Design,characterization and applications of new ionic liquid matrices for multifunctional analysis of biomolecules: A novel strategy for pathogenic bacteria biosensing

The design, preparation and performance for novel UV-light absorbing (room-temperature) ionic liquid matrices (UV-RTILMs) for matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS) were reported. A series of UV-RTILMs was prepared by ultrasonication of equimolar of acid (mefenamic acid) and bases (aniline (ANI), pyridine (Pyr), dimethyl aniline (DMANI) and 2-methyl picoline (2-P)). The UV-RTILMs have not only significant absorbance at the desired wavelength (337 nm of the N₂ Laser), but also have available protons that can easily undergo proton transfer reactions to ionize the target molecules. The novel UV-RTILMs have the ability to ionize different and wide classes of compounds such as drugs, carbohydrate, and amino acids. The new UV-RTILMs series have been successfully and selectively applied for biosensing the lysates of pathogenic bacteria in the presence of the cell macromolecules. A new strategy for biosensing pathogens was presented via sensing the pathogens lysate in the cell suspension. The new materials can effectively detect the bacterial toxins without separation or any pretreatment. They offered excellent ionization of labile oligosaccharides with protonated peaks. They could significantly enhance the analyte signals, produce homogeneous spotting, reducing spot-to-spot variation, excellent vacuum stability, higher ion peak intensity, and wide application possibility. The physical parameters such as molar refractivity, molar volume, parachor, surface tension, density and polarizability were calculated and tabulated. The new UV-RTILMs could offer excellent reproducibility and great repeatability and they are promising matrices for wide applications on MALDI-MS.     

On-line gradient liquid chromatography-Fourier transform infrared spectrometry determination of sugars in beverages using chemometric background correction

An on-line gradient reversed phase liquid chromatography-Fourier transform infrared spectrometry (LC-FTIR) method was developed for the determination of fructose, glucose, sucrose and maltose in beverages. Improved chromatographic resolution was obtained using a linear gradient from 75 to 55% (v/v) acetonitrile in water in 15 min. Changes in the background spectra were corrected employing “univariate background correction based on the use of a reference spectra matrix” (UBC-RSM) and using the ratio of absorbance (AR) at 2256 and 2253 cm⁻¹ for the identification of the eluent spectra within the RSM. The method provided limits of detection in the order of 0.75 mg ml⁻¹. The precision (as relative standard deviation) ranged between 3.3 and 4.1% for glucose and fructose, respectively at a concentration level of 3.0 mg ml⁻¹. Quantitative recovery values on spiked samples confirmed the accuracy of the method. A set of samples from the Spanish market were analysed to test the suitability of the procedure.     

Novel synthesis of oligosaccharides linked with carbamate and urea bonds utilizing modified Curtius rearrangement

We describe a novel synthesis of various carbamate- and urea-linked disaccharides stereospecifically using sugar carboxylic acids and sugar alcohols or sugar amines by the modified Curtius rearrangement. In this reaction, the reactivity of each hydroxyl group in glucose as an acceptor has been disclosed. Furthermore, we applied this method to the synthesis of carbamate-linked oligosaccharides including a dendritic molecule.     

Novel class of non-ionic monocatenary and bolaform alkylglycoside surfactants. Synthesis by microwave-assisted glycosylation and olefin cross-metathesis or by ‘click-chemistry’: physicochemical studies

We develop herein the synthesis of a new class of monocatenary and bolaform surfactants from d-glucose, d-galactose and lactose. Two main pathways have been investigated: microwave-assisted glycosylation followed by olefin cross-metathesis, and the one-step click-chemistry methodology. Tensioactive properties of these new compounds have been studied in order to characterize the physicochemical behaviour of these new carbohydrate-based compounds in water.     

Synthesis of N-modified sTn analogs and evaluation of their immunogenicities by microarray-based immunoassay

A series of sTn derivative-keyhole limpet hemocyanin (KLH) conjugates were synthesized, and their immunogenicities were evaluated by corresponding IgG production. To achieve a high-throughput screening immunoassay, a glycan microarray with sTn and its analogs was used to detect the production of corresponding antibodies in mouse sera. The immunoassay results revealed that the derived sTn antigens are generally more immunogenic than the parent sTn antigen. The N-propionyl sTn antigen was the most immunogenic among the sTn derivatives investigated, and its antiserum was cross-reactive with natural sTn. These results indicate that N-propionyl sTn may serve as a viable vaccine candidate to produce antibody for detection of sTn antigen.     

脂肪酸糖酯类表面活性剂的合成及应用

脂肪酸糖酯是一类绿色、安全、可生物降解的非离子型表面活性剂,因其具有良好的乳化能力和杀菌性能以及对皮肤刺激性低等诸多优点而被广泛应用于食品、医药、化妆品和农业领域。本文对脂肪酸糖酯的合成及应用进行了综述,从而为深入研究并开发脂肪酸糖酯类表面活性剂提供参考。     

Chemical Synthesis of an Octasaccharide Derivative Related to Group B Streptococcus Cell-Wall Polysaccharide

Group B Streptococcus (GBS) is the major pathogen that causes invasive infectious diseases in neonates and infants. The development of preventive and therapeutic strategies against GBS infection has been becoming the most pressing subject worldwide. Group B carbohydrate (GBC), the group B-specific polysaccharide that distinguishes GBS with other streptococci species, has been identified as an attractive antigen for diagnosis and vaccine development because of its highly conservative tetra-antennary structure. In this paper, a highly convergent [3 + 5] glycosylation strategy for efficient synthesis of an octasaccharide derivative related to GBC oligosaccharide unit II has been developed. In this synthesis, each glycosylation reaction was efficiently constructed with glycosyl imidates, especially trifluoroacetimidate, as donors, and each glycosidic bond was stereoselectively controlled via the neighboring group participation effect of acyl group on the 2-O-position of imidate donors or the solvent effect of Et₂O. Furthermore, the aminoethylphosphate group was smoothly installed on the 6-O-position of d -glucitol residue using the phosphoramidite method. After global deprotection, the target octasaccharide was successfully obtained from d -glucitol in 29 steps with an overall yield of 1.37%. The free amino group installed on the aminoethylphosphate spacer of the target molecule enables its modification with functionalized biomolecules for further biological studies.