Abstractseries of novel highly water-soluble neutral BODIPY dyes have been obtained by functionalization of BODIPY dyes with branched oligo(ethylene glycol) methyl ether groups at positions 8, 2 and 6 or 4 and 4′. Use of an ortho-substituent group of branched oligo(ethylene glycol)methyl ether on the meso-phenyl ring of BODIPY dyes, and replacement of the fluorine atoms of BODIPY dyes at positions 4 and 4′ with methyloxy or ethynyl subunits significantly enhances fluorescence quantum yields of BODIPY dyes.BODIPY (4,4′-difluoro-4-bora-3a,4a-diaza-s-indacene) dyes have gained a great deal of attention recently because of their many distinctive and desirable properties such as high extinction coefficients, narrow absorption and emission bands, high quantum efficiencies of fluorescence, and relative insensitivity to environmental perturbations, and resistance to photobleaching. 1 Biological and medical applications of the BODIPY dyes require good water solubility and resistance to the formation of nonfluorescent dimer and higher aggregates. Reported strategies to make these dyes water soluble typically involve introduction of oligo(ethylene glycol), N,N-bis(2-hydroxyethyl) amine, carbohydrates, nucleotides, or ionic hydrophilic groups such as carboxylic acid, sulfonic acid, or ammonium groups to BODIPY dyes. 2 However, neutral water soluble BODIPY dyes have advantages over ionic ones because they avoid potential nonspecific interactions through electrostatic interactions between BODIPY dyes and proteins or other biomolecules in We hypothesize that incorporation of branched oligo(ethylene glycol)methyl ether into BODIPY dyes could effectively enhance enthalpic interactions of BODIPY dyes with water and significantly increase water solubility of BODIPY dyes, and that introduction of steric hindrance at the meso or 4-position of BODIPY dyes could significantly reduce their aggregation through π-π stacking interactions between BOIDIPY cores in aqueous solution, and considerably enhance their fluorescence quantum yields. In this letter, we have introduced branched oligo(ethylene glycol)methyl ether to the meso, 2-and 6-, and 4-positions of BODIPY dyes and demonstrated significantly enhanced fluorescence quantum yields of the new dyes (the abstract scheme). These neutral BODIPY dyes are highly water soluble because of the strong hydrophilic nature of oligo(ethylene glycol)methyl ether residues. These approaches offer very efficient ways to prepare different BODIPY dyes with emission ranging from green to deep red regions.In order to demonstrate the feasibility of using branched oligo(ethylene glycol)methyl ether to enhance the water solubility of BODIPY dyes, we first introduced branched oligo(ethylene glycol)methyl ether to BODIPY dyes at the meso position (Scheme 1).Compound 4 was prepared according to a reported procedure 3 and further brominated with PBr 3 in methylene chloride at 40 °C, affording brominated branched oligo(ethylene glycol)methyl ether (5). The benzaldehyde deriviative bearing branched oligo(ethylene g...

In this report, a new polythiophene interface is fabricated containing fused quinone moieties which are then glycosylated to form a carbohydrate platform for bacterial detection. Very importantly, this interface can be used for label-free and reagentless detection, both by electrochemical and Quartz Crystal Microbalance (QCM) transducers and by using the direct pili-mannose binding as well as Concanavalin A (Con A) mediated lipopolysaccharides (LPS)-mannose binding. The conductive polymer's unique collective properties are very sensitive to very minor perturbations, which result in significant changes of electrical conductivity and providing amplified sensitivity and improved limits of detection (i.e., 25 cell/mL for electrochemical sensor and 50 cells/mL for QCM sensor), a widened logarithmic range of detection (i.e., 3-7 for pili-mannose binding and 2-8 for Con A mediated binding), high specificity and selectivity, and an extraordinary reliability by a mechanism of internal validation. With these analytical performances, the described biosensor is envisaged for being capable of differentiating Gram-negative bacterial strain and species, for many important applications.

Core fucosylation of N-glycoproteins plays a crucial role in modulating the biological functions of glycoproteins. Yet, the synthesis of structurally well-defined, core-fucosylated glycoproteins remains a challenging task due to the complexity in multi-step chemical synthesis or the inability of the biosynthetic α1,6-fucosyltransferase (FUT8) to directly fucosylate full-size mature N-glycans in a chemoenzymatic approach. We report in this paper the design and generation of potential α1,6-fucosynthase and fucoligase for direct core-fucosylation of intact N-glycoproteins. We found that mutation at the nucleophilic residue (D200) did not provide a typical glycosynthase from this bacterial enzyme, but several mutants with mutation at the general acid/base residue E274 of the Lactobacillus casei α1,6-fucosidase, including E274A, E274S, and E274G, acted as efficient glycoligases that could fucosylate a wide variety of complex N-glycopeptides and intact glycoproteins by using α-fucosyl fluoride as a simple donor substrate. Studies on the substrate specificity revealed that the α1,6-fucosidase mutants could introduce an α1,6-fucose moiety specifically at the Asn-linked GlcNAc moiety not only to GlcNAc-peptide, but also to high-mannose and complex type N-glycans in the context of N-glycopeptides, N-glycoproteins, and intact antibodies. This discovery opens a new avenue to a wide variety of homogeneous, core-fucosylated N-glycopeptides and N-glycoproteins that are hitherto difficult to obtain for structural and functional studies.

No abstract

Mapping surface hydrophobic interactions in proteins is key to understanding molecular recognition, biological functions, and is central to many protein misfolding diseases. Herein, we report synthesis and application of new BODIPY-based hydrophobic sensors (HPsensors) that are stable and highly fluorescent for pH values ranging from 7.0 to 9.0. Surface hydrophobic measurements of proteins (BSA, apomyoglobin, and myoglobin) by these HPsensors display much stronger signal compared to 8-anilino-1-naphthalene sulfonic acid (ANS), a commonly used hydrophobic probe; HPsensors show a 10- to 60-fold increase in signal strength for the BSA protein with affinity in the nanomolar range. This suggests that these HPsensors can be used as a sensitive indicator of protein surface hydrophobicity. A first principle approach is used to identify the molecular level mechanism for the substantial increase in the fluorescence signal strength. Our results show that conformational change and increased molecular rigidity of the dye due to its hydrophobic interaction with protein lead to fluorescence enhancement.

A highly water-soluble BODIPY dye bearing electron-rich o-diaminophenyl groups at 2,6-positions was prepared as a highly sensitive and selective fluorescent probe for detection of nitric oxide (NO) in living cells. The fluorescent probe displays an extremely weak fluorescence with fluorescence quantum yield of 0.001 in 10 mM phosphate buffer (pH 7.0) in the absence of NO as two electron-rich o-diaminophenyl groups at 2,6-positions significantly quench the fluorescence of the BODIPY dye via photoinduced electron transfer mechanism. The presence of NO in cells enhances the dye fluorescence dramatically. The fluorescent probe demonstrates excellent water solubility, membrane permeability, and compatibility with living cells for sensitive detection of NO.

No abstract

Formyl groups at 6-and 2,6-positions initiated Knoevenagel reactions of the methyl groups at the 7, and 1,7-positions of 1,3,5,7-tetramethyl BODIPY dyes with aromatic aldehydes. Formation of vinyl bonds at the 7-, and 1,7-positions facilitates further Knoevenagel reactions of the methyl groups at the 3,5positions. This approach offers fast, facile and versatile ways to prepare potential novel building blocks of BODIPY dyes for conjugated oligomers, dendrimers, and highly water-soluble, near-infrared emissive sensing materials.