No abstract

Based on a preactivation strategy using the (p-Tol)2SO/Tf2O system, a series of nucleosides were synthesized by coupling various thioglycosides with pyrimidines and purines under mild conditions. High yields and excellent β-stereoselectivities were obtained with either armed or disarmed N-glycosylation donors by tuning the amount of (p-Tol)2SO additive.

N,N-Di-2-picolylamine (DPA)-derived diboronic acid receptors (NHBAs) with a flexible linker were designed and synthesized in this study, and two-component sensing ensembles based on cationic NHBAs and an anionic fluorescent indicator 8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt (HPTS) were successfully developed for both monosaccharides and disaccharides sensing. The dibranched ortho-substituted receptor NHoBA exhibited unexpected selectivity towards lactose among five disaccharides used. The discrimination of five disaccharides and six monosaccharides was finally achieved by the integrated sensor array through linear discriminant analysis (LDA).

Recent investigations revealed the close relationship between H 2 S and HNO in biological systems. It is significant to develop an efficient fluorescent sensor to realize the discriminative sensing of HNO and H 2 S. Herein, we designed and synthesized a novel fluorescent sensor (CuHCD) with hemicyanine-carbazole as fluorophore and bipyridine-triazole-Cu 2+ complex as receptor, which enabled the selective recognition of HNO and H 2 S respectively via the non-covalent modulation of surfactant assemblies. The CuHCD/surfactant sensor system exhibited excellent selectivity for H 2 S at 5 mM SDS in HEPES buffer, and displayed high specificity for HNO at 1 mM SDS in HEPES buffer over other common anions and reactive species. Different detection mechanisms in sensing H 2 S and HNO were deeply investigated. The results showed that H 2 S seized Cu 2+ from the complex to recover the fluorescence of HCD, while HNO reduced Cu 2+ to Cu + in the complex to turn on the fluorescence. In different SDS micellar systems, HCD possessed different dispersity and binding capacity with Cu 2+ , which led to the selective detection of H 2 S and HNO, respectively. The hypothesis was further confirmed by replacing SDS micelles with liposome under the same conditions.

Four-channel fluorescence assay toward six monosaccharides was achieved by employing two novel pyrene-functionalized boronlectins with flexible diboronic acid as receptors. The effects of pH values and aging time on the sensor properties were thoroughly evaluated by UV-vis, fluorescence spectroscopy and dynamic light scattering. We find that the fluorescence relative ratios were highly correlated with analyte concentrations at μM level. The flexibility of the receptors was perceived as an indispensable factor to produce diverse fluorescence signals toward different monosaccharides. Most importantly, integration of four fluorescence channels derived from the two sensors enables an excellent discrimination for all tested monosaccharides at a certain concentration or a concentration range via linear discriminant analysis (LDA). It is proposed that the multiple flexible linkers in the boronlectins could increase their self-adaptive capacity for different analytes, and facilitate the formation of stable boronlectin-sugar aggregate assemblies. In addition, practical sensing of glucose in the simulative blood and urine was illustrated to be feasible in the presence of interferences at physiological concentrations.