxylic acids as the (amino)alkylating reagents. This reaction is performed in a sustainable solvent (dimethyl carbonate, DMC). Various carboxylic acids (tertiary, secondary, and primary carbon) are well tolerated, providing the target products in acceptable yields. More importantly, such an approach can also efficiently convert a wide range of amino acids and carboxyl-containing drugs into desired products. This protocol provides a green and efficient approach for the rapid conversion of abundant feedstock materials into medically relevant "drug-like" moieties. [ABSTRACT FROM AUTHOR]

Covering: up to October 2020 Furanocoumarins are plant secondary metabolites used to treat several skin disorders, such as psoriasis and vitiligo, and also with other potential therapeutic activities. Furanocoumarins are extracted from plants where they accumulate in low amounts over long growth periods. In addition, their extraction and purification are difficult in an environmentally unfriendly and expensive process. Hence, new sustainable and greener production schemes able to overcome such limitations ought to be developed. While the heterologous production of simple coumarins has been demonstrated, the biosynthesis of more complex furanocoumarins remains greatly unexplored. Although several important steps of the pathway have been elucidated in the last decade, the complete pathway has not been completely unravelled. In this paper, we review the natural conversion of amino acids into furanocoumarins, as well as the heterologous expression of each enzyme of the pathway. We also explore the challenges that need to be addressed so that their heterologous production can become a viable alternative. [ABSTRACT FROM AUTHOR]

Samarium macrocycle-based complex Sm-2n, a luminescent matrix bearing two dynamic imine bonds as recognition sites and a Sm(III) emitter as the fluorescence indicator, can selectively probe cysteine over other analogous amino acids and show remarkable turn-off fluorescent character. Moreover, using Sm-2n-impregnated paper-based test strips and RGB outputs, we develop a smartphone-based analysis method to give a convenient approach with satisfactory results for cysteine detection and determination. [ABSTRACT FROM AUTHOR]

An electrochemical chiral sensing platform based on a multi-substituted ferrocene–cuprous ion (Cu+) complex is constructed for the discrimination of electroactive amino acid (AA) isomers. Due to the opposite configurations of the AA isomers, the developed multi-substituted ferrocene–Cu+ can preferably combine with a right-handed AA (D -AA) isomer to form the ternary complex of multi-substituted ferrocene–Cu+- D -AA through π–π interactions, resulting in higher peak currents of D -AA. Therefore, the isomers of electroactive AA can be successfully discriminated. Among the tested electroactive AA isomers, the chiral sensing platform exhibits higher discrimination capability toward the isomers of tryptophan (Trp) than that of tyrosine (Tyr) and cysteine (Cys), which might be ascribed to the stronger π–π interactions between the benzene ring of the multi-substituted ferrocene and the indole ring of the Trp isomers. [ABSTRACT FROM AUTHOR]

The reliable identification and quantitation of phosphorylated amino acids, peptides and proteins is one of the key challenges in contemporary bioanalytical research, an area of particular interest when attempting to diagnose and treat diseases at an early stage. We have developed a synthetic probe for targeting phosphorylated amino acids, based on core–shell submicron-sized particles consisting of a silica core, coated with a molecularly imprinted polymer (MIP) shell. The MIP layer contains a fluorescent probe crosslinker which binds selectively to phosphorylated tyrosine (pY) moieties with a significant imprinting factor (IF) and responds with a "light-up" fluorescence signal. The bead-based ratiometric detection scheme has been successfully transferred to a microfluidic chip format and its applicability to rapid assays has been exemplarily shown by discriminating a pY-terminating oligopeptide against its non-phosphorylated counterpart. Such miniaturised devices could lead to an automated pY or pY N-terminated peptide measurement system in the future. The setup combines a modular microfluidic system for amino acid derivatisation, extraction (by micropillar co-flow) and selective adsorption and detection with the fluorescent MIP core–shell particle probes. A miniaturised optical assembly for low-light fluorescence measurements was also developed, based on miniaturised opto-electronic parts and optical fibres. The emission from the MIP particles upon binding of pY or pY N-terminated peptides could be monitored in real-time. [ABSTRACT FROM AUTHOR]

A rare in situ-generated mononuclear rhenium complex [Re(bpt)(CO)3(NH3)] (1, bpt = 3,5-bis(2-pyridyl)-1,2,4-triazolate) can be used as a "turn-on" luminescent probe for selectively sensing L -histidine against other amino acids. Compound 1 was prepared by reacting Re2(CO)10, 2-cyanopyridine and hydrazine with an in situ formed bpt ligand through cyclization via C–N and N–N couplings with its single-side chelating mode arrayed with respect to the Re center. Compound 1 was highly stable and showed a green light MLCT emission in DMF solution at 507 nm upon excitation at 360 nm. Interestingly, the emission from 1 could be quenched by the addition of metal ions such as Ni2+ and Cu2+ but the emission efficiently recovered with the introduction of histidine. However, histidine could only be selectively detected when a combination of compound 1 and Ni2+ was used. Therefore, the luminescence response of the Ni2+-modified compound 1 could be utilized as a "turn-on" probe for the selective detection of histidine. This work provides a simple method for developing new sensing platforms of a discrete metal complex based on rare in situ generation. [ABSTRACT FROM AUTHOR]

Quaterphenyl-5′-carbaldehyde 1 with metal ion coordination ability was synthesized for the first time and used for chiral analyte-binding and chiroptical sensing. The formation of an imine between 1 and amine analytes, such as alcohol amines, diamines, and amino acids, enabled Zn(II)-assisted chiral transfer from the analyte to the atropisomeric biphenyl unit, thereby amplifying the circular dichroism (CD) signal, leading to discernible Cotton effects in the range of 350–450 nm, with g values on the order of magnitude of 10−3 in MeOH. Linear relationships between the CD amplitude and enantiomer excess (ee) of the analytes were observed, enabling use of 1 as a chiroptical probe for amines. Interestingly, 1 showed a fluorescence response to change in concentrations of L -phenylalaninol ((S)-G1) in the presence of Zn(II) upon excitation at 380 nm. It suggests that 1 could serve as a dual chemosensor for the determination of both the ee and concentration of analytes. The Zn(II)-assisted fluorescence behavior was also subjected to circular polarization luminescence (CPL) measurements. [ABSTRACT FROM AUTHOR]

We report on the preparation of synthetically versatile N-carboxyanhydrides (NCAs) directly from amino acids and CO2 using n-propylphosphonic anhydride. Most of the NCAs were isolated with >95% purity after simple workup, avoiding the need for tedious purification procedures typically required using conventional methods. Because the reagents and conditions employed are mild, tandem reactions with moisture-sensitive NCAs were carried out to transform them into the medicinally active alkaloids tryptanthrin and phaitanthrin A in one pot. A qualitative analysis revealed that our NCA synthesis approach is more green than conventional methods, which all directly or indirectly use the highly poisonous gas phosgene. [ABSTRACT FROM AUTHOR]

This paper describes the consequences of incorporating a constrained heterocyclic aromatic β-amino acid 3-aminothiophenecarboxylic acid (3-Atc) into peptides containing β-turn forming elements such as Pro-Gly motif and the effect on the secondary structural architecture of the entire peptide backbone. Conformational investigations of oligomers comprising an α,β,α peptide sequence were carried out by single-crystal X-ray diffraction, solution-state NMR, nOe-restrained MD simulation and circular dichroism studies. The results suggested that these peptide sequences assume helical architecture. The helical folding in the oligomers was found to be devoid of inter-residual H-bonding, instead found to be stabilized by a co-operative effect of 6-membered H-bonding within the 3-Atc unit and conformational restrictions of individual amino acids in the peptide backbone. [ABSTRACT FROM AUTHOR]

Adenosine A1 receptor (A1AR) and adenosine A2A receptor (A2AAR) are AR isoforms that share high homology but play many different roles in terms of regulating arteriolar pressure and urine flow as well as relieving neurodegenerative disorders. Because A1AR and A2AAR have such varied distributions and biological functions, it is critical to distinguish their inhibitory selectivity to minimize unwanted side effects. Thereby, multiple in silico methodologies were used to reveal interactions between key amino acids and selective inhibitors to elucidate the mechanism of selective inhibition towards A1AR and A2AAR. Our results indicated that although A1AR has conserved PHE171 and ASN254, which are also present in A2AAR, namely PHE168 and ASN253, the two isoforms have different binding patterns towards their inhibitors. Generally, A2AAR inhibitors interact with GLU169 via hydrogen bonds, whereas A1AR inhibitors have no corresponding effect. Taken together, our data comprehensively elaborated the selectivity mechanisms of A1AR and A2AAR inhibition, which presents a reasonable guidance, significant for the rational design of selective inhibitors towards A1/A2AAR. [ABSTRACT FROM AUTHOR]

In this study, a series of poly(amino acid)s materials with amphiphilic properties were synthesized by ring-opening polymerization. In specific solvents, macromolecules can self-assemble to form rod-shape/cubic or spherical morphologies. Drug-loaded nanoparticles were formed with the model drug doxorubicin via physical embedding and chemical bonding, with most of them presenting regular spherical shapes with the particle size less than 200 nm, which meets the size requirements for sustained drug release. CCK-8 experiments proved that the obtained material was non-toxic to normal cells, and because of the presence of cholesterol in the structure with good biocompatibility, the uptake of drug-loaded nanoparticles by HeLa cells was facilitated. In vitro release experiments showed that the prepared nanoparticles exhibited dual responsiveness to pH and temperature, and the kinetics of the drug release was investigated. [ABSTRACT FROM AUTHOR]

To improve sustainability, safety and cost-efficiency of synthetic methodologies, biocatalysis can be a helpful ally. In this work, a novel chemoenzymatic stategy ensures the rapid synthesis of hordenine, a valuable phenolic phytochemical under mild working conditions. In a two-step cascade, the immobilized tyrosine decarboxylase from Lactobacillus brevis (LbTDC) is here coupled with the chemical reductive amination of tyramine. Starting from the abundant and cost-effective amino acid L -tyrosine, the complete conversion to hordenine is achieved in less than 5 minutes residence time in a fully-automated continuous flow system. Compared to the metal-catalyzed N,N-dimethylation of tyramine, this biocatalytic approach reduces the process environmental impact and improves its STY to 2.68 g L−1 h−1. [ABSTRACT FROM AUTHOR]

The analysis of chiral α-amino acids is of great significance in asymmetric synthesis, nutrition, food science, and microbiology. However, the ability of chiral recognition is difficult to achieve. Due to the demand for expensive equipment and skilled operators, traditional methods such as high-performance liquid chromatography are limited. The previously reported methods based on chemical sensor arrays usually cannot carry out the chiral analysis. Here, we developed a novel biosensor array based on the interaction between a suite of host-based luminescent bacteria and amino acids and used linear discriminant analysis to reflect their luminescence response patterns. This biosensor array could effectively discriminate chiral amino acids, including 19 L -amino acids, their corresponding D -enantiomers, and the achiral glycine. In addition, the determination of enantiomeric purity and quantitative ability has been proved. The successful identification of a complex system containing multiple chiral amino acids further demonstrates the superiority of the bioluminescent sensor array. Moreover, this sensor array could efficiently monitor the dynamic composition of free amino acids in the process of milk fermentation. Finally, the bioluminescence response mechanism of the luminescent bacteria for the recognition of chirality was clarified. This approach possessed the advantages of facile construction, high throughput, easy operation, high accuracy and fast response. [ABSTRACT FROM AUTHOR]

A terbium-based metal–organic framework, namely {[Tb2(ADIP)(H2ADIP)(HCOOH)(H2O)2]·2DMF·2H2O}n (Tb-MOF, H4ADIP = 5,5′-(anthracene-9,10-diyl) diisophthalic acid), was synthesized and characterized. The single-crystal structure analysis shows that the Tb-MOF crystallizes in the C2/C space group in the monoclinic system and its asymmetric unit contains two TbIII ions, one ADIP4−, one H2ADIP2−, one coordinating formic acid and two coordination water molecules. Tb-MOF has a three-dimensional porous structure with a porosity of 41.5%. Tb-MOF is a highly selective and sensitive fluorescence turn-on and blue-shift sensor for L -aspartate (Asp), L -glutamine (Glu), Al3+ and Ga3+with detection limits of 0.25, 0.23, 0.069 and 0.079 μM, respectively. Experimental studies and theoretical calculations show that the sensing process is mainly attributed to the energy transfer and the absorbance caused enhancement (ACE) mechanism. Therefore, Tb-MOF is a good multi-response fluorescence sensor for acidic amino acids and Al3+, Ga3+cations. [ABSTRACT FROM AUTHOR]

Carbon capture and utilization is considered a promising approach for introducing CO2 into the chemical value chain, especially in combination with bioenergy applications (BECCU). We report here on the catalytic hydrogenation of CO2 to formic acid in a biphasic reaction system using aqueous solutions of amino acids as the product phase and possible capture solutions for biogenic CO2. The molecular structure of the ruthenium catalyst and the catalyst phase were matched through a combined design process identifying n-dodecanol (lauryl alcohol) as the preferred "green" solvent. A total turnover number (TON) of over 100 000 mole HCOOH per mole of catalyst (46 582 g HCOOH per g of Ru) with minimal contamination of the aqueous phase with metal or organic solvent was obtained. The resulting aqueous solutions attained almost quantitative conversions with up to 0.94 mol formic acid per mol amino acid (ca. 108 g HCOOH per kg). Such solutions may find use directly, or after upgrading, in agricultural applications without the need for energy intensive and costly isolation of pure formic acid. [ABSTRACT FROM AUTHOR]

Homocysteine (Hcy) is an amino acid found in the human body and has the potential to predict cardiovascular risk where timely detection and treatment are very important. In this study, we established a method to combine enzymatic hydrolysis with a colloidal gold lateral flow immunoassay (LFIA) for the detection of total Hcy (tHcy) based on the monoclonal antibody (mAb) 3B3 against S-adenosyl- L -homocysteine (SAH). The 50% inhibitory concentration (IC50) for this mAb against SAH was 2.94 nM with a linear range of 0.73–11.75 nM. The developed LFIA could detect SAH with a vLOD and cLOD of 10 nM and 2.07 nM, respectively. For tHcy detection in serum samples, the LFIA strip was able to detect tHcy after enzymatic hydrolysis, and the results correlated well with that of an enzymatic cycling test kit. [ABSTRACT FROM AUTHOR]