Search

This work documents the influence of the position of single carboxymethyl group on the β-cyclodextrin skeleton on the enantioselectivity. These synthesized monosubstituted carboxymethyl cyclodextrin (CD) derivatives, native β-cyclodextrin, and commercially available carboxymethyl-β-cyclodextrin with degree of substitution approximately 3 were used as additives into the BGE consisting of phosphate buffer at 20 mmol/L concentration, pH 2.5, and several biologically significant low-molecular-mass chiral compounds were enantioseparated by CE. The results indicate that different substituent location on β-cyclodextrin skeleton has a significant influence on the enantioseparation of the investigated enantiomers. The enantioselectivity of 2(I)-O-regioisomer was better than with native β-cyclodextrin. Comparable results to native β-cyclodextrin were obtained for 6(I)-O- regioisomer and the enantioselectivity of 3(I)-O-regioisomer was even worse than with native β-cyclodextrin. Commercially available derivative of CD provides better resolutions than the monosubstituted carboxymethyl CD derivatives for most of the investigated analytes., (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

In this work, open-tubular capillary electrochromatography (OT-CEC) method with bare gold nanoparticles (GNPs)-based stationary phase has been developed and applied for separation of tryptic peptide fragments of native and glycated proteins, bovine serum albumin (BSA), and human transferrin (HTF). The GNPs-based stationary phase was prepared by immobilization of bare GNPs, freshly reduced from tetrachloroaurate(III) ions by citrate reduction, on the sol-gel pretreated inner wall of the fused silica capillary. The separation efficiency, peak capacity, and peptide recovery of this open-tubular capillary column were investigated by varying the experimental parameters such as type and concentration of the buffering constituent and pH of the background electrolyte (BGE), temperature, and separation voltage. The best separations of the above tryptic peptides were achieved in the BGE composed of aqueous 100 mmol/L sodium phosphate buffer, pH 2.5, at separation voltage 10 kV per 47-cm long, 50 μm inside diameter capillary thermostated at 25°C. OT-CEC with bare GNPs stationary phase is shown to be a suitable technique for separation of complex peptide mixtures arising from tryptic digestion of native and glycated BSA and HTF, and for investigation of glycation (nonenzymatic glycosylation) of these proteins., (© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Surface of polyethyleneterephthalate (PET) was modified by plasma discharge and subsequently grafted with dithiols (1, 2-ethanedithiol (ED) or 4, 4'-biphenyldithiol) to create the thiol (-SH) groups on polymer surface. This "short" dithiols are expected to be fixed via one of -SH groups to radicals created by the plasma treatment on the PET surface. "Free" -SH groups are allowed to interact with Au nanoparticles. X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and electrokinetic analysis (EA, zeta potential) were used for the characterization of surface chemistry of the modified PET. Surface morphology and roughness of the modified PET were studied by atomic force microscopy (AFM). The results from XPS, FTIR, EA and AFM show that the Au nanoparticles are grafted on the modified surface only in the case of biphenyldithiol pretreatment. The possible explanation is that the "flexible" molecule of ethanedithiol is bounded to the activated PET surface with both -SH groups. On the contrary, the "rigid" molecule of biphenyldithiol is bounded via only one -SH group to the modified PET surface and the second one remains "free" for the consecutive chemical reaction with Au nanoparticle. The gold nanoparticles are distributed relatively homogenously over the polymer surface.

This study deals with preparation of substrates suitable for surface-enhanced Raman spectroscopy (SERS) applications by sputtering deposition of gold layer on the polytetrafluorethylene (PTFE) foil. Time of sputtering was investigated with respect to the surface properties. The ability of PTFE-Au substrates to enhance Raman signals was investigated by immobilization of biphenyl-4,4'-dithiol (BFD) from the solutions with various concentrations. BFD was also used for preparation of sandwich structures with Au or Ag nanoparticles by two different procedures. Results showed that PTFE can be used for fabrication of SERS active substrate with easy handle properties at low cost. This substrate was sufficient for the measurement of SERS spectrum of BFD even at 10-8 mol/l concentration.

Two porphyrin-brucine quaternary ammonium salts were immobilized on gold nanoparticles and their suitability for both in vitro and in vivo photodynamic therapy (PDT) was assayed using the basaloid squamous cell carcinoma PE/CA-PJ34 cell line. In vitro PDT experiments revealed that the gold nanoparticle-bound conjugates were less effective than unbound conjugates in killing cells. However, the same conjugates were more effective in reducing tumor size in vivo, with complete tumor regression observed.

Glycosides of benzodioxole-indole alkaloid 6-hydroxy-galanthindole (7-(6'-(hydroxymethyl)benzo[d][1',3']dioxol-5'-yl)-1-methyl-1H-indol-6-ol) having axial chirality were isolated from Narcissus cultivar 'Dutch Master'. The structure, including absolute configuration, was determined by means of extensive spectroscopic data such as UV, IR, CD, MS, 1D and 2D NMR spectra, and computational chiroptical methods. The aglycone has a structure containing two aromatic moieties with substituents hindering rotation about the biaryl axis and is connected to a saccharide moiety linked at C-6 and made up of one, two, or three sugars (glucose, alpha-L-rhamnopyranosyl-(1-->6)-beta-D-glucopyranose, and trisaccharide ([beta-D-xylopyranosyl(1-->2)]-[alpha-L-rhamnopyranosyl-(1-->6)]-beta-D-glucopyranose)., (2009 Elsevier Ltd. All rights reserved.)

The review article is devoted mainly to the description of applications of gold nanoparticles (GNPs) in separation sciences, especially in electromigration and chromatographic techniques. The applications of GNPs in particular separation methods, CE, microchip CE, MEKC, CEC, HPLC and GC, are classified according to the molecular size of the analytes from low-molecular-mass compounds via medium sized substances to biopolymers (proteins and nucleic acids). A very recent and promising utilization of GNPs for sample preparation, preconcentration and preseparation of selected analytes from complex matrices is presented as well. Moreover, in two introductory sections, typical preparation procedures of the GNPs and their modifications are presented and physico-chemical and analytical methods employed for characterization of the native and modified GNPs are briefly introduced.

Glycosides of arylnaphthalene lignans having axial chirality were isolated from Acanthus mollis. Owing to the axial chirality, their structure, including absolute configuration, was determined by means of extensive spectroscopic data such as UV, IR, MS, 1D and 2D NMR spectra, and computational chiroptical methods. A compound, 2',4-dihydroxyretrohelioxanthin (2'-hydroxy-justirumalin), has a structure containing two aromatic moieties with substituents hindering rotation about the biaryl axis. The aglycone was connected to a saccharide moiety linked at C-4 or C-2' and made up of one or four sugars (rhamnose or quinovose, and tetrasaccharide 4-O-beta-D-xylopyranosyl-(1'''''-6'')-O-[beta-D-rhamnopyranosyl-(1''''-3'')]-O-beta-D-apiofuranosyl-(1''''-2'')-O-beta-D-glucopyranoside and quinovose). Two mono- and one tetraglycoside gave positive results in the sea urchin eggs test (Paracentrotus lividus) of cytotoxicity and in a crown gall tumor on potato disks test (Agrobacterium tumefaciens).

A new xanthone derivative having axial chirality was isolated from Penicillium vinaceum. Owing to the axial chirality, its structure, including absolute configuration, was determined by means of extensive spectroscopic data, such as UV, IR, MS, and 1D and 2D NMR spectra, and computational chiroptical methods. The new compound, (a R)-2'-methoxyvinaxanthone, has a structure containing two aromatic moieties with substituents hindering rotation about the biaryl axis. The compound gave positive results in a sea urchin egg test ( Paracentrotus lividus) and a crown gall tumor on potato disks test (Agrobacterium tumefaciens).