Quantification of L‐ergothioneine in whole blood by hydrophilic interaction ultra‐performance liquid chromatography and UV‐detection

A new hydrophilic interaction ultra‐performance LC method was established for the whole blood measurement of L‐ergothioneine. Chromatographic separation was achieved in a fairly short time, less than 4 min, on a 100 × 2.1 mm Acquity UPLC BEH HILIC 1.7 μm column with a mobile phase consisting of a mixture of 100 mmol/L ammonium acetate/ACN/water (5:85:10, v/v/v) that flowed isocratically at 0.250 mL/min. The LOD and the limit of quantification were 3.85 and 11.67 μmol/L, respectively. The method exhibited linearity in a concentration range of 15.63–1000 μmol/L (R² > 0.999). Mean recovery was 96.34% whereas intraassay and interassay precision were 1.52 and 1.82% RSD, respectively. On the whole, the developed method is simple, fast, precise, accurate, and sensitive and may be useful for routine analyses.     

Portable chemiluminescence multiplex biosensor for quantitative detection of three B19 DNA genotypes

A miniaturized multiplex biosensor exploiting a microfluidic oligonucleotide array and chemiluminescence (CL) lensless imaging detection has been developed for parvovirus B19 genotyping. The portable device consists of a reaction chip, comprising a glass slide arrayed with three B19 genotype-specific probes and coupled with a polydimethylsiloxane microfluidic layer, and a charge-coupled device camera modified for lensless CL imaging. Immobilized probes were used in DNA hybridization reactions with biotin-labeled targets, and then hybrids were measured by means of an avidin-horseradish peroxidase (HRP) conjugate and CL detection. All hybridization assay procedures have been optimized to be performed at room temperature through the microfluidic elements of the reaction chip, with sample and reagents delivery via capillary force exploiting adsorbent pads to drive fluids along the microchannels. The biosensor enabled multiplex detection of all B19 genotypes, with detectability down to 80 pmol?L^?1 for all B19 genotype oligonucleotides and 650 pmol?L^?1 for the amplified product of B19 genotype 1, which is comparable with that obtained in traditional PCR-ELISA formats and with notably shorter assay time (30 min vs. 2 h). The specificity of the assay has been evaluated by performing DNA–DNA hybridization reactions among sequences with different degrees of homology, and no cross hybridizations among B19 genotypes have been observed. The clinical applicability has been demonstrated by assaying amplified products obtained from B19 reference serum samples, with results completely consistent with the reference PCR-ELISA method. The next crucial step will be integration in the biosensor of a miniaturized PCR system for DNA amplification and for heat treatment of amplified products.

Synthesis of Optically Active 2- and 3-Sec-Butyl Half-Protected Succinaldehydes Through A Common Intermediate

Optically active (2RS,3S)-2-(ethanediyldioxyethyl)-3-methylpentanal (1) and (3RS,4S)-4-methyl-3-(N-methylthiazolidine-2-yl)-hexanal (2) were prepared from (3RS,4S)-4-methyl-3-(N-methyl-thiazolidine-2-yl)-1,1-ethanediyldioxyhexane.     

Solvent-Free Microwave-Assisted Organic Reactions Preparation of β-Keto Esters

Microwave technique has been utilised in the preparation of β-keto esters. Two different procedures are described: transesterification of β-keto esters and ring opening of 2,2,6-trimethyl-1,3-dioxin-4-one.     

Quantitative analysis of complex amino acids and RGD peptides by X‐ray photoelectron spectroscopy (XPS)

The C 1 s, N 1 s, and O 1 s core level binding energies (BEs) of the functional groups in amino acids (glycine, aspartic acid, glutamic acid, arginine, and histidine) with varied side‐chains and cell‐binding RGD‐based peptides have been determined and characterized by X‐ray photoelectron spectroscopy with a monochromatic Al K_α source. The zwitterionic nature of the amino acids in the solid state is unequivocally evident from the N 1 s signals of the protonated amine groups and the C 1 s signature of carboxylate groups. Significant adventitious carbon contamination is evident for all samples but can be quantitatively accounted for. No intrinsic differences in the XP spectra are evident between two polymorphs (α and γ) of glycine, indicating that the crystallographic differences have a minor influence on the core level BEs for this system. The two nitrogen centers in the imidazole group of histidine exhibit an N 1 s BE shift that is in line with previously reported data for theophylline and aqueous imidazole solutions, while the nitrogen and carbon chemical shifts reflect the unusual guanidinium chemical environment in arginine. It is shown that the complex envelopes of C 1 s and O 1 s photoemission spectra for short‐chain peptides can be analyzed quantitatively by reference to the less complex XP spectra of the constituent amino acids, provided the peptides are of high enough purity. The distinctive N 1 s photoemission from the amide linkages provides an indicator of peptide formation even in the presence of common impurities, and variations in the relative intensities of N 1 s were found to be diagnostic for each of the three peptides investigated (RGD, RGDS, and RGDSC). Copyright © 2013 John Wiley & Sons, Ltd.     

Design and Synthesis of a γ1β8‐Cyclodextrin Oligomer: A New Platform with Potential Application as a Dendrimeric Multicarrier

We report the synthesis and characterization of a water‐soluble, star‐shaped macromolecular platform consisting of eight β‐cyclodextrin (β‐CD) units anchored to the narrower rim of a γ‐CD core through bis(triazolyl)alkyl spacers. The efficient synthetic protocol is based on the microwave (MW)‐promoted Cu‐catalyzed 1,3‐dipolar cycloaddition of CD monoazides to CD monoacetylenes. The ligand‐hosting capability of the construct has been assessed by relaxometric titration and nuclear magnetic relaxation dispersion (NMRD) profiling, which showed it to be good, and this was supported by molecular dynamics simulations. To demonstrate the feasibility of obtaining supramolecular structures with high hosting ability, we designed a dimeric platform, formed by joining two nonamers through the γ‐CD cores through a bis(lithocholic acid) linker. With a view to the potential biological applications, cytotoxicity and extent of binding to human serum albumin were assessed. The properties of this dendrimeric multicarrier make it suitable for pharmaceutical and diagnostic purposes, ranging from targeted drug delivery to molecular imaging.