Isotope-dilution LC-MS/MS analysis of the elastin crosslinkers desmosine and isodesmosine in acute cerebral stroke patients

Utilizing chemically synthesized an isotopically labeled internal standard, isodesmosine-¹³C₃,¹⁵N₁, an isotope-dilution LC-MS/MS method was established. Concentrations of desmosine and isodesmosine in plasma of acute cerebral stroke patients and healthy controls were determined. The concentration of desmosines was markedly higher in plasma from acute stroke patients compared with healthy controls. Desmosines are thus novel biomarkers for evaluating the extent of vascular injury after acute cerebral stroke.

Established isotope-dilution LC-MS/MS method suggested that desmosines can be regarded as biomarkers of acute cerebral stroke.     

Bead based facile assay for sensitive quantification of native state green fluorescent protein

A facile method for the quantification of native state protein is strongly required to accurately determine the amount of expressed protein of interest. Here we report a simple bead-based assay, which can sensitively quantify the amount of native state green fluorescent protein using Ni-NTA (nickel-nitrilotriacetic acid)-modified microbead particles. The bead-based method is simple and straightforward to perform and it showed a highly sensitive capability to detect the expressed fluorescent protein because of the enriched fluorescent protein on the beads.

A facile method for the quantification of native state protein is strongly required to accurately determine the amount of expressed protein of interest.     

Quantification of azide groups on a material surface and a biomolecule using a clickable and cleavable fluorescent compound

Here, we propose a novel method for quantifying azide groups on a solid surface and a protein using a clickable and cleavable fluorescent compound. The clickable and cleavable fluorescent compound conjugates with the azide groups on the material surface and the fluorophore is then liberated into the solvent via a cleavage reaction, which can be simply quantified with a conventional fluorometer.

We propose a novel method for quantifying azide groups on a solid surface and a protein.     

Recent advances in the utilization of polyaniline in protein detection: a short review

Various reports have been published based on covalently attaching biomolecules to polyaniline (PANI). The functional groups connected to the surface of polymeric units determine the immobilization method as well as the method of detection. The present mini-review aims at covering recent advances in the field of protein binding and detection using PANI. Several proteins have been attached to the polymer using different immobilization techniques. The application of PANI in protein detection has also been discussed along with the future scope of these materials in diagnosis and detection.

Attachment of biomolecules to polyaniline.     

Chemo- and regioselective cross-dehydrogenative coupling reaction of 3-hydroxycarbazoles with arenols catalyzed by a mesoporous silica-supported oxovanadium

Cross-dehydrogenative coupling between 3-hydroxycarbazoles and 2-naphthols has been achieved by using a mesoporous silica-supported oxovanadium catalyst.

Cross-dehydrogenative coupling between 3-hydroxycarbazoles and 2-naphthols has been achieved by using a mesoporous silica-supported oxovanadium catalyst.     

Immunocapture sample clean-up in determination of low abundant protein biomarkers – a feasibility study of peptide capture by anti-protein antibodies

Immunocapture in mass spectrometry based targeted protein analysis using a bottom-up workflow is nowadays mainly performed by target protein extraction using anti-protein antibodies followed by tryptic digestion. Already available monoclonal antibodies (mAbs) which were developed against intact target proteins (anti-protein antibodies) can capture proteotypic epitope containing peptides after tryptic digestion of the sample. In the present paper considerations when developing a method for targeted protein quantitation through capture of epitope containing peptides are discussed and a method applying peptide capture by anti-protein antibodies is compared with conventional immunocapture MS. The model protein used for this purpose was progastrin releasing peptide (ProGRP), a validated low abundant biomarker for Small Cell Lung Cancer with reference values in serum in the pg mL⁻¹ range. A set of mAbs which bind linear epitopes of ProGRP are available, and after a theoretical consideration, three mAbs (E146, E149 and M18) were evaluated for extraction of proteotypic epitope peptides from a complex sample. M18 was the best performing mAb for peptide capture by anti-protein antibodies, matching the LOD (54 pg mL⁻¹) and LOQ (181 pg mL⁻¹) of the existing conventional immunocapture LC-MS/MS method for determination of ProGRP. Peptide and protein capture using the same mAb were also compared with respect to sample clean-up, and the peptide capture workflow yielded cleaner extracts and therewith less complex chromatograms. Analysis of five patient samples demonstrated that peptide capture by anti-protein antibodies can be used for the determination of various levels of endogenously present ProGRP.

Targeted protein biomarker determination by immunocapture LC-MS/MS: comparison of peptide and protein capture using anti-protein antibodies.     

Solvent- and transition metal-free amide synthesis from phenyl esters and aryl amines

A general, economical, and environmentally friendly method of amide synthesis from phenyl esters and aryl amines was developed. This new method has significant advantages compared to previously reported palladium-catalyzed approaches. The reaction is performed transition metal- and solvent-free, using a cheap and environmentally benign base, NaH. This approach enabled us to obtain target amides in high yields with high atom economy.

A new environmentally friendly approach to transition metal- and solvent-free amide synthesis from aryl esters and aryl amines is described.     

Copper-catalyzed transformation of alkyl nitriles to N-arylacetamide using diaryliodonium salts

This work reports a simple and efficient method for the copper-catalyzed redox-neutral transformation of alkyl nitriles using eco-friendly diaryliodonium salts and leading to N-arylacetamides. The method features high efficiency, broad substrate scope and good functional group tolerance.

In this study, a simple and efficient method for the copper-catalyzed redox-neutral transformation of alkyl nitriles using eco-friendly diaryliodonium salts and leading to N-arylacetamides was investigated.     

Nanodeformations of microcapsules: comparing the effects of cross-linking and nanoparticles

The mechanical properties of proteinaceous and composite microcapsules loaded with oil were measured by SFM and evaluated using the Reissner model. Comparison of the obtained results reveals significantly higher Young’s moduli of protein capsules due to intermolecular crosslinking. In contrast, conformational restrictions in composite microcapsules inhibit protein crosslinking leading to the reduction of their elasticity.

SFM results for protein and composite microcapsules are evaluated by the Reissner model. Protein capsules show higher Young’s moduli due to crosslinking, which is absent in composite capsules because of restrictions in the protein conformations.     

One-pot analysis of enantiomeric excess of free amino acids by electrospray ionization mass spectrometry

An electrospray ionization mass spectrometric method for the simultaneous analysis of the enantiomeric excess of free amino acids, without chromatographic separation, was demonstrated using a quasi-racemic mixture of deuterium-labelled and unlabelled chiral copper(ii) complexes. This convenient method enables the simultaneous high-sensitivity determination of the enantiomeric excess of 12 amino acids.

A mass spectrometric method for the simultaneous analysis of the enantiomeric excess of free amino acids, without chromatographic separation, was demonstrated using a quasi-racemic mixture of deuterium-labelled and unlabelled chiral Cu(ii) complexes.     

One-pot three component synthesis of 5-allyl-1,2,3-triazoles using copper(i) acetylides

One-pot three-component reactions using copper(i) acetylide, azide, allyl iodide, and NaOH have been developed. The reactions proceed smoothly at room temperature to afford 5-allyl-1,2,3-triazoles, which can be further transformed into a variety of 1,2,3-triazole-fused bi-/tricyclic scaffolds. This method offers the most efficient, convenient, and practical route towards useful polycyclic scaffolds in moderate to excellent yields.

A one-pot three-component synthetic route toward 5-allyl-1,2,3-triazoles using copper(i) acetylide has been developed, which allows further transformation to important tricyclic scaffolds.     

A mild and efficient method for the synthesis of pyrroles using MIL-53(Al) as a catalyst under solvent-free sonication

A highly efficient method for the synthesis of pyrroles using MIL-53(Al) as a catalyst has been developed under solvent-free sonication. This reaction has a broad substrate scope and high yields were obtained within a short reaction time. Remarkably, no additional additives and volatile organic solvent are required for this method and the MIL-53(Al) could be recovered and reused several times without significant drop-off in catalytic activity.

Catalytic activity of MIL-53(Al) in the synthesis of pyrroles under solvent-free sonication.     

Ru(ii)-catalyzed C6-selective C–H acylmethylation of pyridones using sulfoxonium ylides as carbene precursors

In this study, we describe a method using sulfoxonium ylides as carbene precursors to achieve C6-selective acylmethylation of pyridones catalyzed by a ruthenium(ii) complex. This approach featured mild reaction conditions, moderate to excellent yields, high step economy, and had excellent functional group tolerance with good site selectivity. Besides, gram-scale preparation, synthetic utility, and mechanistic studies were conducted. It offers a direct and efficient way to synthesize pyridone derivatives.

In this study, we describe a method using sulfoxonium ylides as carbene precursors to achieve C6-selective acylmethylation of pyridones catalyzed by a ruthenium(ii) complex.     

Chlorotrifluoroethylidenes: an efficient and convenient approach to their synthesis

A convenient one step synthesis of chlorotrifluoroalkyl olefins starting from aldehydes was developed. The stable reagent 2-((1-chloro-2,2,2-trifluoroethyl)sulfonyl)benzothiazole was prepared from readily available benzothiazole-2-thiol and halothane. This method comprises using stable 2-((1-chloro-2,2,2-trifluoroethyl)sulfonyl)benzothiazole according to the Julia procedure and presents new opportunities for the synthesis of trifluoroalkylidene derivatives.

A convenient one step synthesis of chlorotrifluoroalkyl olefins starting from aldehydes was developed.     

DIBALH: from known fundamental to an unusual reaction; chemoselective partial reduction of tertiary amides in the presence of esters

This study presents a quick and reliable approach to the chemoselective partial reduction of tertiary amides to aldehydes in the presence of readily reducible ester groups using commercial DIBALH reagent. Moreover, the developed method was also extended to multi-functional molecules bearing ester moieties, which were successfully chemoselectively reduced to the corresponding aldehydes.

Highly chemoselective partial reduction of tertiary amides to aldehydes over esters are reported with commercial DIBALH. Various aldehydes are synthesized in excellent yields.     

ZnCl2-promoted domino reaction of 2-hydroxybenzonitriles with ketones for synthesis of 1,3-benzoxazin-4-ones

A ZnCl₂-promoted synthesis of 1,3-benzoxazin-4-one from 2-hydroxybenzonitriles and ketones was developed. This method displays facile access to a diverse range of substituted 1,3-benzoxazin-4-ones in good yields. This synthetic protocol has advantages: (i) easy availability of starting material; (ii) strong corrosive acid-free condition; (iii) high yield.

A method for the synthesis of 1,3-benzoxazine-4-ketone was developed using 2-hydroxybenzonitriles and ketones as raw materials with the promotion of ZnCl₂.     

Iodine-catalyzed synthesis of benzoxazoles using catechols,ammonium acetate,and alkenes/alkynes/ketones via C–C and C–O bond cleavage

An efficient metal-free synthesis strategy of benzoxazoles was developed via coupling catechols, ammonium acetate, and alkenes/alkynes/ketones. The developed methodology represents an operationally simple, one-pot and large-scale procedure for the preparation of benzoxazole derivatives using molecular iodine as the catalyst.

A metal-free one-pot multi-component method for the efficient synthesis of 2-aryl benzoxazoles via coupling of catechols, ammonium acetate and alkenes/alkynes/ketones using an I₂–DMSO catalyst system is illustrated.     

Metal-free catalytic hydrocarboxylation of hexafluorobut-2-yne

An efficient method for stereoselective synthesis of trifluorinated enol esters catalyzed by base was introduced. The DFT calculations and experimental results both supported the nucleophilic addition process. The protocol featured mild reaction conditions and showed a wide functional group tolerance. The one-pot simultaneous etherification and esterification of the salicylic acids further demonstrated the prospective synthetic application.

An efficient method for stereoselective synthesis of trifluorinated enol esters catalyzed by base was introduced.     

Copper-catalyzed synthesis of 2-aminopyridylbenzoxazoles via domino reactions of intermolecular N-arylation and intramolecular O-arylation

A simple and general approach to nitrogen-containing heterocycles via copper-catalyzed domino reaction has been developed, and the corresponding 2-aminopyridylbenzoxazole derivatives were obtained in good to excellent yields using the readily available starting materials. This method possesses unique step economy features, and is of high tolerance towards various functional groups in the substrates.

A simple and general approach to nitrogen-containing heterocycles via copper-catalyzed domino reaction has been developed, the corresponding 2-aminopyridylbenzoxazole derivatives were obtained in good to excellent yields using the readily available starting materials.     

Novel synthesis of benzotriazolyl alkyl esters: an unprecedented CH2 insertion

We have developed a novel method for the synthesis of benzotriazolyl alkyl esters (BAEs) from N-acylbenzotriazoles and dichloromethane (DCM) under mild conditions. This reaction is one of few examples to show the use of DCM as a C-1 surrogate in carbon–heteroatom bond formation and to highlight the versatility of using DCM as a methylene building block.

Versatile synthesis of benzotriazolyl alkyl esters (BAEs) from N-acylbenzotriazoles using DCM as a methylene building block.